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1. First Very Long Baseline Interferometry Detections at 870{\mu}m

Author

Raymond, Alexander W., Doeleman, Sheperd S., Asada, Keiichi, Blackburn, Lindy, Bower, Geoffrey C., Bremer, Michael, Broguiere, Dominique, Chen, Ming-Tang, Crew, Geoffrey B., Dornbusch, Sven, Fish, Vincent L., García, Roberto, Gentaz, Olivier, Goddi, Ciriaco, Han, Chih-Chiang, Hecht, Michael H., Huang, Yau-De, Janssen, Michael, Keating, Garrett K., Koay, Jun Yi, Krichbaum, Thomas P., Lo, Wen-Ping, Matsushita, Satoki, Matthews, Lynn D., Moran, James M., Norton, Timothy J., Patel, Nimesh, Pesce, Dominic W., Ramakrishnan, Venkatessh, Rottmann, Helge, Roy, Alan L., Sánchez, Salvador, Tilanus, Remo P. J., Titus, Michael, Torne, Pablo, Wagner, Jan, Weintroub, Jonathan, Wielgus, Maciek, Young, André, Akiyama, Kazunori, Albentosa-Ruíz, Ezequiel, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Azulay, Rebecca, Bach, Uwe, Baczko, Anne-Kathrin, Ball, David, Baloković, Mislav, Bandyopadhyay, Bidisha, Barrett, John, Bauböck, Michi, Benson, Bradford A., Bintley, Dan, Blundell, Raymond, Bouman, Katherine L., Boyce, Hope, Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Bronzwaer, Thomas, Bustamante, Sandra, Carlstrom, John E., Chael, Andrew, Chan, Chi-kwan, Chang, Dominic O., Chatterjee, Koushik, Chatterjee, Shami, Chen, Yongjun, Cheng, Xiaopeng, Cho, Ilje, Christian, Pierre, Conroy, Nicholas S., Conway, John E., Crawford, Thomas M., Cruz-Osorio, Alejandro, Cui, Yuzhu, Dahale, Rohan, Davelaar, Jordy, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Dexter, Jason, Dhruv, Vedant, Dihingia, Indu K., Dzib, Sergio A., Eatough, Ralph P., Emami, Razieh, Falcke, Heino, Farah, Joseph, Fomalont, Edward, Fontana, Anne-Laure, Ford, H. Alyson, Foschi, Marianna, Fraga-Encinas, Raquel, Freeman, William T., Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, Gammie, Charles F., Georgiev, Boris, Gold, Roman, Gómez-Ruiz, Arturo I., Gómez, José L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Hesper, Ronald, Heumann, Dirk, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Impellizzeri, C. M. Violette, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Jeter, Britton, Jiang, Wu, Jiménez-Rosales, Alejandra, Johnson, Michael D., Jorstad, Svetlana, Jones, Adam C., Joshi, Abhishek V., Jung, Taehyun, Karuppusamy, Ramesh, Kawashima, Tomohisa, Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Kocherlakota, Prashant, Kofuji, Yutaro, Koch, Patrick M., Koyama, Shoko, Kramer, Carsten, Kramer, Joana A., Kramer, Michael, Kubo, Derek, Kuo, Cheng-Yu, La Bella, Noemi, Lee, Sang-Sung, Levis, Aviad, Li, Zhiyuan, Lico, Rocco, Lindahl, Greg, Lindqvist, Michael, Lisakov, Mikhail, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin J., Lowitz, Amy E., Lu, Ru-Sen, MacDonald, Nicholas R., Mahieu, Sylvain, Maier, Doris, Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Martí-Vidal, Iván, Medeiros, Lia, Menten, Karl M., Mizuno, Izumi, Mizuno, Yosuke, Montgomery, Joshua, Moriyama, Kotaro, Moscibrodzka, Monika, Mulaudzi, Wanga, Müller, Cornelia, Müller, Hendrik, Mus, Alejandro, Musoke, Gibwa, Myserlis, Ioannis, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Fuentes, Santiago Navarro, Neilsen, Joey, Ni, Chunchong, Nowak, Michael A., Oh, Junghwan, Okino, Hiroki, Sánchez, Héctor Raúl Olivares, Oyama, Tomoaki, Özel, Feryal, Palumbo, Daniel C. M., Paraschos, Georgios Filippos, Park, Jongho, Parsons, Harriet, Pen, Ue-Li, Piétu, Vincent, PopStefanija, Aleksandar, Porth, Oliver, Prather, Ben, Principe, Giacomo, Psaltis, Dimitrios, Pu, Hung-Yi, Raffin, Philippe A., Rao, Ramprasad, Rawlings, Mark G., Ricarte, Angelo, Ripperda, Bart, Roelofs, Freek, Romero-Cañizales, Cristina, Ros, Eduardo, Roshanineshat, Arash, Ruiz, Ignacio, Ruszczyk, Chet, Rygl, Kazi L. J., Sánchez-Argüelles, David, Sánchez-Portal, Miguel, Sasada, Mahito, Satapathy, Kaushik, Savolainen, Tuomas, Schloerb, F. Peter, Schonfeld, Jonathan, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Salas, León David Sosapanta, Souccar, Kamal, Srinivasan, Ranjani, Stanway, Joshua S., Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Toma, Kenji, Toscano, Teresa, Traianou, Efthalia, Trent, Tyler, Trippe, Sascha, Turk, Matthew, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Vos, Jesse, Ward-Thompson, Derek, Wardle, John, Washington, Jasmin E., Wharton, Robert, Wiik, Kaj, Witzel, Gunther, Wondrak, Michael F., Wong, George N., Wu, Qingwen, Yadlapalli, Nitika, Yamaguchi, Paul, Yfantis, Aristomenis, Yoon, Doosoo, Younsi, Ziri, Yu, Wei, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhang, Shuo, Zhao, Guang-Yao, and Zhao, Shan-Shan

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

The first very long baseline interferometry (VLBI) detections at 870$\mu$m wavelength (345$\,$GHz frequency) are reported, achieving the highest diffraction-limited angular resolution yet obtained from the surface of the Earth, and the highest-frequency example of the VLBI technique to date. These include strong detections for multiple sources observed on inter-continental baselines between telescopes in Chile, Hawaii, and Spain, obtained during observations in October 2018. The longest-baseline detections approach 11$\,$G$\lambda$ corresponding to an angular resolution, or fringe spacing, of 19$\mu$as. The Allan deviation of the visibility phase at 870$\mu$m is comparable to that at 1.3$\,$mm on the relevant integration time scales between 2 and 100$\,$s. The detections confirm that the sensitivity and signal chain stability of stations in the Event Horizon Telescope (EHT) array are suitable for VLBI observations at 870$\mu$m. Operation at this short wavelength, combined with anticipated enhancements of the EHT, will lead to a unique high angular resolution instrument for black hole studies, capable of resolving the event horizons of supermassive black holes in both space and time., Comment: Corresponding author: S. Doeleman

Published
2024
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2. A search for pulsars around Sgr A* in the first Event Horizon Telescope dataset

Author

Torne, Pablo, Liu, Kuo, Eatough, Ralph P., Wongphechauxsorn, Jompoj, Cordes, James M., Desvignes, Gregory, De Laurentis, Mariafelicia, Kramer, Michael, Ransom, Scott M., Chatterjee, Shami, Wharton, Robert, Karuppusamy, Ramesh, Blackburn, Lindy, Janssen, Michael, Chan, Chi-kwan, Crew, Geoffrey B., Matthews, Lynn D., Goddi, Ciriaco, Rottmann, Helge, Wagner, Jan, Sanchez, Salvador, Ruiz, Ignacio, Abbate, Federico, Bower, Geoffrey C., Salamanca, Juan J., Gomez-Ruiz, Arturo I., Herrera-Aguilar, Alfredo, Jiang, Wu, Lu, Ru-Sen, Pen, Ue-Li, Raymond, Alexander W., Shao, Lijing, Shen, Zhiqiang, Paubert, Gabriel, Sanchez-Portal, Miguel, Kramer, Carsten, Castillo, Manuel, Navarro, Santiago, John, David, Schuster, Karl-Friedrich, Johnson, Michael D., Rygl, Kazi L. J., Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Bach, Uwe, Baczko, Anne-Kathrin, Ball, David, Balokovic, Mislav, Barrett, John, Bauboeck, Michi, Benson, Bradford A., Bintley, Dan, Blundell, Raymond, Bouman, Katherine L., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Broguiere, Dominique, Bronzwaer, Thomas, Bustamante, Sandra, Byun, Do-Young, Carlstrom, John E., Ceccobello, Chiara, Chael, Andrew, Chang, Dominic O., Chatterjee, Koushik, Chen, Ming-Tang, Chen, Yongjun, Cheng, Xiaopeng, Cho, Ilje, Christian, Pierre, Conroy, Nicholas S., Conway, John E., Crawford, Thomas M., Cruz-Osorio, Alejandro, Cui, Yuzhu, Dahale, Rohan, Davelaar, Jordy, Deane, Roger, Dempsey, Jessica, Dexter, Jason, Dhruv, Vedant, Doeleman, Sheperd S., Dougal, Sean, Dzib, Sergio A., Emami, Razieh, Falcke, Heino, Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Ford, H. Alyson, Foschi, Marianna, Fraga-Encinas, Raquel, Freeman, William T., Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, Gammie, Charles F., Garcia, Roberto, Gentaz, Olivier, Georgiev, Boris, Gold, Roman, Gomez, Jose L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Haworth, Kari, Hecht, Michael H., Hesper, Ronald, Heumann, Dirk, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Impellizzeri, C. M. Violette, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Jeter, Britton, Jimenez-Rosales, Alejandra, Jorstad, Svetlana, Joshi, Abhishek V., Jung, Taehyun, Karami, Mansour, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kocherlakota, Prashant, Kofuji, Yutaro, Koyama, Shoko, Krichbaum, Thomas P., Kuo, Cheng-Yu, La Bella, Noemi, Lauer, Tod R., Lee, Daeyoung, Lee, Sang-Sung, Leung, Po Kin, Levis, Aviad, Li, Zhiyuan, Lico, Rocco, Lindahl, Greg, Lindqvist, Michael, Lisakov, Mikhail, Liu, Jun, Liuzzo, Elisabetta, Lo, Wen-Ping, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin J., MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Marti-Vidal, Ivan, Matsushita, Satoki, Medeiros, Lia, Menten, Karl M., Michalik, Daniel, Mizuno, Izumi, Mizuno, Yosuke, Moran, James M., Moriyama, Kotaro, Moscibrodzka, Monika, Muller, Cornelia, Muller, Hendrik, Mus, Alejandro, Musoke, Gibwa, Myserlis, Ioannis, Nadolski, Andrew, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayan, Ramesh, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Neilsen, Joey, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Oh, Junghwan, Okino, Hiroki, Olivares, Hector, Ortiz-Leon, Gisela N., Oyama, Tomoaki, Ozel, Feryal, Palumbo, Daniel C. M., Paraschos, Georgios Filippos, Park, Jongho, Parsons, Harriet, Patel, Nimesh, Pesce, Dominic W., Pietu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Potzl, Felix M., Prather, Ben, Preciado-Lopez, Jorge A., Psaltis, Dimitrios, Pu, Hung-Yi, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Rezzolla, Luciano, Ricarte, Angelo, Ripperda, Bart, Roelofs, Freek, Rogers, Alan, Ros, Eduardo, Romero-Cañizales, Cristina, Roshanineshat, Arash, Roy, Alan L., Ruszczyk, Chet, Sanchez-Arguelles, David, Sasada, Mahito, Satapathy, Kaushik, Savolainen, Tuomas, Schloerb, F. Peter, Schonfeld, Jonathan, Small, Des, Sohn, Bong Won, SooHoo, Jason, Souccar, Kamal, Sun, He, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Toscano, Teresa, Traianou, Efthalia, Trent, Tyler, Trippe, Sascha, Turk, Matthew, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Vos, Jesse, Ward-Thompson, Derek, Wardle, John, Weintroub, Jonathan, Wex, Norbert, Wielgus, Maciek, Wiik, Kaj, Witzel, Gunther, Wondrak, Michael F., Wong, George N., Wu, Qingwen, Yadlapalli, Nitika, Yamaguchi, Paul, Yfantis, Aristomenis, Yoon, Doosoo, Young, Andre, Young, Ken, Younsi, Ziri, Yu, Wei, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhang, Shuo, Zhao, Guang-Yao, and Zhao, Shan-Shan

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The Event Horizon Telescope (EHT) observed in 2017 the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), at a frequency of 228.1 GHz ($\lambda$=1.3 mm). The fundamental physics tests that even a single pulsar orbiting Sgr A* would enable motivate searching for pulsars in EHT datasets. The high observing frequency means that pulsars - which typically exhibit steep emission spectra - are expected to be very faint. However, it also negates pulse scattering, an effect that could hinder pulsar detections in the Galactic Center. Additionally, magnetars or a secondary inverse Compton emission could be stronger at millimeter wavelengths than at lower frequencies. We present a search for pulsars close to Sgr A* using the data from the three most-sensitive stations in the EHT 2017 campaign: the Atacama Large Millimeter/submillimeter Array, the Large Millimeter Telescope and the IRAM 30 m Telescope. We apply three detection methods based on Fourier-domain analysis, the Fast-Folding-Algorithm and single pulse search targeting both pulsars and burst-like transient emission; using the simultaneity of the observations to confirm potential candidates. No new pulsars or significant bursts were found. Being the first pulsar search ever carried out at such high radio frequencies, we detail our analysis methods and give a detailed estimation of the sensitivity of the search. We conclude that the EHT 2017 observations are only sensitive to a small fraction ($\lesssim$2.2%) of the pulsars that may exist close to Sgr A*, motivating further searches for fainter pulsars in the region., Comment: 33 pages, 7 figures, 6 Tables. Accepted for publication in ApJ

Published
2023

3. Reference Array and Design Consideration for the next-generation Event Horizon Telescope

Author

Doeleman, Sheperd S., Barrett, John, Blackburn, Lindy, Bouman, Katherine, Broderick, Avery E., Chaves, Ryan, Fish, Vincent L., Fitzpatrick, Garret, Fuentes, Antonio, Freeman, Mark, Gómez, José L., Haworth, Kari, Houston, Janice, Issaoun, Sara, Johnson, Michael D., Kettenis, Mark, Loinard, Laurent, Nagar, Neil, Narayanan, Gopal, Oppenheimer, Aaron, Palumbo, Daniel C. M., Patel, Nimesh, Pesce, Dominic W., Raymond, Alexander W., Roelofs, Freek, Srinivasan, Ranjani, Tiede, Paul, Weintroub, Jonathan, and Wielgus, Maciek

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We describe the process to design, architect, and implement a transformative enhancement of the Event Horizon Telescope (ngEHT). This program - the next-generation Event Horizon Telescope (ngEHT) - will form a networked global array of radio dishes capable of making high-fidelity real-time movies of supermassive black holes (SMBH) and their emanating jets. This builds upon the EHT principally by deploying additional modest-diameter dishes to optimized geographic locations to enhance the current global mm/submm wavelength Very Long Baseline Interferometric (VLBI) array, which has, to date, utilized mostly pre-existing radio telescopes. The ngEHT program further focuses on observing at three frequencies simultaneously for increased sensitivity and Fourier spatial frequency coverage. Here, the concept, science goals, design considerations, station siting and instrument prototyping are discussed, and a preliminary reference array to be implemented in phases is described., Comment: Submitted to the journal Galaxies

Published
2023
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4. Comparison of Polarized Radiative Transfer Codes used by the EHT Collaboration

Author

Prather, Ben S., Dexter, Jason, Moscibrodzka, Monika, Pu, Hung-Yi, Bronzwaer, Thomas, Davelaar, Jordy, Younsi, Ziri, Gammie, Charles F., Gold, Roman, Wong, George N., Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Bach, Uwe, Baczko, Anne-Kathrin, Ball, David, Baloković, Mislav, Barrett, John, Bauböck, Michi, Benson, Bradford A., Bintley, Dan, Blackburn, Lindy, Blundell, Raymond, Bouman, Katherine L., Bower, Geoffrey C., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Broguiere, Dominique, Bustamante, Sandra, Byun, Do-Young, Carlstrom, John E., Ceccobello, Chiara, Chael, Andrew, Chan, Chi-kwan, Chang, Dominic O., Chatterjee, Koushik, Chatterjee, Shami, Chen, Ming-Tang, Chen, Yongjun, Cheng, Xiaopeng, Cho, Ilje, Christian, Pierre, Conroy, Nicholas S., Conway, John E., Cordes, James M., Crawford, Thomas M., Crew, Geoffrey B., Cruz-Osorio, Alejandro, Cui, Yuzhu, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Dhruv, Vedant, Doeleman, Sheperd S., Dougal, Sean, Dzib, Sergio A., Eatough, Ralph P., Emami, Razieh, Falcke, Heino, Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Ford, H. Alyson, Fraga-Encinas, Raquel, Freeman, William T., Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, García, Roberto, Gentaz, Olivier, Georgiev, Boris, Goddi, Ciriaco, Gómez-Ruiz, Arturo I., Gómez, José L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Haworth, Kari, Hecht, Michael H., Hesper, Ronald, Heumann, Dirk, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Impellizzeri, C. M. Violette, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Janssen, Michael, Jeter, Britton, Jiang, Wu, Jiménez-Rosales, Alejandra, Johnson, Michael D., Jorstad, Svetlana, Joshi, Abhishek V., Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kocherlakota, Prashant, Kofuji, Yutaro, Koyama, Shoko, Kramer, Carsten, Kramer, Michael, Krichbaum, Thomas P., Kuo, Cheng-Yu, La Bella, Noemi, Lauer, Tod R., Lee, Daeyoung, Lee, Sang-Sung, Leung, Po Kin, Levis, Aviad, Li, Zhiyuan, Lico, Rocco, Lindahl, Greg, Lindqvist, Michael, Lisakov, Mikhail, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lo, Wen-Ping, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin J., Lu, Ru-Sen, MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Martí-Vidal, Iván, Matsushita, Satoki, Matthews, Lynn D., Medeiros, Lia, Menten, Karl M., Michalik, Daniel, Mizuno, Izumi, Mizuno, Yosuke, Moran, James M., Moriyama, Kotaro, Müller, Cornelia, Mus, Alejandro, Musoke, Gibwa, Myserlis, Ioannis, Nadolski, Andrew, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayan, Ramesh, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Fuentes, Santiago Navarro, Neilsen, Joey, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Oh, Junghwan, Okino, Hiroki, Olivares, Héctor, Ortiz-León, Gisela N., Oyama, Tomoaki, Özel, Feryal, Palumbo, Daniel C. M., Paraschos, Georgios Filippos, Park, Jongho, Parsons, Harriet, Patel, Nimesh, Pen, Ue-Li, Pesce, Dominic W., Piétu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Pötzl, Felix M., Preciado-López, Jorge A., Psaltis, Dimitrios, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Raymond, Alexander W., Rezzolla, Luciano, Ricarte, Angelo, Ripperda, Bart, Roelofs, Freek, Rogers, Alan, Ros, Eduardo, Romero-Cañizales, Cristina, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruiz, Ignacio, Ruszczyk, Chet, Rygl, Kazi L. J., Sánchez, Salvador, Sánchez-Argüelles, David, Sánchez-Portal, Miguel, Sasada, Mahito, Satapathy, Kaushik, Savolainen, Tuomas, Schloerb, F. Peter, Schonfeld, Jonathan, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Souccar, Kamal, Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Torne, Pablo, Traianou, Efthalia, Trent, Tyler, Trippe, Sascha, Turk, Matthew, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Vos, Jesse, Wagner, Jan, Ward-Thompson, Derek, Wardle, John, Weintroub, Jonathan, Wex, Norbert, Wharton, Robert, Wielgus, Maciek, Wiik, Kaj, Witzel, Gunther, Wondrak, Michael F., Wu, Qingwen, Yamaguchi, Paul, Yfantis, Aristomenis, Yoon, Doosoo, Young, André, Young, Ken, Yu, Wei, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhang, Shuo, Zhao, Guang-Yao, and Zhao, Shan-Shan

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrument for a particular model of the black hole accretion system. Such predictions are generated by general relativistic radiative transfer (GRRT) codes, which integrate the equations of polarized radiative transfer in curved spacetime. A selection of ray-tracing GRRT codes used within the EHT collaboration is evaluated for accuracy and consistency in producing a selection of test images, demonstrating that the various methods and implementations of radiative transfer calculations are highly consistent. When imaging an analytic accretion model, we find that all codes produce images similar within a pixel-wise normalized mean squared error (NMSE) of 0.012 in the worst case. When imaging a snapshot from a cell-based magnetohydrodynamic simulation, we find all test images to be similar within NMSEs of 0.02, 0.04, 0.04, and 0.12 in Stokes I, Q, U , and V respectively. We additionally find the values of several image metrics relevant to published EHT results to be in agreement to much better precision than measurement uncertainties., Comment: Accepted for publication in ApJ

Published
2023
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5. Enabling Transformational ngEHT Science via the Inclusion of 86 GHz Capabilities

Author

Issaoun, Sara, Pesce, Dominic W., Roelofs, Freek, Chael, Andrew, Dodson, Richard, Rioja, María J., Akiyama, Kazunori, Aran, Romy, Blackburn, Lindy, Doeleman, Sheperd S., Fish, Vincent L., Fitzpatrick, Garret, Johnson, Michael D., Narayanan, Gopal, Raymond, Alexander W., and Tilanus, Remo P. J.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We present a case for significantly enhancing the utility and efficiency of the ngEHT by incorporating an additional 86 GHz observing band. In contrast to 230 or 345 GHz, weather conditions at the ngEHT sites are reliably good enough for 86 GHz to enable year-round observations. Multi-frequency imaging that incorporates 86 GHz observations would sufficiently augment the ($u,v$) coverage at 230 and 345 GHz to permit detection of the M87 jet structure without requiring EHT stations to join the array. The general calibration and sensitivity of the ngEHT would also be enhanced by leveraging frequency phase transfer techniques, whereby simultaneous observations at 86 GHz and higher-frequency bands have the potential to increase the effective coherence times from a few seconds to tens of minutes. When observation at the higher frequencies is not possible, there are opportunities for standalone 86 GHz science, such as studies of black hole jets and spectral lines. Finally, the addition of 86 GHz capabilities to the ngEHT would enable it to integrate into a community of other VLBI facilities $-$ such as the GMVA and ngVLA $-$ that are expected to operate at 86 GHz but not at the higher ngEHT observing frequencies., Comment: 23 pages, 10 figures

Published
2023
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6. The Dense Gas Mass Fraction and the Relationship to Star Formation in M51

Author

Heyer, Mark, Gregg, Benjamin, Calzetti, Daniela, Elmegreen, Bruce G., Kennicutt, Robert, Adamo, Angela, Evans, Aaron S., Grasha, Kathryn, Lowenthal, James D., Narayanan, Gopal, Rosa-Gonzalez, Daniel, Schloerb, F. P., Souccar, Kamal, Tang, Yuping, Teuben, Peter, Vega, Olga, Wall, William F., and Yun, Min S.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Observations of 12CO J=1-0 and HCN J=1-0 emission from NGC 5194 (M51) made with the 50~meter Large Millimeter Telescope and the SEQUOIA focal plane array are presented. Using the HCN to CO ratio, we examine the dense gas mass fraction over a range of environmental conditions within the galaxy. Within the disk, the dense gas mass fraction varies along spiral arms but the average value over all spiral arms is comparable to the mean value of interarm regions. We suggest that the near constant dense gas mass fraction throughout the disk arises from a population of density stratified, self gravitating molecular clouds and the required density threshold to detect each spectral line. The measured dense gas fraction significantly increases in the central bulge in response to the effective pressure, P_e, from the weight from the stellar and gas components. This pressure modifies the dynamical state of the molecular cloud population and possibly, the HCN emitting regions, in the central bulge from self-gravitating to diffuse configurations in which P_e is greater than the gravitational energy density of individual clouds. Diffuse molecular clouds comprise a significant fraction of the molecular gas mass in the central bulge, which may account for the measured sublinear relationships between the surface densities of the star formation rate and molecular and dense gas., Comment: 18 pages, 8 figures, 5 tables. Accepted for publication in ApJ

Published
2022
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7. Event Horizon Telescope observations of the jet launching and collimation in Centaurus A

Author

Janssen, Michael, Falcke, Heino, Kadler, Matthias, Ros, Eduardo, Wielgus, Maciek, Akiyama, Kazunori, Baloković, Mislav, Blackburn, Lindy, Bouman, Katherine L., Chael, Andrew, Chan, Chi-kwan, Chatterjee, Koushik, Davelaar, Jordy, Edwards, Philip G., Fromm, Christian M., Gómez, José L., Goddi, Ciriaco, Issaoun, Sara, Johnson, Michael D., Kim, Junhan, Koay, Jun Yi, Krichbaum, Thomas P., Liu, Jun, Liuzzo, Elisabetta, Markoff, Sera, Markowitz, Alex, Marrone, Daniel P., Mizuno, Yosuke, Müller, Cornelia, Ni, Chunchong, Pesce, Dominic W., Ramakrishnan, Venkatessh, Roelofs, Freek, Rygl, Kazi L. J., van Bemmel, Ilse, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Baczko, Anne-Kathrin, Ball, David, Barrett, John, Benson, Bradford A., Bintley, Dan, Blundell, Raymond, Boland, Wilfred, Bower, Geoffrey C., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Broguiere, Dominique, Bronzwaer, Thomas, Byun, Do-Young, Carlstrom, John E., Chatterjee, Shami, Chen, Ming-Tang, Chen, Yongjun, Chesler, Paul M., Cho, Ilje, Christian, Pierre, Conway, John E., Cordes, James M., Crawford, Thomas M., Crew, Geoffrey B., Cruz-Osorio, Alejandro, Cui, Yuzhu, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Dexter, Jason, Doeleman, Sheperd S., Eatough, Ralph P., Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Ford, H. Alyson, Fraga-Encinas, Raquel, Friberg, Per, Fuentes, Antonio, Galison, Peter, Gammie, Charles F., García, Roberto, Gelles, Zachary, Gentaz, Olivier, Georgiev, Boris, Gold, Roman, Gómez-Ruiz, Arturo I., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Hecht, Michael H., Hesper, Ronald, Himwich, Elizabeth, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Inoue, Makoto, James, David J., Jannuzi, Buell T., Jeter, Britton, Jiang, Wu, Jimenez-Rosales, Alejandra, Jorstad, Svetlana, Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kino, Motoki, Kofuji, Yutaro, Koyama, Shoko, Kramer, Michael, Kramer, Carsten, Kuo, Cheng-Yu, Lauer, Tod R., Lee, Sang-Sung, Levis, Aviad, Li, Yan-Rong, Li, Zhiyuan, Lindqvist, Michael, Lico, Rocco, Lindahl, Greg, Liu, Kuo, Lo, Wen-Ping, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin, Lu, Ru-Sen, MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Marscher, Alan P., Martí-Vidal, Iván, Matsushita, Satoki, Matthews, Lynn D., Medeiros, Lia, Menten, Karl M., Mizuno, Izumi, Moran, James M., Moriyama, Kotaro, Moscibrodzka, Monika, Musoke, Gibwa, Mejías, Alejandro Mus, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayan, Ramesh, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Neilsen, Joey, Neri, Roberto, Noutsos, Aristeidis, Nowak, Michael A., Okino, Hiroki, Olivares, Héctor, Ortiz-León, Gisela N., Oyama, Tomoaki, Özel, Feryal, Palumbo, Daniel C. M., Park, Jongho, Patel, Nimesh, Pen, Ue-Li, Piétu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Pötzl, Felix M., Prather, Ben, Preciado-López, Jorge A., Psaltis, Dimitrios, Pu, Hung-Yi, Rao, Ramprasad, Rawlings, Mark G., Raymond, Alexander W., Rezzolla, Luciano, Ricarte, Angelo, Ripperda, Bart, Rogers, Alan, Rose, Mel, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruszczyk, Chet, Sánchez, Salvador, Sánchez-Arguelles, David, Sasada, Mahito, Savolainen, Tuomas, Schloerb, F. Peter, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Torne, Pablo, Trent, Tyler, Traianou, Efthalia, Trippe, Sascha, van Langevelde, Huib Jan, van Rossum, Daniel R., Wagner, Jan, Ward-Thompson, Derek, Wardle, John, Weintroub, Jonathan, Wex, Norbert, Wharton, Robert, Wong, George N., Wu, Qingwen, Yoon, Doosoo, Young, André, Young, Ken, Younsi, Ziri, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhao, Guang-Yao, and Zhao, Shan-Shan

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

Very-long-baseline interferometry (VLBI) observations of active galactic nuclei at millimeter wavelengths have the power to reveal the launching and initial collimation region of extragalactic radio jets, down to $10-100$ gravitational radii ($r_g=GM/c^2$) scales in nearby sources. Centaurus A is the closest radio-loud source to Earth. It bridges the gap in mass and accretion rate between the supermassive black holes (SMBHs) in Messier 87 and our galactic center. A large southern declination of $-43^{\circ}$ has however prevented VLBI imaging of Centaurus A below ${\lambda}1$cm thus far. Here, we show the millimeter VLBI image of the source, which we obtained with the Event Horizon Telescope at $228$GHz. Compared to previous observations, we image Centaurus A's jet at a tenfold higher frequency and sixteen times sharper resolution and thereby probe sub-lightday structures. We reveal a highly-collimated, asymmetrically edge-brightened jet as well as the fainter counterjet. We find that Centaurus A's source structure resembles the jet in Messier 87 on ${\sim}500r_g$ scales remarkably well. Furthermore, we identify the location of Centaurus A's SMBH with respect to its resolved jet core at ${\lambda}1.3$mm and conclude that the source's event horizon shadow should be visible at THz frequencies. This location further supports the universal scale invariance of black holes over a wide range of masses., Comment: 27 pages, 9 figures. This is a post-peer-review, pre-copyedit version of an article published in Nature Astronomy. The final authenticated version is available online at: https://doi.org/10.1038/s41550-021-01417-w

Published
2021
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8. The Variability of the Black-Hole Image in M87 at the Dynamical Time Scale

Author

Satapathy, Kaushik, Psaltis, Dimitrios, Ozel, Feryal, Medeiros, Lia, Dougall, Sean T., Chan, Chi-kwan, Wielgus, Maciek, Prather, Ben S., Wong, George N., Gammie, Charles F., Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Baczko, Anne-Kathrin, Ball, David R., Baloković, Mislav, Barrett, John, Benson, Bradford A., Bintley, Dan, Blackburn, Lindy, Blundell, Raymond, Boland, Wilfred, Bouman, Katherine L., Bower, Geoffrey C., Boyce, Hope A., Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Broguiere, Dominique, Bronzwaer, Thomas, Bustamente, Sandra, Byun, Do-Young, Carlstrom, John E., Chael, Andrew, Chatterjee, Koushik, Chatterjee, Shami, Chen, Ming-Tang, Chen, Yongjun, Cho, Ilje, Christian, Pierre, Conway, John E., Cordes, James M., Crawford, Thomas, Crew, Geoffrey B., Osorio, Alejandro Cruz, Cui, Yuzhu, Davelaar, Jordy, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica T., Desvignes, Gregory, Dexter, Jason, Doeleman, Sheperd S., Eatough, Ralph, Falcke, Heino, Farah, Joseph R., Fish, Vincent, Fomalont, Edward B., Ford, H. Alyson, Fraga-Encinas, Raquel, Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, García, Roberto, Gentaz, Olivier, Georgiev, Boris, Goddi, Ciriaco, Gold, Roman, Gomez-Ruiz, Arturo I., Gómez, Jose L., Gu, Minfeng, Gurwell, Mark A., Hada, Kazuhiro, Haggard, Daryl, Hecht, Michael, Hesper, Ronald, Ho, Luis C., Ho, Paul T., Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Janssen, Michael, Jeter, Britton, Jiang, Wu, Rosales, Alejandra Jimenez, Johnson, Michael D., Jorstad, Svetlana G., Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kofuji, Yutaro, Koch, Patrick M., Koyama, Shoko, Kramer, Carsten, Kramer, Michael, Krichbaum, Thomas P., Kuo, Cheng-Yu, Lauer, Tod R., Lee, Sang-Sung, Levis, Aviad, Li, Yan-Rong, Li, Zhiyuan, Lindqvist, Michael, Lico, Rocco, Lindahl, Greg, Liu, Jun, Liu, Kuo, Liuzzo, Miss Elisabetta, Lo, Wen-Ping, Lobanov, Andrei, Loinard, Laurent, Lonsdale, Colin J., Lu, Rusen, MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel, Marscher, Alan P., Marti-Vidal, Ivan, Matsushita, Satoki, Matthews, Lynn, Menten, Karl M., Mizuno, Izumi, Mizuno, Yosuke, Moran, James, Moriyama, Kotaro, Moscibrodzka, Monika, Muller, Cornelia, Mejias, Alejandro M., Musoke, Gibwa, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayan, Ramesh, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Neilsen, Joey, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Okino, Hiroki, Olivares, Hector, Ortiz-Leon, Gisela N., Oyama, Tomoaki, Palumbo, Daniel C., Park, Jongho, Patel, Nimesh A., Pen, Ue-Li, Pesce, Dominic W., Pietu, Vincent, Plambeck, Richard L., PopStefanija, Aleksandar, Porth, Oliver, Potzl, Felix, Preciado-López, Jorge A., Pu, Hung-Yi, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark, Raymond, Alexander W., Rezzolla, Luciano, Ripperda, Bart, Roelofs, Freek, Rogers, Alan E. E., Ros, Eduardo, Rose, Mel, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruszczyk, Chet, Rygl, Kazi, Sanchez, Salvador, Sanchez-Arguelles, David, Sasada, Mahito, Savolainen, Tuomas, Schloerb, F Peter, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhi-Qiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo, Titus, Michael, Toma, Kenji, Torne, Pablo, Traianou, E., Trent, Tyler, Trippe, Sascha, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Wagner, Jan, Ward-Thompson, Derek, Wardle, John F., Weintroub, Jonathan, Wex, Norbert, Wharton, Robert, Wiik, Kaj, Wu, Qingwen, Yoon, DooSoo, Young, Andre, Young, Ken H., Younsi, Ziri, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhao, Guang-Yao, and Zhao, Shan-Shan

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The black-hole images obtained with the Event Horizon Telescope (EHT) are expected to be variable at the dynamical timescale near their horizons. For the black hole at the center of the M87 galaxy, this timescale (5-61 days) is comparable to the 6-day extent of the 2017 EHT observations. Closure phases along baseline triangles are robust interferometric observables that are sensitive to the expected structural changes of the images but are free of station-based atmospheric and instrumental errors. We explored the day-to-day variability in closure phase measurements on all six linearly independent non-trivial baseline triangles that can be formed from the 2017 observations. We showed that three triangles exhibit very low day-to-day variability, with a dispersion of $\sim3-5^\circ$. The only triangles that exhibit substantially higher variability ($\sim90-180^\circ$) are the ones with baselines that cross visibility amplitude minima on the $u-v$ plane, as expected from theoretical modeling. We used two sets of General Relativistic magnetohydrodynamic simulations to explore the dependence of the predicted variability on various black-hole and accretion-flow parameters. We found that changing the magnetic field configuration, electron temperature model, or black-hole spin has a marginal effect on the model consistency with the observed level of variability. On the other hand, the most discriminating image characteristic of models is the fractional width of the bright ring of emission. Models that best reproduce the observed small level of variability are characterized by thin ring-like images with structures dominated by gravitational lensing effects and thus least affected by turbulence in the accreting plasmas., Comment: Accepted for Publication in ApJ

Published
2021
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9. Constraints on black-hole charges with the 2017 EHT observations of M87*

Author

Kocherlakota, Prashant, Rezzolla, Luciano, Falcke, Heino, Fromm, Christian M., Kramer, Michael, Mizuno, Yosuke, Nathanail, Antonios, Olivares, Hector, Younsi, Ziri, Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Baczko, Anne-Kathrin, Ball, David, Balokovic, Mislav, Barrett, John, Benson, Bradford A., Bintley, Dan, Blackburn, Lindy, Blundell, Raymond, Boland, Wilfred, Bouman, Katherine L., Bower, Geoffrey C., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Broguiere, Dominique, Bronzwaer, Thomas, Byun, Do-Young, Carlstrom, John E., Chael, Andrew, Chan, Chi-kwan, Chatterjee, Shami, Chatterjee, Koushik, Chen, Ming-Tang, Chen, Yongjun, Chesler, Paul M., Cho, Ilje, Christian, Pierre, Conway, John E., Cordes, James M., Crawford, Thomas M., Crew, Geoffrey B., Cruz-Osorio, Alejandro, Cui, Yuzhu, Davelaar, Jordy, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Doeleman, Sheperd S., Eatough, Ralph P., Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Fraga-Encinas, Raquel, Friberg, Per, Ford, H. Alyson, Fuentes, Antonio, Galison, Peter, Gammie, Charles F., Garcia, Roberto, Gentaz, Olivier, Georgiev, Boris, Goddi, Ciriaco, Gold, Roman, Gomez, Jose L., Gomez-Ruiz, Arturo I., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Hecht, Michael H., Hesper, Ronald, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Janssen, Michael, Jeter, Britton, Jiang, Wu, Jimenez-Rosales, Alejandra, Johnson, Michael D., Jorstad, Svetlana, Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kofuji, Yutaro, Koch, Patrick M., Koyama, Shoko, Kramer, Carsten, Krichbaum, Thomas P., Kuo, Cheng-Yu, Lauer, Tod R., Lee, Sang-Sung, Levis, Aviad, Li, Yan-Rong, Li, Zhiyuan, Lindqvist, Michael, Lico, Rocco, Lindahl, Greg, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lo, Wen-Ping, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin, Lu, Ru-Sen, MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Marti-Vidal, Ivan, Matsushita, Satoki, Matthews, Lynn D., Medeiros, Lia, Menten, Karl M., Mizuno, Izumi, Moran, James M., Moriyama, Kotaro, Moscibrodzka, Monika, Muller, Cornelia, Musoke, Gibwa, Mejias, Alejandro Mus, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayan, Ramesh, Narayanan, Gopal, Natarajan, Iniyan, Neilsen, Joseph, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Okino, Hiroki, Ortiz-Leon, Gisela N., Oyama, Tomoaki, Ozel, Feryal, Palumbo, Daniel C. M., Park, Jongho, Patel, Nimesh, Pen, Ue-Li, Pesce, Dominic W., Pietu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Potzl, Felix M., Prather, Ben, Preciado-Lopez, Jorge A., Psaltis, Dimitrios, Pu, Hung-Yi, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Raymond, Alexander W., Ricarte, Angelo, Ripperda, Bart, Roelofs, Freek, Rogers, Alan, Ros, Eduardo, Rose, Mel, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruszczyk, Chet, Rygl, Kazi L. J., Sanchez, Salvador, Sanchez-Arguelles, David, Sasada, Mahito, Savolainen, Tuomas, Schloerb, F. Peter, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Toma, Kenji, Torne, Pablo, Trent, Tyler, Traianou, Efthalia, Trippe, Sascha, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Wagner, Jan, Ward-Thompson, Derek, Wardle, John, Weintroub, Jonathan, Wex, Norbert, Wharton, Robert, Wielgus, Maciek, Wong, George N., Wu, Qingwen, Yoon, Doosoo, Young, Andre, Young, Ken, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhao, Guang-Yao, Zhao, Shan-Shan, and Collaboration, The EHT

Subjects
General Relativity and Quantum Cosmology
Abstract

Our understanding of strong gravity near supermassive compact objects has recently improved thanks to the measurements made by the Event Horizon Telescope (EHT). We use here the M87* shadow size to infer constraints on the physical charges of a large variety of nonrotating or rotating black holes. For example, we show that the quality of the measurements is already sufficient to rule out that M87* is a highly charged dilaton black hole. Similarly, when considering black holes with two physical and independent charges, we are able to exclude considerable regions of the space of parameters for the doubly-charged dilaton and the Sen black holes., Comment: 15 pages, 4 figures, published in PRD on May 19

Published
2021
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10. The Polarized Image of a Synchrotron Emitting Ring of Gas Orbiting a Black Hole

Author

Narayan, Ramesh, Palumbo, Daniel C. M., Johnson, Michael D., Gelles, Zachary, Himwich, Elizabeth, Chang, Dominic O., Ricarte, Angelo, Dexter, Jason, Gammie, Charles F., Chael, Andrew A., Collaboration, The Event Horizon Telescope, Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Baczko, Anne-Kathrin, Ball, David, Balokovic, Mislav, Barrett, John, Benson, Bradford A., Bintley, Dan, Blackburn, Lindy, Blundell, Raymond, Boland, Wilfred, Bouman, Katherine L., Bower, Geoffrey C., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Broguiere, Dominique, Bronzwaer, Thomas, Byun, Do-Young, Carlstrom, John E., Chan, Chi-kwan, Chatterjee, Shami, Chatterjee, Koushik, Chen, Ming-Tang, Chen, Yongjun, Chesler, Paul M., Cho, Ilje, Christian, Pierre, Conway, John E., Cordes, James M., Crawford, Thomas M., Crew, Geoffrey B., Cruz-Osorio, Alejandro, Cui, Yuzhu, Davelaar, Jordy, DeLaurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Doeleman, Sheperd S., Eatough, Ralph P., Falcke, Heino, Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Ford, H. Alyson, Fraga-Encinas, Raquel, Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, Garcıa, Roberto, Gentaz, Olivier, Georgiev, Boris, Goddi, Ciriaco, Gold, Roman, Gomez, Jose L., Gomez-Ruiz, Arturo I., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Hecht, Michael H., Hesper, Ronald, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Janssen, Michael, Jeter, Britton, Jiang, Wu, Jimenez-Rosales, Alejandra, Jorstad, Svetlana, Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kofuji, Yutaro, Koch, Patrick M., Koyama, Shoko, Kramer, Michael, Kramer, Carsten, Krichbaum, Thomas P., Kuo, Cheng-Yu, Lauer, Tod R., Lee, Sang-Sung, Levis, Aviad, Li, Yan-Rong, Li, Zhiyuan, Lindqvist, Michael, Lico, Rocco, Lindahl, Greg, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lo, Wen-Pin, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin, Lu, Ru-Sen, MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Martı-Vidal, Alan P. Marscher Ivan, Matsushita, Satoki, Matthews, Lynn D., Medeiros, Lia, Menten, Karl M., Mizuno, Izumi, Mizuno, Yosuke, Moran, James M., Moriyama, Kotaro, Moscibrodzka, Monika, Muller, Cornelia, Musoke, Gibwa, Mejıas, Alejandro Mus, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Neilsen, Joey, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Okino, Hiroki, Olivares, Hector, Ortiz-Leon, Gisela N., Oyama, Tomoaki, Ozel, Feryal, Park, Jongho, Patel, Nimesh, Pen, Ue-Li, Pesce, Dominic W., Pietu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Potzl, Felix M., Prather, Ben, Preciado-Lopez, Jorge A., Psaltis, Dimitrios, Pu, Hung-Yi, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Raymond, Alexander W., Rezzolla, Luciano, Ripperda, Bart, Roelofs, Freek, Rogers, Alan, Ros, Eduardo, Rose, Mel, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruszczyk, Chet, Rygl, Kazi L. J., Sanchez, Salvador, Sanchez-Arguelles, David, Sasada, Mahito, Savolainen, Tuomas, Schloerb, F. Peter, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Toma, Kenji, Torne, Pablo, Trent, Tyler, Traianou, Efthalia, Trippe, Sascha, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Wagner, Jan, Ward-Thompson, Derek, Wardle, John, Weintroub, Jonathan, Wex, Norbert, Wharton, Robert, Wielgus, Maciek, Wong, George N., Wu, Qingwen, Yoon, Doosoo, Young, Andre, Young, Ken, Younsi, Ziri, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhao, Guang-Yao, and Zhao, Shan-Shan

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Synchrotron radiation from hot gas near a black hole results in a polarized image. The image polarization is determined by effects including the orientation of the magnetic field in the emitting region, relativistic motion of the gas, strong gravitational lensing by the black hole, and parallel transport in the curved spacetime. We explore these effects using a simple model of an axisymmetric, equatorial accretion disk around a Schwarzschild black hole. By using an approximate expression for the null geodesics derived by Beloborodov (2002) and conservation of the Walker-Penrose constant, we provide analytic estimates for the image polarization. We test this model using currently favored general relativistic magnetohydrodynamic simulations of M87*, using ring parameters given by the simulations. For a subset of these with modest Faraday effects, we show that the ring model broadly reproduces the polarimetric image morphology. Our model also predicts the polarization evolution for compact flaring regions, such as those observed from Sgr A* with GRAVITY. With suitably chosen parameters, our simple model can reproduce the EVPA pattern and relative polarized intensity in Event Horizon Telescope images of M87*. Under the physically motivated assumption that the magnetic field trails the fluid velocity, this comparison is consistent with the clockwise rotation inferred from total intensity images., Comment: 29 pages, 11 figures, published in ApJ on May 3

Published
2021
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11. Star Formation, Observations

Author

Beltrán, Maria Teresa, Narayanan, Gopal, Gargaud, Muriel, editor, Irvine, William M., editor, Amils, Ricardo, editor, Claeys, Philippe, editor, Cleaves, Henderson James, editor, Gerin, Maryvonne, editor, Rouan, Daniel, editor, Spohn, Tilman, editor, Tirard, Stéphane, editor, and Viso, Michel, editor

Published
2023
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12. Gravitational Test Beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole

Author

Psaltis, Dimitrios, Medeiros, Lia, Christian, Pierre, Ozel, Feryal, Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Asada, Keiichi, Azulay, Rebecca, Ball, David, Balokovic, Mislav, Barrett, John, Bintley, Dan, Blackburn, Lindy, Boland, Wilfred, Bower, Geoffrey C., Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broguiere, Dominique, Bronzwaer, Thomas, Byun, Do-Young, Carlstrom, John E., Chael, Andrew, Chan, Chi-kwan, Chatterjee, Shami, Chatterjee, Koushik, Chen, Ming-Tang, Chen, Yongjun, Cho, Ilje, Conway, John E., Cordes, James M., Crew, Geoffrey B., Cui, Yuzhu, Davelaar, Jordy, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Dexter, Jason, Eatough, Ralph P., Falcke, Heino, Fish, Vincent L., Fomalont, Ed, Fraga-Encinas, Raquel, Friberg, Per, Fromm, Christian M., Gammie, Charles F., García, Roberto, Gentaz, Olivier, Goddi, Ciriaco, Gomez, Jose L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Hesper, Ronald, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Janssen, Michael, Jiang, Wu, Jimenez-Rosales, Alejandra, Johnson, Michael D., Jorstad, Svetlana, Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Jae-Young, Kim, Junhan, Kim, Jongsoo, Kino, Motoki, Koay, Jun Yi, Koch, Patrick M., Koyama, Shoko, Kramer, Michael, Kramer, Carsten, Krichbaum, Thomas P., Kuo, Cheng-Yu, Lauer, Tod R., Lee, Sang-Sung, Li, Yan-Rong, Li, Zhiyuan, Lindqvist, Michael, Lico, Rocco, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lo, Wen-Ping, Lobanov, Andrei P., Lonsdale, Colin, Lu, Ru-Sen, Mao, Jirong, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Martí-Vidal, Ivan, Matsushita, Satoki, Mizuno, Yosuke, Mizuno, Izumi, Moran, James M., Moriyama, Kotaro, Moscibrodzka, Monika, Muller, Cornelia, Musoke, Gibwa, Mejías, Alejandro Mus, Nagai, Hiroshi, Nagar, Neil M., Narayan, Ramesh, Narayanan, Gopal, Natarajan, Iniyan, Neri, Roberto, Noutsos, Aristeidis, Okino, Hiroki, Olivares, Hector, Oyama, Tomoaki, Palumbo, Daniel C. M., Park, Jongho, Patel, Nimesh, Pen, Ue-Li, Pietu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Prather, Ben, Preciado-Lopez, Jorge A., Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Raymond, Alexander W., Ripperda, Bart, Roelofs, Freek, Rogers, Alan, Ros, Eduardo, Rose, Mel, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruszczyk, Chet, Ryan, Benjamin R., Rygl, Kazi L. J., Sanchez, Salvador, Sanchez-Arguelles, David, Sasada, Mahito, Savolainen, Tuomas, Schloerb, F. Peter, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Tazaki, Fumie, Tilanus, Remo P. J., Titus, Michael, Torne, Pablo, Trent, Tyler, Traianou, Efthalia, Trippe, Sascha, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Wagner, Jan, Wardle, John, Ward-Thompson, Derek, Weintroub, Jonathan, Wex, Norbert, Wharton, Robert, Wielgus, Maciek, Wong, George N., Wu, Qingwen, Yoon, Doosoo, Young, Andre, Young, Ken, Younsi, Ziri, Yuan, Feng, Yuan, Ye-Fei, Zhao, Shan-Shan, and Collaboration, the EHT

Subjects
General Relativity and Quantum Cosmology, Astrophysics - High Energy Astrophysical Phenomena
Abstract

The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak-field tests can lead to large deviations in the predicted black-hole shadows that are inconsistent with even the current EHT measurements. We use numerical calculations of regular, parametric, non-Kerr metrics to identify the common characteristic among these different parametrizations that control the predicted shadow size. We show that the shadow-size measurements place significant constraints on deviation parameters that control the second post-Newtonian and higher orders of each metric and are, therefore, inaccessible to weak-field tests. The new constraints are complementary to those imposed by observations of gravitational waves from stellar-mass sources., Comment: Physical Review Letters

Published
2020
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13. Studying Black Holes on Horizon Scales with VLBI Ground Arrays

Author

Blackburn, Lindy, Doeleman, Sheperd, Dexter, Jason, Gómez, José L., Johnson, Michael D., Palumbo, Daniel C., Weintroub, Jonathan, Bouman, Katherine L., Chael, Andrew A., Farah, Joseph R., Fish, Vincent, Loinard, Laurent, Lonsdale, Colin, Narayanan, Gopal, Patel, Nimesh A., Pesce, Dominic W., Raymond, Alexander, Tilanus, Remo, Wielgus, Maciek, Akiyama, Kazunori, Bower, Geoffrey, Broderick, Avery, Deane, Roger, Fromm, Christian M., Gammie, Charles, Gold, Roman, Janssen, Michael, Kawashima, Tomohisa, Krichbaum, Thomas, Marrone, Daniel P., Matthews, Lynn D., Mizuno, Yosuke, Rezzolla, Luciano, Roelofs, Freek, Ros, Eduardo, Savolainen, Tuomas K., Yuan, Feng, and Zhao, Guangyao

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

High-resolution imaging of supermassive black holes is now possible, with new applications to testing general relativity and horizon-scale accretion and relativistic jet formation processes. Over the coming decade, the EHT will propose to add new strategically placed VLBI elements operating at 1.3mm and 0.87mm wavelength. In parallel, development of next-generation backend instrumentation, coupled with high throughput correlation architectures, will boost sensitivity, allowing the new stations to be of modest collecting area while still improving imaging fidelity and angular resolution. The goal of these efforts is to move from imaging static horizon scale structure to dynamic reconstructions that capture the processes of accretion and jet launching in near real time., Comment: Astro2020 APC White Paper, 10 pages, 7 figures

Published
2019

14. Studying black holes on horizon scales with space-VLBI

Author

Haworth, Kari, Johnson, Michael D., Pesce, Dominic W., Palumbo, Daniel C. M., Blackburn, Lindy, Akiyama, Kazunori, Boroson, Don, Bouman, Katherine L., Farah, Joseph R., Fish, Vincent L., Honma, Mareki, Kawashima, Tomohisa, Kino, Motoki, Raymond, Alexander, Silver, Mark, Weintroub, Jonathan, Wielgus, Maciek, Doeleman, Sheperd S., Gomez, Jose L., Kauffmann, Jens, Keating, Garrett K., Krichbaum, Thomas P., Loinard, Laurent, Narayanan, Gopal, James, Akihiro Doi David J., Marrone, Daniel P., Mizuno, Yosuke, and Nagai, Hiroshi

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

The Event Horizon Telescope (EHT) recently produced the first horizon-scale image of a supermassive black hole. Expanding the array to include a 3-meter space telescope operating at >200 GHz enables mass measurements of many black holes, movies of black hole accretion flows, and new tests of general relativity that are impossible from the ground.

Published
2019

15. A dusty star-forming galaxy at z=6 revealed by strong gravitational lensing

Author

Zavala, Jorge A., Montaña, Alfredo, Hughes, David H., Yun, Min S., Ivison, R. J., Valiante, Elisabetta, Wilner, David, Spilker, Justin, Aretxaga, Itziar, Eales, Stephen, Avila-Reese, Vladimir, Chávez, Miguel, Cooray, Asantha, Dannerbauer, Helmut, Dunlop, James S., Dunne, Loretta, Gómez-Ruiz, Arturo I., Michalowski, Michal J., Narayanan, Gopal, Nayyeri, Hooshang, Oteo, Ivan, González, Daniel Rosa, Sánchez-Argüelles, David, Serjeant, Stephen, Smith, Matthew W. L., Terlevich, Elena, Vega, Olga, Villalba, Alan, van der Werf, Paul, Wilson, Grant W., and Zeballos, Milagros

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Since their discovery, submillimetre-selected galaxies (SMGs) have revolutionized the field of galaxy formation and evolution. From the hundreds of square degrees mapped at submillimetre wavelengths, only a handful of sources have been confirmed to lie at z>5 and only two at z>6. All of these SMGs are rare examples of extreme starburst galaxies with star formation rates (SFRs) of >1000 M_sun/yr and therefore are not representative of the general population of dusty star-forming galaxies. Consequently, our understanding of the nature of these sources, at the earliest epochs, is still incomplete. Here we report the spectroscopic identification of a gravitationally amplified (mu = 9.3 +/- 1.0) dusty star-forming galaxy at z=6.027. After correcting for gravitational lensing, we derive an intrinsic less-extreme SFR of 380 +/- 50 M_sun/yr for this source and find that its gas and dust properties are similar to those measured for local Ultra Luminous Infrared Galaxies (ULIRGs), extending the local trends to a poorly explored territory in the early Universe. The star-formation efficiency of this galaxy is similar to those measured in its local analogues, despite a ~12 Gyr difference in cosmic time., Comment: Published in Nature Astronomy. This is the author's version of the accepted paper (posted 6 months after publication in accordance with Nature policy). The published version is available at https://www.nature.com/articles/s41550-017-0297-8

Published
2017
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16. An in vitro evaluation of canal transportation and centering ability of ProTaper Universal, Hyflex EDM, and WaveOne gold using microcomputed tomography

Author

Ashwin Ravichandran, Veni Ashok Baskaran, Shankar Narayanan Gopal, Venkatesan S Motilal, Meenakshisundram Rajasekaran, and Anil Kumar Ramachandran

Subjects
canal transportation, centering ability, microcomputed tomography, Dentistry, RK1-715
Abstract

Aim: The study was to determine and compare the values of canal transportation and centering ability of ProTaper Universal (PTU), Hyflex EDM (HEDM), and WaveOne GOLD (WOG) using microcomputed tomography (Micro-CT). Methods: Sixty mandibular molar mesiobuccal canals were randomly allocated into three groups, each with 20 samples: PTU (group one), HEDM (group two), and WOG (group three). Micro-CT was used to scan samples before and after instrumentation. Three-dimensional scans of root cross-sections at 3 mm, 6 mm, and 9 mm from the apex were obtained to measure canal transportation and centering ability. For statistical analysis, SPSS software was utilized. P = 0.05 was used as the significance level. Results: When compared all three systems, PTU files had the highest transportation and were less centered. HEDM and WOG showed no significant difference (P > 0.05). Conclusion: Curved roots canals were shaped without any significant canal transportation by Hyflex EDM and WOG when compared with PTU files.

Published
2022
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17. Synthesis and characterization of nisin-incorporated alpha-tricalcium phosphate for pulp capping – An in vitro study

Author

Veni Ashok Baskaran, Manavalan Madhana Madhubala, Thangam Menon, Shankar Narayanan Gopal, and S M Venkatesan

Subjects
alpha-tricalcium phosphate, dentin, nisin, pulp capping, Dentistry, RK1-715
Abstract

Aim: The present study aimed to synthesize and characterize Nisin incorporated Alpha Tricalcium Phosphate (NTCP) and to evaluate nisin release from NTCP when used as a pulp capping agent. Methods: Alpha TCP(aTCP) powder was synthesized by the wet chemical method. Nisin was incorporated into this prepared aTCP at various ratios and grouped as follows: Group 1 - 1% wt%; Group 2 -2.5wt%; Group 3-5%wt%; Group 4- 7.5%wt%; Group 5 -10%wt% ; Group 6 -Nisin 100 mg; All these samples were characterized using Fourier Transmission Infrared Spectroscopy(FTIR) and Differential Scanning Calorimetry (DSC). For evaluation of nisin release from NTCP using HPLC, around fifteen freshly extracted non-carious human third molars were collected and mounted in gypsum blocks. A standard box-type class-I cavity (4.5x 4.5 mm) was prepared with the pulpal floor ending at deep dentin, The experimental materials were mixed with propylene glycol to prepare it as pulp capping material in paste form. Subsequently pulpal floor of all the cavities were lined with the respective materials. The entire samples were kept to set for 30 minutes in ambient temperature and subsequently immersed in water and stored in an incubator at 37oC. After 14 days of immersion, dentin lying directly below the sample was cut and powdered using mortar and pestle. The powdered dentin was then subjected to HPLC analysis. The peak time of nisin release from experimental groups was recorded. Results: FTIR results revealed Group 5 with highly appreciable corresponding bends of amine N-H, C-H stretching and phosphate peaks at 1100 and 554 close to Control TCP samples. DSC analysis showed that TCP did not change from 30oC to 80oC and sample 1, 2, 3,and 4, did not show any denaturation point. Sample 5 showed denaturation point slightly above the denaturation temperature of nisin. On HPLC analysis, samples 4 and 5 showed higher peaks of nisin release and traces of nisin release from all the groups. Conclusion: Within the limitations of this study, it can be concluded that NTCP can be synthesized successfully without any influence on the properties of each other material. 10% NTCP provides higher release into dentinal tubules when used as a pulp capping agent.

Published
2022
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18. The Intrinsic Shape of Sagittarius A* at 3.5-mm Wavelength

Author

Ortiz-León, Gisela N., Johnson, Michael D., Doeleman, Sheperd S., Blackburn, Lindy, Fish, Vincent L., Loinard, Laurent, Reid, Mark J., Castillo, Edgar, Chael, Andrew A., Hernández-Gómez, Antonio, Hughes, David, León-Tavares, Jonathan, Lu, Ru-Sen, Montaña, Alfredo, Narayanan, Gopal, Rosenfeld, Katherine, Sánchez, David, Schloerb, F. Peter, Shen, Zhi-qiang, Shiokawa, Hotaka, SooHoo, Jason, and Vertatschitsch, Laura

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The radio emission from Sgr A$^\ast$ is thought to be powered by accretion onto a supermassive black hole of $\sim\! 4\times10^6~ \rm{M}_\odot$ at the Galactic Center. At millimeter wavelengths, Very Long Baseline Interferometry (VLBI) observations can directly resolve the bright innermost accretion region of Sgr A$^\ast$. Motivated by the addition of many sensitive, long baselines in the north-south direction, we developed a full VLBI capability at the Large Millimeter Telescope Alfonso Serrano (LMT). We successfully detected Sgr A$^\ast$ at 3.5~mm with an array consisting of 6 Very Long Baseline Array telescopes and the LMT. We model the source as an elliptical Gaussian brightness distribution and estimate the scattered size and orientation of the source from closure amplitude and self-calibration analysis, obtaining consistent results between methods and epochs. We then use the known scattering kernel to determine the intrinsic two dimensional source size at 3.5 mm: $(147\pm7~\mu\rm{as}) \times (120\pm12~\mu\rm{as})$, at position angle $88^\circ\pm7^\circ$ east of north. Finally, we detect non-zero closure phases on some baseline triangles, but we show that these are consistent with being introduced by refractive scattering in the interstellar medium and do not require intrinsic source asymmetry to explain., Comment: 10 pages, 8 figures, accepted for publication in ApJ

Published
2016
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20. Early Science with the Large Millimeter Telescope: COOL BUDHIES I - a pilot study of molecular and atomic gas at z~0.2

Author

Cybulski, Ryan, Yun, Min S., Erickson, Neal, De la Luz, Victor, Narayanan, Gopal, Montaña, Alfredo, Sánchez-Argülles, David, Zavala, Jorge A., Zeballos, Milagros, Chung, Aeree, Fernández, Ximena, van Gorkom, Jacqueline, Haines, Chris P., Jaffé, Yara L., Montero-Castaño, María, Poggianti, Bianca M., Verheijen, Marc A. W., Yoon, Hyein, Harrington, Kevin, Hughes, David H., Morrison, Glenn E., Schloerb, F. Peter, and Velazquez, Miguel

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

An understanding of the mass build-up in galaxies over time necessitates tracing the evolution of cold gas (molecular and atomic) in galaxies. To that end, we have conducted a pilot study called CO Observations with the LMT of the Blind Ultra-Deep H I Environment Survey (COOL BUDHIES). We have observed 23 galaxies in and around the two clusters Abell 2192 (z = 0.188) and Abell 963 (z = 0.206), where 12 are cluster members and 11 are slightly in the foreground or background, using about 28 total hours on the Redshift Search Receiver (RSR) on the Large Millimeter Telescope (LMT) to measure the $^{12}$CO J = 1 --> 0 emission line and obtain molecular gas masses. These new observations provide a unique opportunity to probe both the molecular and atomic components of galaxies as a function of environment beyond the local Universe. For our sample of 23 galaxies, nine have reliable detections (S/N$\geq$3.6) of the $^{12}$CO line, and another six have marginal detections (2.0 < S/N < 3.6). For the remaining eight targets we can place upper limits on molecular gas masses roughly between $10^9$ and $10^{10} M_\odot$. Comparing our results to other studies of molecular gas, we find that our sample is significantly more abundant in molecular gas overall, when compared to the stellar and the atomic gas component, and our median molecular gas fraction lies about $1\sigma$ above the upper limits of proposed redshift evolution in earlier studies. We discuss possible reasons for this discrepancy, with the most likely conclusion being target selection and Eddington bias., Comment: MNRAS, submitted

Published
2015
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21. Early Science with the Large Millimeter Telescope: Exploring the Effect of AGN Activity on the Relationships Between Molecular Gas, Dust, and Star Formation

Author

Kirkpatrick, Allison, Pope, Alex, Aretxaga, Itziar, Armus, Lee, Calzetti, Daniela, Helou, George, Montana, Alfredo, Narayanan, Gopal, Schloerb, F. Peter, Shi, Yong, Vega, Olga, and Yun, Min

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

The molecular gas, H$_2$, that fuels star formation in galaxies is difficult to observe directly. As such, the ratio of $L_{\rm IR}$ to $L^\prime_{\rm CO}$ is an observational estimation of the star formation rate compared with the amount of molecular gas available to form stars, which is related to the star formation efficiency and the inverse of the gas consumption timescale. We test what effect an IR luminous AGN has on the ratio $L_{\rm IR}/L^\prime_{\rm CO}$ in a sample of 24 intermediate redshift galaxies from the 5 mJy Unbiased Spitzer Extragalactic Survey (5MUSES). We obtain new CO(1-0) observations with the Redshift Search Receiver on the Large Millimeter Telescope. We diagnose the presence and strength of an AGN using Spitzer IRS spectroscopy. We find that removing the AGN contribution to $L_{\rm IR}^{\rm tot}$ results in a mean $L_{\rm IR}^{\rm SF}/L^\prime_{\rm CO}$ for our entire sample consistent with the mean $L_{\rm IR}/L^\prime_{\rm CO}$ derived for a large sample of star forming galaxies from $z\sim0-3$. We also include in our comparison the relative amount of polycyclic aromatic hydrocarbon emission for our sample and a literature sample of local and high redshift Ultra Luminous Infrared Galaxies and find a consistent trend between $L_{6.2}/L_{\rm IR}^{\rm SF}$ and $L_{\rm IR}^{\rm SF}/L^\prime_{\rm CO}$, such that small dust grain emission decreases with increasing $L_{\rm IR}^{\rm SF}/L^\prime_{\rm CO}$ for both local and high redshift dusty galaxies., Comment: Accepted for publication in ApJ (to appear on December 10)

Published
2014
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22. Molecular Outflows Identified in the FCRAO CO Survey of the Taurus Molecular Cloud

Author

Narayanan, Gopal, Snell, Ronald, and Bemis, Ashley

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

The 100 square degree FCRAO CO survey of the Taurus molecular cloud provides an excellent opportunity to undertake an unbiased survey of a large, nearby, molecular cloud complex for molecular outflow activity. Our study provides information on the extent, energetics and frequency of outflows in this region, which are then used to assess the impact of outflows on the parent molecular cloud. The search identified 20 outflows in the Taurus region, 8 of which were previously unknown. Both $^{12}$CO and $^{13}$CO data cubes from the Taurus molecular map were used, and dynamical properties of the outflows are derived. Even for previously known outflows, our large-scale maps indicate that many of the outflows are much larger than previously suspected, with eight of the flows (40%) being more than a parsec long. The mass, momentum and kinetic energy from the 20 outflows are compared to the repository of turbulent energy in Taurus. Comparing the energy deposition rate from outflows to the dissipation rate of turbulence, we conclude that outflows by themselves cannot sustain the observed turbulence seen in the entire cloud. However, when the impact of outflows is studied in selected regions of Taurus, it is seen that locally, outflows can provide a significant source of turbulence and feedback. Five of the eight newly discovered outflows have no known associated stellar source, indicating that they may be embedded Class 0 sources. In Taurus, 30% of Class I sources and 12% of Flat spectrum sources from the Spitzer YSO catalogue have outflows, while 75% of known Class 0 objects have outflows. Overall, the paucity of outflows in Taurus compared to the embedded population of Class I and Flat Spectrum YSOs indicate that molecular outflows are a short-lived stage marking the youngest phase of protostellar life., Comment: Accepted for publication in MNRAS; 28 pages, 60 figures, 5 tables. For full abstract, see paper

Published
2012
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23. The Redshift Search Receiver 3 mm Wavelength Spectra of 10 Galaxies

Author

Snell, Ronald L., Narayanan, Gopal, Yun, Min S., Heyer, Mark, Chung, Aeree, Irvine, William M., Erickson, Neal R., and Liu, Guilin

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

The 3 mm wavelength spectra of 10 galaxies have been obtained at the Five College Radio Astronomy Observatory using a new, very broadband receiver and spectrometer, called the Redshift Search Receiver (RSR). The RSR has an instantaneous bandwidth of 37 GHz covering frequencies from 74 to 111 GHz, and has a spectral resolution of 31 MHz (~100 km/s). During tests of the RSR on the FCRAO 14 m telescope the complete 3 mm spectra of the central regions of NGC 253, Maffei 2, NGC1068, IC 342, M82, NGC 3079, NGC 3690, NGC 4258, Arp 220 and NGC 6240 were obtained. Within the wavelength band covered by the RSR, 20 spectral lines from 14 different atomic and molecular species were detected. Based on simultaneous fits to the spectrum of each galaxy, a number of key molecular line ratios are derived. A simple model which assumes the emission arises from an ensemble of Milky Way-like Giant Nolecular Cloud cores can adequately fit the observed line ratios using molecular abundances based on Galactic molecular cloud cores. Variations seen in some line ratios, such as 13CO/HCN and HCO+/HCN, can be explained if the mean density of the molecular gas varies from galaxy to galaxy. However, NGC 3690, NGC 4258 and NGC 6240 show very large HCO+/HCN ratios and require significant abundance enhancement of HCO+ over HCN, possible due to the proximity to active galactic nucleus activity. Finally, the mass of dense molecular gas is estimated and we infer that 25-85 % of the total molecular gas in the central regions of these galaxies must have densities greater than 10^4 cm^-3., Comment: accepted for publication in A.J

Published
2010
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24. The Redshift Search Receiver Observations of 12CO J=1-->0 in 29 Ultraluminous Infrared Galaxies

Author

Chung, Aeree, Narayanan, Gopal, Yun, Min S., Heyer, Mark, and Erickson, Neal R.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present 12CO J=1-->0 observations of ultraluminous infrared galaxies (ULIRGs) obtained using the Redshift Search Receiver (RSR) on the 14-m telescope of the Five College Radio Astronomy Observatory. The RSR is a novel, dual-beam, dual-polarization receiver equipped with an ultra-wideband spectrometer backend that is being built as a facility receiver for the Large Millimeter Telescope. Our sample consists of 29 ULIRGs in the redshift range of 0.04-0.11, including 10 objects with no prior 12CO measurements. We have detected 27 systems (a detection rate of 93%), including 9 ULIRGs that are detected in CO for the first time. Our study has increased the number of local ULIRGs with CO measurements by ~15%. The CO line luminosity L'_CO, correlates well with far-infrared luminosity L_FIR, following the general trend of other local ULIRGs. However, compared to previous surveys we probe deeper into the low CO luminosity end of ULIRG population as a single study by including a number of CO faint objects in the sample. As a result, we find 1) a smoother transition between the ULIRG population and local QSOs in L_FIR-L'_CO ("star formation efficiency") space, and 2) a broader range of L_FIR/L'_CO flux ratio (~60--1000 L_sun/[K km/s/pc^2]) than previously reported. In our new survey, we also have found a small number of ULIRGs with extreme L_FIR/L'_CO which had been known to be rare. The mid-IR color and radio-excess of 56 local ULIRGs as a function of FIR-to-CO flux ratio is examined and compared with those of spirals/starburst galaxies and low-z QSOs. In this paper, using a large sample of local ULIRGs we explore the origin of their current power source and potential evolution to QSOs., Comment: 16 pages, 12 figures; accepted for publication in the Astronomical Journal

Published
2009
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25. A Search for Pulsars around Sgr A* in the First Event Horizon Telescope Data Set

Author

Torne, Pablo, primary, Liu, Kuo, additional, Eatough, Ralph P., additional, Wongphechauxsorn, Jompoj, additional, Cordes, James M., additional, Desvignes, Gregory, additional, De Laurentis, Mariafelicia, additional, Kramer, Michael, additional, Ransom, Scott M., additional, Chatterjee, Shami, additional, Wharton, Robert, additional, Karuppusamy, Ramesh, additional, Blackburn, Lindy, additional, Janssen, Michael, additional, Chan, Chi-kwan, additional, Crew, Geoffrey, B., additional, Matthews, Lynn D., additional, Goddi, Ciriaco, additional, Rottmann, Helge, additional, Wagner, Jan, additional, Sánchez, Salvador, additional, Ruiz, Ignacio, additional, Abbate, Federico, additional, Bower, Geoffrey C., additional, Salamanca, Juan J., additional, Gómez-Ruiz, Arturo I., additional, Herrera-Aguilar, Alfredo, additional, Jiang 江, Wu 悟, additional, Lu 路, Ru-Sen 如森, additional, Pen, Ue-Li, additional, Raymond, Alexander W., additional, Shao, Lijing, additional, Shen 沈, Zhiqiang 志强, additional, Paubert, Gabriel, additional, Sanchez-Portal, Miguel, additional, Kramer, Carsten, additional, Castillo, Manuel, additional, Navarro, Santiago, additional, John, David, additional, Schuster, Karl-Friedrich, additional, Johnson, Michael D., additional, Rygl, Kazi L. J., additional, Akiyama, Kazunori, additional, Alberdi, Antxon, additional, Alef, Walter, additional, Algaba, Juan Carlos, additional, Anantua, Richard, additional, Asada, Keiichi, additional, Azulay, Rebecca, additional, Bach, Uwe, additional, Baczko, Anne-Kathrin, additional, Ball, David, additional, Baloković, Mislav, additional, Barrett, John, additional, Bauböck, Michi, additional, Benson, Bradford A., additional, Bintley, Dan, additional, Blundell, Raymond, additional, Bouman, Katherine L., additional, Boyce, Hope, additional, Bremer, Michael, additional, Brinkerink, Christiaan D., additional, Brissenden, Roger, additional, Britzen, Silke, additional, Broderick, Avery E., additional, Broguiere, Dominique, additional, Bronzwaer, Thomas, additional, Bustamante, Sandra, additional, Byun, Do-Young, additional, Carlstrom, John E., additional, Ceccobello, Chiara, additional, Chael, Andrew, additional, Chang, Dominic O., additional, Chatterjee, Koushik, additional, Chen, Ming-Tang, additional, Chen 陈, Yongjun 永军, additional, Cheng, Xiaopeng, additional, Cho, Ilje, additional, Christian, Pierre, additional, Conroy, Nicholas S., additional, Conway, John E., additional, Crawford, Thomas M., additional, Cruz-Osorio, Alejandro, additional, Cui 崔, Yuzhu 玉竹, additional, Dahale, Rohan, additional, Davelaar, Jordy, additional, Deane, Roger, additional, Dempsey, Jessica, additional, Dexter, Jason, additional, Dhruv, Vedant, additional, Doeleman, Sheperd S., additional, Dougal, Sean, additional, Dzib, Sergio A., additional, Emami, Razieh, additional, Falcke, Heino, additional, Farah, Joseph, additional, Fish, Vincent L., additional, Fomalont, Ed, additional, Ford, H. Alyson, additional, Foschi, Marianna, additional, Fraga-Encinas, Raquel, additional, Freeman, William T., additional, Friberg, Per, additional, Fromm, Christian M., additional, Fuentes, Antonio, additional, Galison, Peter, additional, Gammie, Charles F., additional, García, Roberto, additional, Gentaz, Olivier, additional, Georgiev, Boris, additional, Gold, Roman, additional, Gómez, José L., additional, Gu 顾, Minfeng 敏峰, additional, Gurwell, Mark, additional, Hada, Kazuhiro, additional, Haggard, Daryl, additional, Haworth, Kari, additional, Hecht, Michael H., additional, Hesper, Ronald, additional, Heumann, Dirk, additional, Ho 何, Luis C. 子山, additional, Ho, Paul, additional, Honma, Mareki, additional, Huang, Chih-Wei L., additional, Huang 黄, Lei 磊, additional, Hughes, David H., additional, Ikeda, Shiro, additional, Impellizzeri, C. M. Violette, additional, Inoue, Makoto, additional, Issaoun, Sara, additional, James, David J., additional, Jannuzi, Buell T., additional, Jeter, Britton, additional, Jiménez-Rosales, Alejandra, additional, Jorstad, Svetlana, additional, Joshi, Abhishek V., additional, Jung, Taehyun, additional, Karami, Mansour, additional, Kawashima, Tomohisa, additional, Keating, Garrett K., additional, Kettenis, Mark, additional, Kim, Dong-Jin, additional, Kim, Jae-Young, additional, Kim, Jongsoo, additional, Kim, Junhan, additional, Kino, Motoki, additional, Koay, Jun Yi, additional, Kocherlakota, Prashant, additional, Kofuji, Yutaro, additional, Koyama, Shoko, additional, Krichbaum, Thomas P., additional, Kuo, Cheng-Yu, additional, La Bella, Noemi, additional, Lauer, Tod R., additional, Lee, Daeyoung, additional, Lee, Sang-Sung, additional, Leung, Po Kin, additional, Levis, Aviad, additional, Li 李, Zhiyuan 志远, additional, Lico, Rocco, additional, Lindahl, Greg, additional, Lindqvist, Michael, additional, Lisakov, Mikhail, additional, Liu 刘, Jun 俊, additional, Liuzzo, Elisabetta, additional, Lo, Wen-Ping, additional, Lobanov, Andrei P., additional, Loinard, Laurent, additional, Lonsdale, Colin J., additional, MacDonald, Nicholas R., additional, Mao 毛, Jirong 基荣, additional, Marchili, Nicola, additional, Markoff, Sera, additional, Marrone, Daniel P., additional, Marscher, Alan P., additional, Martí-Vidal, Iván, additional, Matsushita, Satoki, additional, Medeiros, Lia, additional, Menten, Karl M., additional, Michalik, Daniel, additional, Mizuno, Izumi, additional, Mizuno, Yosuke, additional, Moran, James M., additional, Moriyama, Kotaro, additional, Moscibrodzka, Monika, additional, Müller, Cornelia, additional, Müller, Hendrik, additional, Mus, Alejandro, additional, Musoke, Gibwa, additional, Myserlis, Ioannis, additional, Nadolski, Andrew, additional, Nagai, Hiroshi, additional, Nagar, Neil M., additional, Nakamura, Masanori, additional, Narayan, Ramesh, additional, Narayanan, Gopal, additional, Natarajan, Iniyan, additional, Nathanail, Antonios, additional, Neilsen, Joey, additional, Neri, Roberto, additional, Ni, Chunchong, additional, Noutsos, Aristeidis, additional, Nowak, Michael A., additional, Oh, Junghwan, additional, Okino, Hiroki, additional, Olivares, Héctor, additional, Ortiz-León, Gisela N., additional, Oyama, Tomoaki, additional, Özel, Feryal, additional, Palumbo, Daniel C. M., additional, Paraschos, Georgios Filippos, additional, Park, Jongho, additional, Parsons, Harriet, additional, Patel, Nimesh, additional, Pesce, Dominic W., additional, Piétu, Vincent, additional, Plambeck, Richard, additional, PopStefanija, Aleksandar, additional, Porth, Oliver, additional, Pötzl, Felix M., additional, Prather, Ben, additional, Preciado-López, Jorge A., additional, Psaltis, Dimitrios, additional, Pu, Hung-Yi, additional, Ramakrishnan, Venkatessh, additional, Rao, Ramprasad, additional, Rawlings, Mark G., additional, Rezzolla, Luciano, additional, Ricarte, Angelo, additional, Ripperda, Bart, additional, Roelofs, Freek, additional, Rogers, Alan, additional, Ros, Eduardo, additional, Romero-Cañizales, Cristina, additional, Roshanineshat, Arash, additional, Roy, Alan L., additional, Ruszczyk, Chet, additional, Sánchez-Argüelles, David, additional, Sasada, Mahito, additional, Satapathy, Kaushik, additional, Savolainen, Tuomas, additional, Schloerb, F. Peter, additional, Schonfeld, Jonathan, additional, Small, Des, additional, Sohn, Bong Won, additional, SooHoo, Jason, additional, Souccar, Kamal, additional, Sun 孙, He 赫, additional, Tetarenko, Alexandra J., additional, Tiede, Paul, additional, Tilanus, Remo P. J., additional, Titus, Michael, additional, Toscano, Teresa, additional, Traianou, Efthalia, additional, Trent, Tyler, additional, Trippe, Sascha, additional, Turk, Matthew, additional, van Bemmel, Ilse, additional, van Langevelde, Huib Jan, additional, van Rossum, Daniel R., additional, Vos, Jesse, additional, Ward-Thompson, Derek, additional, Wardle, John, additional, Weintroub, Jonathan, additional, Wex, Norbert, additional, Wielgus, Maciek, additional, Wiik, Kaj, additional, Witzel, Gunther, additional, Wondrak, Michael F., additional, Wong, George N., additional, Wu 吴, Qingwen 庆文, additional, Yadlapalli, Nitika, additional, Yamaguchi, Paul, additional, Yfantis, Aristomenis, additional, Yoon, Doosoo, additional, Young, André, additional, Young, Ken, additional, Younsi, Ziri, additional, Yu 于, Wei 威, additional, Yuan 袁, Feng 峰, additional, Yuan 袁, Ye-Fei 业飞, additional, Zensus, J. Anton, additional, Zhang, Shuo, additional, Zhao, Guang-Yao, additional, and Zhao 赵, Shan-Shan 杉杉, additional

Published
2023
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26. Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes

Author

Roelofs, Freek, primary, Johnson, Michael D., additional, Chael, Andrew, additional, Janssen, Michael, additional, Wielgus, Maciek, additional, Broderick, Avery E., additional, Akiyama, Kazunori, additional, Alberdi, Antxon, additional, Alef, Walter, additional, Algaba, Juan Carlos, additional, Anantua, Richard, additional, Asada, Keiichi, additional, Azulay, Rebecca, additional, Bach, Uwe, additional, Baczko, Anne-Kathrin, additional, Ball, David, additional, Baloković, Mislav, additional, Barrett, John, additional, Bauböck, Michi, additional, Benson, Bradford A., additional, Bintley, Dan, additional, Blackburn, Lindy, additional, Blundell, Raymond, additional, Bouman, Katherine L., additional, Bower, Geoffrey C., additional, Boyce, Hope, additional, Bremer, Michael, additional, Brinkerink, Christiaan D., additional, Brissenden, Roger, additional, Britzen, Silke, additional, Broguiere, Dominique, additional, Bronzwaer, Thomas, additional, Bustamante, Sandra, additional, Byun, Do-Young, additional, Carlstrom, John E., additional, Ceccobello, Chiara, additional, Chan, Chi-kwan, additional, Chang, Dominic O., additional, Chatterjee, Koushik, additional, Chatterjee, Shami, additional, Chen, Ming-Tang, additional, Chen 陈, Yongjun 永军, additional, Cheng, Xiaopeng, additional, Cho, Ilje, additional, Christian, Pierre, additional, Conroy, Nicholas S., additional, Conway, John E., additional, Cordes, James M., additional, Crawford, Thomas M., additional, Crew, Geoffrey B., additional, Cruz-Osorio, Alejandro, additional, Cui 崔, Yuzhu 玉竹, additional, Dahale, Rohan, additional, Davelaar, Jordy, additional, De Laurentis, Mariafelicia, additional, Deane, Roger, additional, Dempsey, Jessica, additional, Desvignes, Gregory, additional, Dexter, Jason, additional, Dhruv, Vedant, additional, Doeleman, Sheperd S., additional, Dougal, Sean, additional, Dzib, Sergio A., additional, Eatough, Ralph P., additional, Emami, Razieh, additional, Falcke, Heino, additional, Farah, Joseph, additional, Fish, Vincent L., additional, Fomalont, Ed, additional, Ford, H. Alyson, additional, Foschi, Marianna, additional, Fraga-Encinas, Raquel, additional, Freeman, William T., additional, Friberg, Per, additional, Fromm, Christian M., additional, Fuentes, Antonio, additional, Galison, Peter, additional, Gammie, Charles F., additional, García, Roberto, additional, Gentaz, Olivier, additional, Georgiev, Boris, additional, Goddi, Ciriaco, additional, Gold, Roman, additional, Gómez-Ruiz, Arturo I., additional, Gómez, José L., additional, Gu 顾, Minfeng 敏峰, additional, Gurwell, Mark, additional, Hada, Kazuhiro, additional, Haggard, Daryl, additional, Haworth, Kari, additional, Hecht, Michael H., additional, Hesper, Ronald, additional, Heumann, Dirk, additional, Ho 何, Luis C. 子山, additional, Ho, Paul, additional, Honma, Mareki, additional, Huang, Chih-Wei L., additional, Huang 黄, Lei 磊, additional, Hughes, David H., additional, Ikeda, Shiro, additional, Impellizzeri, C. M. Violette, additional, Inoue, Makoto, additional, Issaoun, Sara, additional, James, David J., additional, Jannuzi, Buell T., additional, Jeter, Britton, additional, Jiang 江, Wu 悟, additional, Jiménez-Rosales, Alejandra, additional, Jorstad, Svetlana, additional, Joshi, Abhishek V., additional, Jung, Taehyun, additional, Karami, Mansour, additional, Karuppusamy, Ramesh, additional, Kawashima, Tomohisa, additional, Keating, Garrett K., additional, Kettenis, Mark, additional, Kim, Dong-Jin, additional, Kim, Jae-Young, additional, Kim, Jongsoo, additional, Kim, Junhan, additional, Kino, Motoki, additional, Koay, Jun Yi, additional, Kocherlakota, Prashant, additional, Kofuji, Yutaro, additional, Koch, Patrick M., additional, Koyama, Shoko, additional, Kramer, Carsten, additional, Kramer, Joana A., additional, Kramer, Michael, additional, Krichbaum, Thomas P., additional, Kuo, Cheng-Yu, additional, La Bella, Noemi, additional, Lauer, Tod R., additional, Lee, Daeyoung, additional, Lee, Sang-Sung, additional, Leung, Po Kin, additional, Levis, Aviad, additional, Li 李, Zhiyuan 志远, additional, Lico, Rocco, additional, Lindahl, Greg, additional, Lindqvist, Michael, additional, Lisakov, Mikhail, additional, Liu 刘, Jun 俊, additional, Liu, Kuo, additional, Liuzzo, Elisabetta, additional, Lo, Wen-Ping, additional, Lobanov, Andrei P., additional, Loinard, Laurent, additional, Lonsdale, Colin J., additional, Lowitz, Amy E., additional, Lu 路, Ru-Sen 如森, additional, MacDonald, Nicholas R., additional, Mao 毛, Jirong 基荣, additional, Marchili, Nicola, additional, Markoff, Sera, additional, Marrone, Daniel P., additional, Marscher, Alan P., additional, Martí-Vidal, Iván, additional, Matsushita, Satoki, additional, Matthews, Lynn D., additional, Medeiros, Lia, additional, Menten, Karl M., additional, Michalik, Daniel, additional, Mizuno, Izumi, additional, Mizuno, Yosuke, additional, Moran, James M., additional, Moriyama, Kotaro, additional, Moscibrodzka, Monika, additional, Mulaudzi, Wanga, additional, Müller, Cornelia, additional, Müller, Hendrik, additional, Mus, Alejandro, additional, Musoke, Gibwa, additional, Myserlis, Ioannis, additional, Nadolski, Andrew, additional, Nagai, Hiroshi, additional, Nagar, Neil M., additional, Nakamura, Masanori, additional, Narayan, Ramesh, additional, Narayanan, Gopal, additional, Natarajan, Iniyan, additional, Nathanail, Antonios, additional, Fuentes, Santiago Navarro, additional, Neilsen, Joey, additional, Neri, Roberto, additional, Ni, Chunchong, additional, Noutsos, Aristeidis, additional, Nowak, Michael A., additional, Oh, Junghwan, additional, Okino, Hiroki, additional, Olivares, Héctor, additional, Ortiz-León, Gisela N., additional, Oyama, Tomoaki, additional, Özel, Feryal, additional, Palumbo, Daniel C. M., additional, Paraschos, Georgios Filippos, additional, Park, Jongho, additional, Parsons, Harriet, additional, Patel, Nimesh, additional, Pen, Ue-Li, additional, Pesce, Dominic W., additional, Piétu, Vincent, additional, Plambeck, Richard, additional, PopStefanija, Aleksandar, additional, Porth, Oliver, additional, Pötzl, Felix M., additional, Prather, Ben, additional, Preciado-López, Jorge A., additional, Psaltis, Dimitrios, additional, Pu, Hung-Yi, additional, Ramakrishnan, Venkatessh, additional, Rao, Ramprasad, additional, Rawlings, Mark G., additional, Raymond, Alexander W., additional, Rezzolla, Luciano, additional, Ricarte, Angelo, additional, Ripperda, Bart, additional, Rogers, Alan, additional, Romero-Cañizales, Cristina, additional, Ros, Eduardo, additional, Roshanineshat, Arash, additional, Rottmann, Helge, additional, Roy, Alan L., additional, Ruiz, Ignacio, additional, Ruszczyk, Chet, additional, Rygl, Kazi L. J., additional, Sánchez, Salvador, additional, Sánchez-Argüelles, David, additional, Sánchez-Portal, Miguel, additional, Sasada, Mahito, additional, Satapathy, Kaushik, additional, Savolainen, Tuomas, additional, Schloerb, F. Peter, additional, Schonfeld, Jonathan, additional, Schuster, Karl-Friedrich, additional, Shao, Lijing, additional, Shen 沈, Zhiqiang 志强, additional, Small, Des, additional, Sohn, Bong Won, additional, SooHoo, Jason, additional, Sosapanta Salas, León David, additional, Souccar, Kamal, additional, Sun 孙, He 赫, additional, Tazaki, Fumie, additional, Tetarenko, Alexandra J., additional, Tiede, Paul, additional, Tilanus, Remo P. J., additional, Titus, Michael, additional, Torne, Pablo, additional, Toscano, Teresa, additional, Traianou, Efthalia, additional, Trent, Tyler, additional, Trippe, Sascha, additional, Turk, Matthew, additional, van Bemmel, Ilse, additional, van Langevelde, Huib Jan, additional, van Rossum, Daniel R., additional, Vos, Jesse, additional, Wagner, Jan, additional, Ward-Thompson, Derek, additional, Wardle, John, additional, Washington, Jasmin E., additional, Weintroub, Jonathan, additional, Wharton, Robert, additional, Wiik, Kaj, additional, Witzel, Gunther, additional, Wondrak, Michael F., additional, Wong, George N., additional, Wu 吴, Qingwen 庆文, additional, Yadlapalli, Nitika, additional, Yamaguchi, Paul, additional, Yfantis, Aristomenis, additional, Yoon, Doosoo, additional, Young, André, additional, Young, Ken, additional, Younsi, Ziri, additional, Yu 于, Wei 威, additional, Yuan 袁, Feng 峰, additional, Yuan 袁, Ye-Fei 业飞, additional, Zensus, J. Anton, additional, Zhang, Shuo, additional, Zhao, Guang-Yao, additional, and Zhao 赵, Shan-Shan 杉杉, additional

Published
2023
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27. Reference Array and Design Consideration for the Next-Generation Event Horizon Telescope

Author

Doeleman, Sheperd S., primary, Barrett, John, additional, Blackburn, Lindy, additional, Bouman, Katherine L., additional, Broderick, Avery E., additional, Chaves, Ryan, additional, Fish, Vincent L., additional, Fitzpatrick, Garret, additional, Freeman, Mark, additional, Fuentes, Antonio, additional, Gómez, José L., additional, Haworth, Kari, additional, Houston, Janice, additional, Issaoun, Sara, additional, Johnson, Michael D., additional, Kettenis, Mark, additional, Loinard, Laurent, additional, Nagar, Neil, additional, Narayanan, Gopal, additional, Oppenheimer, Aaron, additional, Palumbo, Daniel C. M., additional, Patel, Nimesh, additional, Pesce, Dominic W., additional, Raymond, Alexander W., additional, Roelofs, Freek, additional, Srinivasan, Ranjani, additional, Tiede, Paul, additional, Weintroub, Jonathan, additional, and Wielgus, Maciek, additional

Published
2023
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28. Spectra of Nearby Galaxies Measured with a New Very Broadband Receiver

Author

Narayanan, Gopal, Snell, Ronald L., Erickson, Neal R., Chung, Aeree, Heyer, Mark H., Yun, Min, and Irvine, William M.

Subjects
Astrophysics
Abstract

Three-millimeter-wavelength spectra of a number of nearby galaxies have been obtained at the Five College Radio Astronomy Observatory (FCRAO) using a new, very broadband receiver. This instrument, which we call the Redshift Search Receiver, has an instantaneous bandwidth of 36 GHz and operates from 74 to 110.5 GHz. The receiver has been built at UMass/FCRAO to be part of the initial instrumentation for the Large Millimeter Telescope (LMT) and is intended primarily for determination of the redshift of distant, dust-obscured galaxies. It is being tested on the FCRAO 14m by measuring the 3mm spectra of a number of nearby galaxies. There are interesting differences in the chemistry of these galaxies., Comment: published in the Proceedings of the International Astronomical Union (2008), 4. Vol 251, pp 251-256 Cambridge University Press

Published
2008
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29. The Five College Radio Astronomy Observatory CO Mapping Survey of the Taurus Molecular Cloud

Author

Narayanan, Gopal, Heyer, Mark H., Brunt, Christopher, Goldsmith, Paul F., Snell, Ronald, and Li, Di

Subjects
Astrophysics
Abstract

The FCRAO Survey of the Taurus Molecular Cloud observed the 12CO and 13CO J=1-0 emission from 98 square degrees of this important, nearby star forming region. This set of data with 45" resolution comprises the highest spatial dynamic range image of an individual molecular cloud constructed to date, and provides valuable insights to the molecular gas distribution, kinematics, and the star formation process. In this contribution, we describe the observations, calibration, data processing, and characteristics of the noise and line emission of the survey. The angular distribution of 12CO and 13CO emission over 1 km/s velocity intervals and the full velocity extent of the cloud are presented. These reveal a complex, dynamic medium of cold, molecular gas., Comment: 35 pages, 22 figures, Accepted for publication in Astrophysical Journal Supplement Series; The figures have been compressed in this version. Full-resolution figures of paper available at http://www.astro.umass.edu/~gopal/taurus-datapaper/

Published
2008
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30. Large-Scale Structure of the Molecular Gas in Taurus Revealed by High Linear Dynamic Range Spectral Line Mapping

Author

Goldsmith, Paul F., Heyer, Mark, Narayanan, Gopal, Snell, Ronald, Li, Di, and Brunt, Chris

Subjects
Astrophysics
Abstract

We report the results of a 100 square degree survey of the Taurus Molecular Cloud region in the J = 1-0 transition of 12CO and 13CO. The image of the cloud in each velocity channel includes ~ 3 million Nyquist sampled pixels on a 20" grid. The high sensitivity and large linear dynamic range of the maps in both isotopologues reveal a very complex, highly structured cloud morphology. There are large scale correlated structures evident in 13CO emission having very fine dimensions, including filaments, cavities, and rings. The 12CO emission shows a quite different structure, with particularly complex interfaces between regions of greater and smaller column density defining the boundaries of the largest-scale cloud structures. The axes of the striations seen in the 12CO emission from relatively diffuse gas are aligned with the direction of the magnetic field. Using a column density-dependent model for the CO fractional abundance, we derive the mass of the region mapped to be 24,000 solar masses, a factor of three greater than would be obtained with canonical CO abundance restricted to the high column density regions. We determine that half the mass of the cloud is in regions having column density below 2.1x10^{21} per square cm. The distribution of young stars in the region covered is highly nonuniform, with the probability of finding a star in a pixel with a specified column density rising sharply for N(H2) = 6x10^{21} cm^{-2}. We determine a relatively low star formation efficiency (mass of young stars/mass of molecular gas), between 0.3 and 1.2 %, and an average star formation rate during the past 3 Myr of 8x10^{-5} stars yr^{-1}., Comment: 53 pages, 21 figures

Published
2008
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31. Discovery Of A Molecular Outflow in the Haro 6-10 Star-Forming Region

Author

Stojimirović, Irena, Narayanan, Gopal, and Snel, Ronald L.

Subjects
Astrophysics
Abstract

We present high sensitivity 12CO and 13CO (1-0) molecular line maps covering the full extent of the parsec scale Haro~6-10 Herbig-Haro (HH) flow. We report the discovery of a molecular CO outflow along the axis of parsec-scale HH flow. Previous molecular studies missed the identification of the outflow probably due to their smaller mapping area and the confusing spectral features present towards the object. Our detailed molecular line study of the full 1.6 pc extent of the optical flow shows evidence for both blueshifted and redshifted gas set in motion by Haro~6-10 activity. The molecular outflow is centered at Haro~6-10, with redshifted gas being clumpy and directed towards the northeast, while blueshifted gas is in the southwest direction. The molecular gas terminates well within the cloud, short of the most distant HH objects of the optical flow. Contamination from an unrelated cloud along the same line of sight prevents a thorough study of the blueshifted outflow lobe and the mass distribution at the lowest velocities in both lobes. The cloud core in which Haro~6-10 is embedded is filamentary and flattened in the east-west direction. The total cloud mass is calculated from 13CO(1-0) to be ~200Msun. The lower limit of the mass associated with the outflow is ~0.25Msun., Comment: ApJ Accepted; 9 pages, 8 figures. For high resolution ps file use: http://www.astro.umass.edu/~irena/haro.ps

Published
2007
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33. Entrainment Mechanisms for Outflows in the L1551 Star-Forming Region

Author

Stojimirović, Irena, Narayanan, Gopal, Snell, Ronald L., and Bally, John

Subjects
Astrophysics
Abstract

We present high sensitivity 12/13CO(1-0) molecular line maps covering the full extent of the parsec scale L1551 molecular outflow, including the redshifted east-west (EW) flow. We also present 12CO(3-2) data that extends over a good fraction of the area mapped in the 1-0 transition. We compare the molecular data to widefield, narrow-band optical emission in H$\alpha$. While there are multiple outflows in the L1551 cloud, the main outflow is oriented at 50\arcdeg position angle and appears to be driven by embedded source(s) in the central IRS 5 region. The 3-2 data indicate that there may be molecular emission associated with the L1551 NE jet, within the redshifted lobe of main outflow. We have also better defined the previously known EW flow and believe we have identified its blueshifted counterpart. We further speculate that the origin of the EW outflow lies near HH 102. We use velocity dependent opacity correction to estimate the mass and the energy of the outflow. The resulting mass spectral indices from our analysis, are systematically lower (less steep) than the power law indices obtained towards other outflows in several recent studies that use a similar opacity correction method. We show that systematic errors and biases in the analysis procedures for deriving mass spectra could result in errors in the determination of the power-law indices. The mass spectral indices, the morphological appearance of the position-velocity plots and integrated intensity emission maps of the molecular data, compared with the optical, suggest that jet-driven bow-shock entrainment is the best explanation for the driving mechanism of outflows in L1551. The kinetic energy of the outflows is found to be comparable to the binding energy of the cloud and sufficient to maintain the turbulence in the L1551 cloud., Comment: Accepted for publication in The Astrophysical Journal, 20 September 2006 (vol. 649n 1 issue). 33 pages plus 17 Figures. For a paper with high resolution figures go to http://www.astro.umass.edu/~irena/ms.ps.gz

Published
2006
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34. SuperCam, a 64-pixel heterodyne imaging array for the 870 micron atmospheric window

Author

Groppi, Christopher, Walker, Christopher, Kulesa, Craig, Puetz, Patrick, Golish, Dathon, Gensheimer, Paul, Hedden, Abigail, Bussmann, Shane, Weinreb, Sander, Kuiper, Thomas, Kooi, Jacob, Jones, Glenn, Bardin, Joseph, Mani, Hamdi, Lichtenberger, Arthur, and Narayanan, Gopal

Subjects
Astrophysics
Abstract

We report on the development of SuperCam, a 64 pixel, superheterodyne camera designed for operation in the astrophysically important 870 micron atmospheric window. SuperCam will be used to answer fundamental questions about the physics and chemistry of molecular clouds in the Galaxy and their direct relation to star and planet formation. The advent of such a system will provide an order of magnitude increase in mapping speed over what is now available and revolutionize how observational astronomy is performed in this important wavelength regime. Unlike the situation with bolometric detectors, heterodyne receiver systems are coherent, retaining information about both the amplitude and phase of the incident photon stream. From this information a high resolution spectrum of the incident light can be obtained without multiplexing. SuperCam will be constructed by stacking eight, 1x8 rows of fixed tuned, SIS mixers. The IF output of each mixer will be connected to a low-noise, broadband MMIC amplifier integrated into the mixer block. The instantaneous IF bandwidth of each pixel will be ~2 GHz, with a center frequency of 5 GHz. A spectrum of the central 500 MHz of each IF band will be provided by the array spectrometer. Local oscillator power is provided by a frequency multiplier whose output is divided between the pixels by using a matrix of waveguide power dividers. The mixer array will be cooled to 4K by a closed-cycle refrigeration system. SuperCam will reside at the Cassegrain focus of the 10m Heinrich Hertz telescope (HHT). A prototype single row of the array will be tested on the HHT in 2006, with the first engineering run of the full array in late 2007. The array is designed and constructed so that it may be readily scaled to higher frequencies., Comment: 12 pages, 14 figures, to be published in the Proceedings of SPIE Vol. 6275, "Astronomical Telescopes and Instrumentation, Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III"

Published
2006
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35. Kinematics of Protostellar Objects in the $\rho$ Ophiuchus A Region

Author

Narayanan, Gopal and Logan, Daniel W.

Subjects
Astrophysics
Abstract

We present the detection of infall, rotation and outflow kinematic signatures towards both a protostellar source, VLA 1623 and what was initially thought to be a pre-protostellar core, SM1N, in the rho-Ophiuchus A region. The kinematic signatures of early star formation were detected in the dense molecular gas surrounding the embedded sources using high signal-to-noise millimeter and submillimeter data. Centroid velocity maps made with HCO+ J=4->3 and J=1->0 line emission exhibit the blue bulge signature of infall, which is predicted to be seen when infall motion dominates over rotational motion. Further evidence for infalling gas is found in the HCO+ blue asymmetric line profiles and red asymmetric opacity profiles. We also performed CO J=3->2 and J=1->0 observations to determine the direction, orientation, and extent of molecular outflows, and report the discovery of a new bipolar outflow possibly driven by SM1N., Comment: 8 pages, 7 figures, accepted for publication in the Astrophysical Journal

Published
2006
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36. Star Formation in Bright Rimmed Clouds. I. Millimeter and Submillimeter Molecular Line Surveys

Author

De Vries, Christopher H., Narayanan, Gopal, and Snell, Ronald L.

Subjects
Astrophysics
Abstract

We present the results of the first detailed millimeter and submillimeter molecular line survey of bright rimmed clouds, observed at FCRAO in the CO (J=1-0), C18O (J=1-0), HCO+ (J=1-0), H13CO+ (J=1-0), and N2H+ (J=1-0) transitions, and at the HHT in the CO (J=2-1), HCO+ (J=3-2), HCO+ (J=4-3), H13CO+ (J=3-2), and H13CO+ (J=4-3) molecular line transitions. The source list is composed of a selection of bright rimmed clouds from the catalog of such objects compiled by Sugitani et al. (1991). We also present observations of three Bok globules done for comparison with the bright rimmed clouds. We find that the appearance of the millimeter CO and HCO+ emission is dominated by the morphology of the shock front in the bright rimmed clouds. The HCO+ (J=1-0) emission tends to trace the swept up gas ridge and overdense regions which may be triggered to collapse as a result of sequential star formation. Five of the seven bright rimmed clouds we observe seem to have an outflow, however only one shows the spectral line blue-asymmetric signature that is indicative of infall, in the optically thick HCO+ emission. We also present evidence that in bright rimmed clouds the nearby shock front may heat the core from outside-in thereby washing out the normally observed line infall signatures seen in isolated star forming regions. We find that the derived core masses of these bright rimmed clouds are similar to other low and intermediate mass star forming regions., Comment: 67 pages, including 35 figures and 6 tables. Accepted for publication in ApJ. Version with embedded full-resolution figures available at http://www.astro.umass.edu/~devries/brc1/

Published
2002
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37. Star Formation, Observations

Author

Narayanan, Gopal, Gargaud, Muriel, editor, Irvine, William M., editor, Amils, Ricardo, editor, Cleaves, Henderson James (Jim), II, editor, Pinti, Daniele L., editor, Quintanilla, José Cernicharo, editor, Rouan, Daniel, editor, Spohn, Tilman, editor, Tirard, Stéphane, editor, and Viso, Michel, editor

Published
2015
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38. A dusty star-forming galaxy at z = 6 revealed by strong gravitational lensing

Author

Zavala, Jorge A., Montaña, Alfredo, Hughes, David H., Yun, Min S., Ivison, R. J., Valiante, Elisabetta, Wilner, David, Spilker, Justin, Aretxaga, Itziar, Eales, Stephen, Avila-Reese, Vladimir, Chávez, Miguel, Cooray, Asantha, Dannerbauer, Helmut, Dunlop, James S., Dunne, Loretta, Gómez-Ruiz, Arturo I., Michałowski, Michał J., Narayanan, Gopal, Nayyeri, Hooshang, Oteo, Ivan, Rosa González, Daniel, Sánchez-Argüelles, David, Schloerb, F. Peter, Serjeant, Stephen, Smith, Matthew W. L., Terlevich, Elena, Vega, Olga, Villalba, Alan, van der Werf, Paul, Wilson, Grant W., and Zeballos, Milagros

Published
2018
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39. Comparison of Polarized Radiative Transfer Codes Used by the EHT Collaboration

Author

Prather, Ben S., primary, Dexter, Jason, additional, Moscibrodzka, Monika, additional, Pu, Hung-Yi, additional, Bronzwaer, Thomas, additional, Davelaar, Jordy, additional, Younsi, Ziri, additional, Gammie, Charles F., additional, Gold, Roman, additional, Wong, George N., additional, Akiyama, Kazunori, additional, Alberdi, Antxon, additional, Alef, Walter, additional, Algaba, Juan Carlos, additional, Anantua, Richard, additional, Asada, Keiichi, additional, Azulay, Rebecca, additional, Bach, Uwe, additional, Baczko, Anne-Kathrin, additional, Ball, David, additional, Baloković, Mislav, additional, Barrett, John, additional, Bauböck, Michi, additional, Benson, Bradford A., additional, Bintley, Dan, additional, Blackburn, Lindy, additional, Blundell, Raymond, additional, Bouman, Katherine L., additional, Bower, Geoffrey C., additional, Boyce, Hope, additional, Bremer, Michael, additional, Brinkerink, Christiaan D., additional, Brissenden, Roger, additional, Britzen, Silke, additional, Broderick, Avery E., additional, Broguiere, Dominique, additional, Bustamante, Sandra, additional, Byun, Do-Young, additional, Carlstrom, John E., additional, Ceccobello, Chiara, additional, Chael, Andrew, additional, Chan, Chi-kwan, additional, Chang, Dominic O., additional, Chatterjee, Koushik, additional, Chatterjee, Shami, additional, Chen, Ming-Tang, additional, Chen, Yongjun, additional, Cheng, Xiaopeng, additional, Cho, Ilje, additional, Christian, Pierre, additional, Conroy, Nicholas S., additional, Conway, John E., additional, Cordes, James M., additional, Crawford, Thomas M., additional, Crew, Geoffrey B., additional, Cruz-Osorio, Alejandro, additional, Cui, Yuzhu, additional, De Laurentis, Mariafelicia, additional, Deane, Roger, additional, Dempsey, Jessica, additional, Desvignes, Gregory, additional, Dhruv, Vedant, additional, Doeleman, Sheperd S., additional, Dougal, Sean, additional, Dzib, Sergio A., additional, Eatough, Ralph P., additional, Emami, Razieh, additional, Falcke, Heino, additional, Farah, Joseph, additional, Fish, Vincent L., additional, Fomalont, Ed, additional, Ford, H. Alyson, additional, Fraga-Encinas, Raquel, additional, Freeman, William T., additional, Friberg, Per, additional, Fromm, Christian M., additional, Fuentes, Antonio, additional, Galison, Peter, additional, García, Roberto, additional, Gentaz, Olivier, additional, Georgiev, Boris, additional, Goddi, Ciriaco, additional, Gómez-Ruiz, Arturo I., additional, Gómez, José L., additional, Gu, Minfeng, additional, Gurwell, Mark, additional, Hada, Kazuhiro, additional, Haggard, Daryl, additional, Haworth, Kari, additional, Hecht, Michael H., additional, Hesper, Ronald, additional, Heumann, Dirk, additional, Ho, Luis C., additional, Ho, Paul, additional, Honma, Mareki, additional, Huang, Chih-Wei L., additional, Huang, Lei, additional, Hughes, David H., additional, Ikeda, Shiro, additional, Impellizzeri, C. M. Violette, additional, Inoue, Makoto, additional, Issaoun, Sara, additional, James, David J., additional, Jannuzi, Buell T., additional, Janssen, Michael, additional, Jeter, Britton, additional, Jiang, Wu, additional, Jiménez-Rosales, Alejandra, additional, Johnson, Michael D., additional, Jorstad, Svetlana, additional, Joshi, Abhishek V., additional, Jung, Taehyun, additional, Karami, Mansour, additional, Karuppusamy, Ramesh, additional, Kawashima, Tomohisa, additional, Keating, Garrett K., additional, Kettenis, Mark, additional, Kim, Dong-Jin, additional, Kim, Jae-Young, additional, Kim, Jongsoo, additional, Kim, Junhan, additional, Kino, Motoki, additional, Koay, Jun Yi, additional, Kocherlakota, Prashant, additional, Kofuji, Yutaro, additional, Koyama, Shoko, additional, Kramer, Carsten, additional, Kramer, Michael, additional, Krichbaum, Thomas P., additional, Kuo, Cheng-Yu, additional, La Bella, Noemi, additional, Lauer, Tod R., additional, Lee, Daeyoung, additional, Lee, Sang-Sung, additional, Leung, Po Kin, additional, Levis, Aviad, additional, Li, Zhiyuan, additional, Lico, Rocco, additional, Lindahl, Greg, additional, Lindqvist, Michael, additional, Lisakov, Mikhail, additional, Liu, Jun, additional, Liu, Kuo, additional, Liuzzo, Elisabetta, additional, Lo, Wen-Ping, additional, Lobanov, Andrei P., additional, Loinard, Laurent, additional, Lonsdale, Colin J., additional, Lu, Ru-Sen, additional, MacDonald, Nicholas R., additional, Mao, Jirong, additional, Marchili, Nicola, additional, Markoff, Sera, additional, Marrone, Daniel P., additional, Marscher, Alan P., additional, Martí-Vidal, Iván, additional, Matsushita, Satoki, additional, Matthews, Lynn D., additional, Medeiros, Lia, additional, Menten, Karl M., additional, Michalik, Daniel, additional, Mizuno, Izumi, additional, Mizuno, Yosuke, additional, Moran, James M., additional, Moriyama, Kotaro, additional, Müller, Cornelia, additional, Mus, Alejandro, additional, Musoke, Gibwa, additional, Myserlis, Ioannis, additional, Nadolski, Andrew, additional, Nagai, Hiroshi, additional, Nagar, Neil M., additional, Nakamura, Masanori, additional, Narayan, Ramesh, additional, Narayanan, Gopal, additional, Natarajan, Iniyan, additional, Nathanail, Antonios, additional, Fuentes, Santiago Navarro, additional, Neilsen, Joey, additional, Neri, Roberto, additional, Ni, Chunchong, additional, Noutsos, Aristeidis, additional, Nowak, Michael A., additional, Oh, Junghwan, additional, Okino, Hiroki, additional, Olivares, Héctor, additional, Ortiz-León, Gisela N., additional, Oyama, Tomoaki, additional, Özel, Feryal, additional, Palumbo, Daniel C. M., additional, Paraschos, Georgios Filippos, additional, Park, Jongho, additional, Parsons, Harriet, additional, Patel, Nimesh, additional, Pen, Ue-Li, additional, Pesce, Dominic W., additional, Piétu, Vincent, additional, Plambeck, Richard, additional, PopStefanija, Aleksandar, additional, Porth, Oliver, additional, Pötzl, Felix M., additional, Preciado-López, Jorge A., additional, Psaltis, Dimitrios, additional, Ramakrishnan, Venkatessh, additional, Rao, Ramprasad, additional, Rawlings, Mark G., additional, Raymond, Alexander W., additional, Rezzolla, Luciano, additional, Ricarte, Angelo, additional, Ripperda, Bart, additional, Roelofs, Freek, additional, Rogers, Alan, additional, Ros, Eduardo, additional, Romero-Cañizales, Cristina, additional, Roshanineshat, Arash, additional, Rottmann, Helge, additional, Roy, Alan L., additional, Ruiz, Ignacio, additional, Ruszczyk, Chet, additional, Rygl, Kazi L. J., additional, Sánchez, Salvador, additional, Sánchez-Argüelles, David, additional, Sánchez-Portal, Miguel, additional, Sasada, Mahito, additional, Satapathy, Kaushik, additional, Savolainen, Tuomas, additional, Schloerb, F. Peter, additional, Schonfeld, Jonathan, additional, Schuster, Karl-Friedrich, additional, Shao, Lijing, additional, Shen, Zhiqiang, additional, Small, Des, additional, Sohn, Bong Won, additional, SooHoo, Jason, additional, Souccar, Kamal, additional, Sun, He, additional, Tazaki, Fumie, additional, Tetarenko, Alexandra J., additional, Tiede, Paul, additional, Tilanus, Remo P. J., additional, Titus, Michael, additional, Torne, Pablo, additional, Traianou, Efthalia, additional, Trent, Tyler, additional, Trippe, Sascha, additional, Turk, Matthew, additional, van Bemmel, Ilse, additional, van Langevelde, Huib Jan, additional, van Rossum, Daniel R., additional, Vos, Jesse, additional, Wagner, Jan, additional, Ward-Thompson, Derek, additional, Wardle, John, additional, Weintroub, Jonathan, additional, Wex, Norbert, additional, Wharton, Robert, additional, Wielgus, Maciek, additional, Wiik, Kaj, additional, Witzel, Gunther, additional, Wondrak, Michael F., additional, Wu, Qingwen, additional, Yamaguchi, Paul, additional, Yfantis, Aristomenis, additional, Yoon, Doosoo, additional, Young, André, additional, Young, Ken, additional, Yu, Wei, additional, Yuan, Feng, additional, Yuan, Ye-Fei, additional, Zensus, J. Anton, additional, Zhang, Shuo, additional, Zhao, Guang-Yao, additional, and Zhao, Shan-Shan, additional

Published
2023
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40. Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes

Author

Roelofs, Freek, Johnson, Michael D., Chael, Andrew, Janssen, Michael, Wielgus, Maciek, Broderick, Avery E., Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Bach, Uwe, Baczko, Anne-Kathrin, Ball, David, Baloković, Mislav, Barrett, John, Bauböck, Michi, Benson, Bradford A., Bintley, Dan, Blackburn, Lindy, Blundell, Raymond, Bouman, Katherine L., Bower, Geoffrey C., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broguiere, Dominique, Bronzwaer, Thomas, Bustamante, Sandra, Byun, Do-Young, Carlstrom, John E., Ceccobello, Chiara, Chan, Chi-kwan, Chang, Dominic O., Chatterjee, Koushik, Chatterjee, Shami, Chen, Ming-Tang, Chen, Yongjun, Cheng, Xiaopeng, Cho, Ilje, Christian, Pierre, Conroy, Nicholas S., Conway, John E., Cordes, James M., Crawford, Thomas M., Crew, Geoffrey B., Cruz-Osorio, Alejandro, Cui, Yuzhu, Dahale, Rohan, Davelaar, Jordy, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Dexter, Jason, Dhruv, Vedant, Doeleman, Sheperd S., Dougal, Sean, Dzib, Sergio A., Eatough, Ralph P., Emami, Razieh, Falcke, Heino, Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Ford, H. Alyson, Foschi, Marianna, Fraga-Encinas, Raquel, Freeman, William T., Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, Gammie, Charles F., García, Roberto, Gentaz, Olivier, Georgiev, Boris, Goddi, Ciriaco, Gold, Roman, Gómez-Ruiz, Arturo I., Gómez, José L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Haworth, Kari, Hecht, Michael H., Hesper, Ronald, Heumann, Dirk, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Impellizzeri, C. M. Violette, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Jeter, Britton, Jiang, Wu, Jiménez-Rosales, Alejandra, Jorstad, Svetlana, Joshi, Abhishek V., Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kocherlakota, Prashant, Kofuji, Yutaro, Koch, Patrick M., Koyama, Shoko, Kramer, Carsten, Kramer, Joana A., Kramer, Michael, Krichbaum, Thomas P., Kuo, Cheng-Yu, La Bella, Noemi, Lauer, Tod R., Lee, Daeyoung, Lee, Sang-Sung, Leung, Po Kin, Levis, Aviad, Li, Zhiyuan, Lico, Rocco, Lindahl, Greg, Lindqvist, Michael, Lisakov, Mikhail, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lo, Wen-Ping, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin J., Lowitz, Amy E., Lu, Ru-Sen, MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Martí-Vidal, Iván, Matsushita, Satoki, Matthews, Lynn D., Medeiros, Lia, Menten, Karl M., Michalik, Daniel, Mizuno, Izumi, Mizuno, Yosuke, Moran, James M., Moriyama, Kotaro, Moscibrodzka, Monika, Mulaudzi, Wanga, Müller, Cornelia, Müller, Hendrik, Mus, Alejandro, Musoke, Gibwa, Myserlis, Ioannis, Nadolski, Andrew, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Fuentes, Santiago Navarro, Neilsen, Joey, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Oh, Junghwan, Okino, Hiroki, Olivares, Héctor, Ortiz-León, Gisela N., Oyama, Tomoaki, Özel, Feryal, Palumbo, Daniel C. M., Paraschos, Georgios Filippos, Park, Jongho, Parsons, Harriet, Patel, Nimesh, Pen, Ue-Li, Pesce, Dominic W., Piétu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Pötzl, Felix M., Prather, Ben, Preciado-López, Jorge A., Psaltis, Dimitrios, Pu, Hung-Yi, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Raymond, Alexander W., Rezzolla, Luciano, Ricarte, Angelo, Ripperda, Bart, Rogers, Alan, Romero-Cañizales, Cristina, Ros, Eduardo, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruiz, Ignacio, Ruszczyk, Chet, Rygl, Kazi L. J., Sánchez, Salvador, Sánchez-Argüelles, David, Sánchez-Portal, Miguel, Sasada, Mahito, Satapathy, Kaushik, Savolainen, Tuomas, Schloerb, F. Peter, Schonfeld, Jonathan, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Sosapanta Salas, León David, Souccar, Kamal, Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Torne, Pablo, Toscano, Teresa, Traianou, Efthalia, Trent, Tyler, Trippe, Sascha, Turk, Matthew, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Vos, Jesse, Wagner, Jan, Ward-Thompson, Derek, Wardle, John, Washington, Jasmin E., Weintroub, Jonathan, Wharton, Robert, Wiik, Kaj, Witzel, Gunther, Wondrak, Michael F., Wong, George N., Wu, Qingwen, Yadlapalli, Nitika, Yamaguchi, Paul, Yfantis, Aristomenis, Yoon, Doosoo, Young, André, Young, Ken, Younsi, Ziri, Yu, Wei, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhang, Shuo, Zhao, Guang-Yao, Zhao, Shan-Shan, Roelofs, Freek, Johnson, Michael D., Chael, Andrew, Janssen, Michael, Wielgus, Maciek, Broderick, Avery E., Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Bach, Uwe, Baczko, Anne-Kathrin, Ball, David, Baloković, Mislav, Barrett, John, Bauböck, Michi, Benson, Bradford A., Bintley, Dan, Blackburn, Lindy, Blundell, Raymond, Bouman, Katherine L., Bower, Geoffrey C., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broguiere, Dominique, Bronzwaer, Thomas, Bustamante, Sandra, Byun, Do-Young, Carlstrom, John E., Ceccobello, Chiara, Chan, Chi-kwan, Chang, Dominic O., Chatterjee, Koushik, Chatterjee, Shami, Chen, Ming-Tang, Chen, Yongjun, Cheng, Xiaopeng, Cho, Ilje, Christian, Pierre, Conroy, Nicholas S., Conway, John E., Cordes, James M., Crawford, Thomas M., Crew, Geoffrey B., Cruz-Osorio, Alejandro, Cui, Yuzhu, Dahale, Rohan, Davelaar, Jordy, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Dexter, Jason, Dhruv, Vedant, Doeleman, Sheperd S., Dougal, Sean, Dzib, Sergio A., Eatough, Ralph P., Emami, Razieh, Falcke, Heino, Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Ford, H. Alyson, Foschi, Marianna, Fraga-Encinas, Raquel, Freeman, William T., Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, Gammie, Charles F., García, Roberto, Gentaz, Olivier, Georgiev, Boris, Goddi, Ciriaco, Gold, Roman, Gómez-Ruiz, Arturo I., Gómez, José L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Haworth, Kari, Hecht, Michael H., Hesper, Ronald, Heumann, Dirk, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Impellizzeri, C. M. Violette, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Jeter, Britton, Jiang, Wu, Jiménez-Rosales, Alejandra, Jorstad, Svetlana, Joshi, Abhishek V., Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kocherlakota, Prashant, Kofuji, Yutaro, Koch, Patrick M., Koyama, Shoko, Kramer, Carsten, Kramer, Joana A., Kramer, Michael, Krichbaum, Thomas P., Kuo, Cheng-Yu, La Bella, Noemi, Lauer, Tod R., Lee, Daeyoung, Lee, Sang-Sung, Leung, Po Kin, Levis, Aviad, Li, Zhiyuan, Lico, Rocco, Lindahl, Greg, Lindqvist, Michael, Lisakov, Mikhail, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lo, Wen-Ping, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin J., Lowitz, Amy E., Lu, Ru-Sen, MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Martí-Vidal, Iván, Matsushita, Satoki, Matthews, Lynn D., Medeiros, Lia, Menten, Karl M., Michalik, Daniel, Mizuno, Izumi, Mizuno, Yosuke, Moran, James M., Moriyama, Kotaro, Moscibrodzka, Monika, Mulaudzi, Wanga, Müller, Cornelia, Müller, Hendrik, Mus, Alejandro, Musoke, Gibwa, Myserlis, Ioannis, Nadolski, Andrew, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Fuentes, Santiago Navarro, Neilsen, Joey, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Oh, Junghwan, Okino, Hiroki, Olivares, Héctor, Ortiz-León, Gisela N., Oyama, Tomoaki, Özel, Feryal, Palumbo, Daniel C. M., Paraschos, Georgios Filippos, Park, Jongho, Parsons, Harriet, Patel, Nimesh, Pen, Ue-Li, Pesce, Dominic W., Piétu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Pötzl, Felix M., Prather, Ben, Preciado-López, Jorge A., Psaltis, Dimitrios, Pu, Hung-Yi, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Raymond, Alexander W., Rezzolla, Luciano, Ricarte, Angelo, Ripperda, Bart, Rogers, Alan, Romero-Cañizales, Cristina, Ros, Eduardo, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruiz, Ignacio, Ruszczyk, Chet, Rygl, Kazi L. J., Sánchez, Salvador, Sánchez-Argüelles, David, Sánchez-Portal, Miguel, Sasada, Mahito, Satapathy, Kaushik, Savolainen, Tuomas, Schloerb, F. Peter, Schonfeld, Jonathan, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Sosapanta Salas, León David, Souccar, Kamal, Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Torne, Pablo, Toscano, Teresa, Traianou, Efthalia, Trent, Tyler, Trippe, Sascha, Turk, Matthew, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Vos, Jesse, Wagner, Jan, Ward-Thompson, Derek, Wardle, John, Washington, Jasmin E., Weintroub, Jonathan, Wharton, Robert, Wiik, Kaj, Witzel, Gunther, Wondrak, Michael F., Wong, George N., Wu, Qingwen, Yadlapalli, Nitika, Yamaguchi, Paul, Yfantis, Aristomenis, Yoon, Doosoo, Young, André, Young, Ken, Younsi, Ziri, Yu, Wei, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhang, Shuo, Zhao, Guang-Yao, and Zhao, Shan-Shan

Abstract

The Event Horizon Telescope (EHT) is a millimeter very long baseline interferometry (VLBI) array that has imaged the apparent shadows of the supermassive black holes M87* and Sagittarius A*. Polarimetric data from these observations contain a wealth of information on the black hole and accretion flow properties. In this work, we develop polarimetric geometric modeling methods for mm-VLBI data, focusing on approaches that fit data products with differing degrees of invariance to broad classes of calibration errors. We establish a fitting procedure using a polarimetric “m-ring” model to approximate the image structure near a black hole. By fitting this model to synthetic EHT data from general relativistic magnetohydrodynamic models, we show that the linear and circular polarization structure can be successfully approximated with relatively few model parameters. We then fit this model to EHT observations of M87* taken in 2017. In total intensity and linear polarization, the m-ring fits are consistent with previous results from imaging methods. In circular polarization, the m-ring fits indicate the presence of event-horizon-scale circular polarization structure, with a persistent dipolar asymmetry and orientation across several days. The same structure was recovered independently of observing band, used data products, and model assumptions. Despite this broad agreement, imaging methods do not produce similarly consistent results. Our circular polarization results, which imposed additional assumptions on the source structure, should thus be interpreted with some caution. Polarimetric geometric modeling provides a useful and powerful method to constrain the properties of horizon-scale polarized emission, particularly for sparse arrays like the EHT.

Published
2023

41. Reference Array and Design Consideration for the Next-Generation Event Horizon Telescope

Author

Haystack Observatory, Doeleman, Sheperd S., Barrett, John, Blackburn, Lindy, Bouman, Katherine L., Broderick, Avery E., Chaves, Ryan, Fish, Vincent L., Fitzpatrick, Garret, Freeman, Mark, Fuentes, Antonio, Gómez, José L., Haworth, Kari, Houston, Janice, Issaoun, Sara, Johnson, Michael D., Kettenis, Mark, Loinard, Laurent, Nagar, Neil, Narayanan, Gopal, Oppenheimer, Aaron, Haystack Observatory, Doeleman, Sheperd S., Barrett, John, Blackburn, Lindy, Bouman, Katherine L., Broderick, Avery E., Chaves, Ryan, Fish, Vincent L., Fitzpatrick, Garret, Freeman, Mark, Fuentes, Antonio, Gómez, José L., Haworth, Kari, Houston, Janice, Issaoun, Sara, Johnson, Michael D., Kettenis, Mark, Loinard, Laurent, Nagar, Neil, Narayanan, Gopal, and Oppenheimer, Aaron

Abstract

We describe the process to design, architect, and implement a transformative enhancement of the Event Horizon Telescope (EHT). This program—the next-generation Event Horizon Telescope (ngEHT)—will form a networked global array of radio dishes capable of making high-fidelity real-time movies of supermassive black holes (SMBH) and their emanating jets. This builds upon the EHT principally by deploying additional modest-diameter dishes to optimized geographic locations to enhance the current global mm/submm wavelength Very Long Baseline Interferometric (VLBI) array, which has, to date, utilized mostly pre-existing radio telescopes. The ngEHT program further focuses on observing at three frequencies simultaneously for increased sensitivity and Fourier spatial frequency coverage. Here, the concept, science goals, design considerations, station siting, and instrument prototyping are discussed, and a preliminary reference array to be implemented in phases is described.

Published
2023

42. Reference Array and Design Consideration for the Next-Generation Event Horizon Telescope

Author

National Science Foundation (US), Gordon and Betty Moore Foundation, Consejo Nacional de Ciencia y Tecnología (México), Universidad Nacional Autónoma de México, Harvard University, John Templeton Foundation, Agencia Nacional de Investigación y Desarrollo (Chile), Fondo Nacional de Desarrollo Científico y Tecnológico (Chile), Doeleman, Sheperd S., Barrett, John, Blackburn, Lindy, Bouman, Katherine L., Broderick, Avery E., Chaves, Ryan, Fish, Vincent L., Fitzpatrick, Garret, Freeman, Mark, Fuentes, Antonio, Gómez, José L., Haworth, Kari, Houston, Janice, Issaoun, Sara, Johnson, Michael D., Kettenis, Mark, Loinard, Laurent, Nagar, Neil M., Narayanan, Gopal, Oppenheimer, Aaron, Palumbo, Daniel C. M., Patel, Nimesh, Pesce, Dominic W., Raymond, Alexander W., Roelofs, Freek, Srinivasan, Ranjani, Tiede, Paul, Weintroub, Jonathan, Wielgus, Maciek, National Science Foundation (US), Gordon and Betty Moore Foundation, Consejo Nacional de Ciencia y Tecnología (México), Universidad Nacional Autónoma de México, Harvard University, John Templeton Foundation, Agencia Nacional de Investigación y Desarrollo (Chile), Fondo Nacional de Desarrollo Científico y Tecnológico (Chile), Doeleman, Sheperd S., Barrett, John, Blackburn, Lindy, Bouman, Katherine L., Broderick, Avery E., Chaves, Ryan, Fish, Vincent L., Fitzpatrick, Garret, Freeman, Mark, Fuentes, Antonio, Gómez, José L., Haworth, Kari, Houston, Janice, Issaoun, Sara, Johnson, Michael D., Kettenis, Mark, Loinard, Laurent, Nagar, Neil M., Narayanan, Gopal, Oppenheimer, Aaron, Palumbo, Daniel C. M., Patel, Nimesh, Pesce, Dominic W., Raymond, Alexander W., Roelofs, Freek, Srinivasan, Ranjani, Tiede, Paul, Weintroub, Jonathan, and Wielgus, Maciek

Abstract

We describe the process to design, architect, and implement a transformative enhancement of the Event Horizon Telescope (EHT). This program—the next-generation Event Horizon Telescope (ngEHT)—will form a networked global array of radio dishes capable of making high-fidelity real-time movies of supermassive black holes (SMBH) and their emanating jets. This builds upon the EHT principally by deploying additional modest-diameter dishes to optimized geographic locations to enhance the current global mm/submm wavelength Very Long Baseline Interferometric (VLBI) array, which has, to date, utilized mostly pre-existing radio telescopes. The ngEHT program further focuses on observing at three frequencies simultaneously for increased sensitivity and Fourier spatial frequency coverage. Here, the concept, science goals, design considerations, station siting, and instrument prototyping are discussed, and a preliminary reference array to be implemented in phases is described.

Published
2023

43. Enabling Transformational ngEHT Science via the Inclusion of 86 GHz Capabilities

Author

Haystack Observatory, Issaoun, Sara, Pesce, Dominic W., Roelofs, Freek, Chael, Andrew, Dodson, Richard, Rioja, María J., Akiyama, Kazunori, Aran, Romy, Blackburn, Lindy, Doeleman, Sheperd S., Fish, Vincent L., Fitzpatrick, Garret, Johnson, Michael D., Narayanan, Gopal, Raymond, Alexander W., Tilanus, Remo P. J., Haystack Observatory, Issaoun, Sara, Pesce, Dominic W., Roelofs, Freek, Chael, Andrew, Dodson, Richard, Rioja, María J., Akiyama, Kazunori, Aran, Romy, Blackburn, Lindy, Doeleman, Sheperd S., Fish, Vincent L., Fitzpatrick, Garret, Johnson, Michael D., Narayanan, Gopal, Raymond, Alexander W., and Tilanus, Remo P. J.

Abstract

We present a case for significantly enhancing the utility and efficiency of the ngEHT by incorporating an additional 86 GHz observing band. In contrast to 230 or 345 GHz, weather conditions at the ngEHT sites are reliably good enough for 86 GHz to enable year-round observations. Multi-frequency imaging that incorporates 86 GHz observations would sufficiently augment the (u,v)emantics> coverage at 230 and 345 GHz to permit detection of the M87 jet structure without requiring EHT stations to join the array. The general calibration and sensitivity of the ngEHT would also be enhanced by leveraging frequency phase transfer techniques, whereby simultaneous observations at 86 GHz and higher-frequency bands have the potential to increase the effective coherence times from a few seconds to tens of minutes. When observation at the higher frequencies is not possible, there are opportunities for standalone 86 GHz science, such as studies of black hole jets and spectral lines. Finally, the addition of 86 GHz capabilities to the ngEHT would enable it to integrate into a community of other VLBI facilities—such as the GMVA and ngVLA—that are expected to operate at 86 GHz but not at the higher ngEHT observing frequencies.

Published
2023

44. Enabling Transformational ngEHT Science via the Inclusion of 86 GHz Capabilities

Author

Issaoun, Sara, primary, Pesce, Dominic W., additional, Roelofs, Freek, additional, Chael, Andrew, additional, Dodson, Richard, additional, Rioja, María J., additional, Akiyama, Kazunori, additional, Aran, Romy, additional, Blackburn, Lindy, additional, Doeleman, Sheperd S., additional, Fish, Vincent L., additional, Fitzpatrick, Garret, additional, Johnson, Michael D., additional, Narayanan, Gopal, additional, Raymond, Alexander W., additional, and Tilanus, Remo P. J., additional

Published
2023
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45. The Event Horizon Telescope Image of the Quasar NRAO 530

Author

Jorstad, Svetlana, primary, Wielgus, Maciek, additional, Lico, Rocco, additional, Issaoun, Sara, additional, Broderick, Avery E., additional, Pesce, Dominic W., additional, Liu, Jun, additional, Zhao, Guang-Yao, additional, Krichbaum, Thomas P., additional, Blackburn, Lindy, additional, Chan, Chi-kwan, additional, Janssen, Michael, additional, Ramakrishnan, Venkatessh, additional, Akiyama, Kazunori, additional, Alberdi, Antxon, additional, Algaba, Juan Carlos, additional, Bouman, Katherine L., additional, Cho, Ilje, additional, Fuentes, Antonio, additional, Gómez, José L., additional, Gurwell, Mark, additional, Johnson, Michael D., additional, Kim, Jae-Young, additional, Lu, Ru-Sen, additional, Martí-Vidal, Iván, additional, Moscibrodzka, Monika, additional, Pötzl, Felix M., additional, Traianou, Efthalia, additional, van Bemmel, Ilse, additional, Alef, Walter, additional, Anantua, Richard, additional, Asada, Keiichi, additional, Azulay, Rebecca, additional, Bach, Uwe, additional, Baczko, Anne-Kathrin, additional, Ball, David, additional, Baloković, Mislav, additional, Barrett, John, additional, Bauböck, Michi, additional, Benson, Bradford A., additional, Bintley, Dan, additional, Blundell, Raymond, additional, Bower, Geoffrey C., additional, Boyce, Hope, additional, Bremer, Michael, additional, Brinkerink, Christiaan D., additional, Brissenden, Roger, additional, Britzen, Silke, additional, Broguiere, Dominique, additional, Bronzwaer, Thomas, additional, Bustamante, Sandra, additional, Byun, Do-Young, additional, Carlstrom, John E., additional, Ceccobello, Chiara, additional, Chael, Andrew, additional, Chatterjee, Koushik, additional, Chatterjee, Shami, additional, Chen, Ming-Tang, additional, Chen, Yongjun, additional, Cheng, Xiaopeng, additional, Christian, Pierre, additional, Conroy, Nicholas S., additional, Conway, John E., additional, Cordes, James M., additional, Crawford, Thomas M., additional, Crew, Geoffrey B., additional, Cruz-Osorio, Alejandro, additional, Cui, Yuzhu, additional, Davelaar, Jordy, additional, De Laurentis, Mariafelicia, additional, Deane, Roger, additional, Dempsey, Jessica, additional, Desvignes, Gregory, additional, Dexter, Jason, additional, Dhruv, Vedant, additional, Doeleman, Sheperd S., additional, Dougal, Sean, additional, Dzib, Sergio A., additional, Eatough, Ralph P., additional, Emami, Razieh, additional, Falcke, Heino, additional, Farah, Joseph, additional, Fish, Vincent L., additional, Fomalont, Ed, additional, Ford, H. Alyson, additional, Fraga-Encinas, Raquel, additional, Freeman, William T., additional, Friberg, Per, additional, Fromm, Christian M., additional, Galison, Peter, additional, Gammie, Charles F., additional, García, Roberto, additional, Gentaz, Olivier, additional, Georgiev, Boris, additional, Goddi, Ciriaco, additional, Gold, Roman, additional, Gómez-Ruiz, Arturo I., additional, Gu, Minfeng, additional, Hada, Kazuhiro, additional, Haggard, Daryl, additional, Haworth, Kari, additional, Hecht, Michael H., additional, Hesper, Ronald, additional, Heumann, Dirk, additional, Ho, Luis C., additional, Ho, Paul, additional, Honma, Mareki, additional, Huang, Chih-Wei L., additional, Huang, Lei, additional, Hughes, David H., additional, Ikeda, Shiro, additional, Impellizzeri, C. M. Violette, additional, Inoue, Makoto, additional, James, David J., additional, Jannuzi, Buell T., additional, Jeter, Britton, additional, Jiang, Wu, additional, Jiménez-Rosales, Alejandra, additional, Joshi, Abhishek V., additional, Jung, Taehyun, additional, Karami, Mansour, additional, Karuppusamy, Ramesh, additional, Kawashima, Tomohisa, additional, Keating, Garrett K., additional, Kettenis, Mark, additional, Kim, Dong-Jin, additional, Kim, Jongsoo, additional, Kim, Junhan, additional, Kino, Motoki, additional, Koay, Jun Yi, additional, Kocherlakota, Prashant, additional, Kofuji, Yutaro, additional, Koyama, Shoko, additional, Kramer, Carsten, additional, Kramer, Michael, additional, Kuo, Cheng-Yu, additional, La Bella, Noemi, additional, Lauer, Tod R., additional, Lee, Daeyoung, additional, Lee, Sang-Sung, additional, Leung, Po Kin, additional, Levis, Aviad, additional, Li, Zhiyuan, additional, Lindahl, Greg, additional, Lindqvist, Michael, additional, Lisakov, Mikhail, additional, Liu, Kuo, additional, Liuzzo, Elisabetta, additional, Lo, Wen-Ping, additional, Lobanov, Andrei P., additional, Loinard, Laurent, additional, Lonsdale, Colin J., additional, MacDonald, Nicholas R., additional, Mao, Jirong, additional, Marchili, Nicola, additional, Markoff, Sera, additional, Marrone, Daniel P., additional, Marscher, Alan P., additional, Matsushita, Satoki, additional, Matthews, Lynn D., additional, Medeiros, Lia, additional, Menten, Karl M., additional, Michalik, Daniel, additional, Mizuno, Izumi, additional, Mizuno, Yosuke, additional, Moran, James M., additional, Moriyama, Kotaro, additional, Müller, Cornelia, additional, Mus, Alejandro, additional, Musoke, Gibwa, additional, Myserlis, Ioannis, additional, Nadolski, Andrew, additional, Nagai, Hiroshi, additional, Nagar, Neil M., additional, Nakamura, Masanori, additional, Narayan, Ramesh, additional, Narayanan, Gopal, additional, Natarajan, Iniyan, additional, Nathanail, Antonios, additional, Fuentes, Santiago Navarro, additional, Neilsen, Joey, additional, Neri, Roberto, additional, Ni, Chunchong, additional, Noutsos, Aristeidis, additional, Nowak, Michael A., additional, Oh, Junghwan, additional, Okino, Hiroki, additional, Olivares, Héctor, additional, Ortiz-León, Gisela N., additional, Oyama, Tomoaki, additional, Özel, Feryal, additional, Palumbo, Daniel C. M., additional, Paraschos, Georgios Filippos, additional, Park, Jongho, additional, Parsons, Harriet, additional, Patel, Nimesh, additional, Pen, Ue-Li, additional, Piétu, Vincent, additional, Plambeck, Richard, additional, PopStefanija, Aleksandar, additional, Porth, Oliver, additional, Prather, Ben, additional, Preciado-López, Jorge A., additional, Psaltis, Dimitrios, additional, Pu, Hung-Yi, additional, Rao, Ramprasad, additional, Rawlings, Mark G., additional, Raymond, Alexander W., additional, Rezzolla, Luciano, additional, Ricarte, Angelo, additional, Ripperda, Bart, additional, Roelofs, Freek, additional, Rogers, Alan, additional, Ros, Eduardo, additional, Romero-Cañizales, Cristina, additional, Roshanineshat, Arash, additional, Rottmann, Helge, additional, Roy, Alan L., additional, Ruiz, Ignacio, additional, Ruszczyk, Chet, additional, Rygl, Kazi L. J., additional, Sánchez, Salvador, additional, Sánchez-Argüelles, David, additional, Sánchez-Portal, Miguel, additional, Sasada, Mahito, additional, Satapathy, Kaushik, additional, Savolainen, Tuomas, additional, Schloerb, F. Peter, additional, Schonfeld, Jonathan, additional, Schuster, Karl-Friedrich, additional, Shao, Lijing, additional, Shen, Zhiqiang, additional, Small, Des, additional, Sohn, Bong Won, additional, SooHoo, Jason, additional, Souccar, Kamal, additional, Sun, He, additional, Tazaki, Fumie, additional, Tetarenko, Alexandra J., additional, Tiede, Paul, additional, Tilanus, Remo P. J., additional, Titus, Michael, additional, Torne, Pablo, additional, Trent, Tyler, additional, Trippe, Sascha, additional, Turk, Matthew, additional, van Langevelde, Huib Jan, additional, van Rossum, Daniel R., additional, Vos, Jesse, additional, Wagner, Jan, additional, Ward-Thompson, Derek, additional, Wardle, John, additional, Weintroub, Jonathan, additional, Wex, Norbert, additional, Wharton, Robert, additional, Wiik, Kaj, additional, Witzel, Gunther, additional, Wondrak, Michael F., additional, Wong, George N., additional, Wu, Qingwen, additional, Yamaguchi, Paul, additional, Yoon, Doosoo, additional, Young, André, additional, Young, Ken, additional, Younsi, Ziri, additional, Yuan, Feng, additional, Yuan, Ye-Fei, additional, Zensus, J. Anton, additional, Zhang, Shuo, additional, and Zhao, Shan-Shan, additional

Published
2023
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46. Star Formation, Observations

Author

Narayanan, Gopal, Gargaud, Muriel, editor, Amils, Ricardo, editor, Quintanilla, José Cernicharo, editor, Cleaves, Henderson James (Jim), II, editor, Irvine, William M., editor, Pinti, Daniele L., editor, and Viso, Michel, editor

Published
2011
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47. A Statistical Model for Quantized AC Block DCT Coefficients in JPEG Compression and its Application to Detecting Potential Compression History in Bitmap Images

Author

Narayanan, Gopal, Shi, Yun Qing, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Kim, Hyoung-Joong, editor, Shi, Yun Qing, editor, and Barni, Mauro, editor

Published
2011
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49. Resolving the Inner Parsec of the Blazar J1924–2914 with the Event Horizon Telescope

Author

Issaoun, Sara, primary, Wielgus, Maciek, additional, Jorstad, Svetlana, additional, Krichbaum, Thomas P., additional, Blackburn, Lindy, additional, Janssen, Michael, additional, Chan, Chi-kwan, additional, Pesce, Dominic W., additional, Gómez, José L., additional, Akiyama, Kazunori, additional, Mościbrodzka, Monika, additional, Martí-Vidal, Iván, additional, Chael, Andrew, additional, Lico, Rocco, additional, Liu, Jun, additional, Ramakrishnan, Venkatessh, additional, Lisakov, Mikhail, additional, Fuentes, Antonio, additional, Zhao, Guang-Yao, additional, Moriyama, Kotaro, additional, Broderick, Avery E., additional, Tiede, Paul, additional, MacDonald, Nicholas R., additional, Mizuno, Yosuke, additional, Traianou, Efthalia, additional, Loinard, Laurent, additional, Davelaar, Jordy, additional, Gurwell, Mark, additional, Lu, Ru-Sen, additional, Alberdi, Antxon, additional, Alef, Walter, additional, Algaba, Juan Carlos, additional, Anantua, Richard, additional, Asada, Keiichi, additional, Azulay, Rebecca, additional, Bach, Uwe, additional, Baczko, Anne-Kathrin, additional, Ball, David, additional, Baloković, Mislav, additional, Barrett, John, additional, Bauböck, Michi, additional, Benson, Bradford A., additional, Bintley, Dan, additional, Blundell, Raymond, additional, Boland, Wilfred, additional, Bouman, Katherine L., additional, Bower, Geoffrey C., additional, Boyce, Hope, additional, Bremer, Michael, additional, Brinkerink, Christiaan D., additional, Brissenden, Roger, additional, Britzen, Silke, additional, Broguiere, Dominique, additional, Bronzwaer, Thomas, additional, Bustamante, Sandra, additional, Byun, Do-Young, additional, Carlstrom, John E., additional, Ceccobello, Chiara, additional, Chatterjee, Koushik, additional, Chatterjee, Shami, additional, Chen, Ming-Tang, additional, Chen, Yongjun, additional, Cho, Ilje, additional, Christian, Pierre, additional, Conroy, Nicholas S., additional, Conway, John E., additional, Cordes, James M., additional, Crawford, Thomas M., additional, Crew, Geoffrey B., additional, Cruz-Osorio, Alejandro, additional, Cui, Yuzhu, additional, Laurentis, Mariafelicia De, additional, Deane, Roger, additional, Dempsey, Jessica, additional, Desvignes, Gregory, additional, Dexter, Jason, additional, Doeleman, Sheperd S., additional, Dhruv, Vedant, additional, Dzib Quijano, Sergio Abraham, additional, Eatough, Ralph P., additional, Emami, Razieh, additional, Falcke, Heino, additional, Farah, Joseph, additional, Fish, Vincent L., additional, Fomalont, Ed, additional, Ford, H. Alyson, additional, Fraga-Encinas, Raquel, additional, Freeman, William T., additional, Friberg, Per, additional, Fromm, Christian M., additional, Galison, Peter, additional, Gammie, Charles F., additional, García, Roberto, additional, Gentaz, Olivier, additional, Georgiev, Boris, additional, Goddi, Ciriaco, additional, Gold, Roman, additional, Gómez-Ruiz, Arturo I., additional, Gu, Minfeng, additional, Hada, Kazuhiro, additional, Haggard, Daryl, additional, Hecht, Michael H., additional, Hesper, Ronald, additional, Ho, Luis C., additional, Ho, Paul, additional, Honma, Mareki, additional, Huang, Chih-Wei L., additional, Huang, Lei, additional, Hughes, David H., additional, Ikeda, Shiro, additional, Impellizzeri, C. M. Violette, additional, Inoue, Makoto, additional, James, David J., additional, Jannuzi, Buell T., additional, Jeter, Britton, additional, Jiang, Wu, additional, Jimenez-Rosales, Alejandra, additional, Johnson, Michael D., additional, Joshi, Abhishek V., additional, Jung, Taehyun, additional, Karami, Mansour, additional, Karuppusamy, Ramesh, additional, Kawashima, Tomohisa, additional, Keating, Garrett K., additional, Kettenis, Mark, additional, Kim, Dong-Jin, additional, Kim, Jae-Young, additional, Kim, Jongsoo, additional, Kim, Junhan, additional, Kino, Motoki, additional, Koay, Jun Yi, additional, Kocherlakota, Prashant, additional, Kofuji, Yutaro, additional, Koch, Patrick M., additional, Koyama, Shoko, additional, Kramer, Carsten, additional, Kramer, Michael, additional, Kuo, Cheng-Yu, additional, Bella, Noemi La, additional, Lauer, Tod R., additional, Lee, Daeyoung, additional, Lee, Sang-Sung, additional, Leung, Po Kin, additional, Levis, Aviad, additional, Li, Zhiyuan, additional, Lindahl, Greg, additional, Lindqvist, Michael, additional, Liu, Kuo, additional, Liuzzo, Elisabetta, additional, Lo, Wen-Ping, additional, Lobanov, Andrei P., additional, Lonsdale, Colin, additional, Mao, Jirong, additional, Marchili, Nicola, additional, Markoff, Sera, additional, Marrone, Daniel P., additional, Marscher, Alan P., additional, Matsushita, Satoki, additional, Matthews, Lynn D., additional, Medeiros, Lia, additional, Menten, Karl M., additional, Michalik, Daniel, additional, Mizuno, Izumi, additional, Moran, James M., additional, Müller, Cornelia, additional, Mus, Alejandro, additional, Musoke, Gibwa, additional, Myserlis, Ioannis, additional, Nadolski, Andrew, additional, Nagai, Hiroshi, additional, Nagar, Neil M., additional, Nakamura, Masanori, additional, Narayan, Ramesh, additional, Narayanan, Gopal, additional, Natarajan, Iniyan, additional, Nathanail, Antonios, additional, Neilsen, Joey, additional, Neri, Roberto, additional, Ni, Chunchong, additional, Noutsos, Aristeidis, additional, Nowak, Michael A., additional, Oh, Junghwan, additional, Okino, Hiroki, additional, Olivares, Héctor, additional, Ortiz-León, Gisela N., additional, Oyama, Tomoaki, additional, Özel, Feryal, additional, Palumbo, Daniel C. M., additional, Paraschos, Georgios Filippos, additional, Park, Jongho, additional, Parsons, Harriet, additional, Patel, Nimesh, additional, Pen, Ue-Li, additional, Piétu, Vincent, additional, Plambeck, Richard, additional, PopStefanija, Aleksandar, additional, Porth, Oliver, additional, Pötzl, Felix M., additional, Prather, Ben, additional, Preciado-López, Jorge A., additional, Psaltis, Dimitrios, additional, Pu, Hung-Yi, additional, Rao, Ramprasad, additional, Rawlings, Mark G., additional, Raymond, Alexander W., additional, Rezzolla, Luciano, additional, Ricarte, Angelo, additional, Ripperda, Bart, additional, Roelofs, Freek, additional, Rogers, Alan, additional, Ros, Eduardo, additional, Romero-Canizales, Cristina, additional, Roshanineshat, Arash, additional, Rottmann, Helge, additional, Roy, Alan L., additional, Ruiz, Ignacio, additional, Ruszczyk, Chet, additional, Rygl, Kazi L. J., additional, Sánchez, Salvador, additional, Sánchez-Arguelles, David, additional, Sanchez-Portal, Miguel, additional, Sasada, Mahito, additional, Satapathy, Kaushik, additional, Savolainen, Tuomas, additional, Schloerb, F. Peter, additional, Schuster, Karl-Friedrich, additional, Shao, Lijing, additional, Shen, Zhiqiang, additional, Small, Des, additional, Sohn, Bong Won, additional, SooHoo, Jason, additional, Souccar, Kamal, additional, Sun, He, additional, Tazaki, Fumie, additional, Tetarenko, Alexandra J., additional, Tilanus, Remo P. J., additional, Titus, Michael, additional, Torne, Pablo, additional, Trent, Tyler, additional, Trippe, Sascha, additional, van Bemmel, Ilse, additional, van Langevelde, Huib Jan, additional, van Rossum, Daniel R., additional, Vos, Jesse, additional, Wagner, Jan, additional, Ward-Thompson, Derek, additional, Wardle, John, additional, Weintroub, Jonathan, additional, Wex, Norbert, additional, Wharton, Robert, additional, Wiik, Kaj, additional, Witzel, Gunther, additional, Wondrak, Michael, additional, Wong, George N., additional, Wu, Qingwen, additional, Yamaguchi, Paul, additional, Yoon, Doosoo, additional, Young, André, additional, Young, Ken, additional, Younsi, Ziri, additional, Yuan, Feng, additional, Yuan, Ye-Fei, additional, Zensus, J. Anton, additional, Zhang, Shuo, additional, and Zhao, Shan-Shan, additional

Published
2022
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50. The Variability of the Black Hole Image in M87 at the Dynamical Timescale

Author

Satapathy, Kaushik, Psaltis, Dimitrios, Özel, Feryal, Medeiros, Lia, Dougall, Sean T., Chan, Chi-Kwan, Wielgus, Maciek, Prather, Ben S., Wong, George N., Gammie, Charles F., Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Baczko, Anne-Kathrin, Ball, David, Baloković, Mislav, Barrett, John, Benson, Bradford A., Bintley, Dan, Blackburn, Lindy, Blundell, Raymond, Boland, Wilfred, Bouman, Katherine L., Bower, Geoffrey C., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Broguiere, Dominique, Bronzwaer, Thomas, Bustamente, Sandra, Byun, Do-Young, Carlstrom, John E., Chael, Andrew, Chatterjee, Koushik, Chatterjee, Shami, Chen, Ming-Tang, Chen, Yongjun, Cho, Ilje, Christian, Pierre, Conway, John E., Cordes, James M., Crawford, Thomas M., Crew, Geoffrey B., Cruz-Osorio, Alejandro, Cui, Yuzhu, Davelaar, Jordy, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Dexter, Jason, Doeleman, Sheperd S., Eatough, Ralph P., Falcke, Heino, Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Ford, H. Alyson, Fraga-Encinas, Raquel, Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, García, Roberto, Gentaz, Olivier, Georgiev, Boris, Goddi, Ciriaco, Gold, Roman, Gómez-Ruiz, Arturo I., Gómez, José L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Hecht, Michael H., Hesper, Ronald, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Janssen, Michael, Jeter, Britton, Jiang, Wu, Jimenez-Rosales, Alejandra, Johnson, Michael D., Jorstad, Svetlana, Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kofuji, Yutaro, Koch, Patrick M., Koyama, Shoko, Kramer, Carsten, Kramer, Michael, Krichbaum, Thomas P., Kuo, Cheng-Yu, Lauer, Tod R., Lee, Sang-Sung, Levis, Aviad, Li, Yan-Rong, Li, Zhiyuan, Lindqvist, Michael, Lico, Rocco, Lindahl, Greg, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lo, Wen-Ping, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin, Lu, Ru-Sen, MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Martí-Vidal, Iván, Matsushita, Satoki, Matthews, Lynn D., Menten, Karl M., Mizuno, Izumi, Mizuno, Yosuke, Moran, James M., Moriyama, Kotaro, Moscibrodzka, Monika, Müller, Cornelia, Mejías, Alejandro Mus, Musoke, Gibwa, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayan, Ramesh, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Neilsen, Joey, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Okino, Hiroki, Olivares, Héctor, Ortiz-León, Gisela N., Oyama, Tomoaki, Palumbo, Daniel C. M., Park, Jongho, Patel, Nimesh, Pen, Ue-Li, Pesce, Dominic W., Piétu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Pötzl, Felix M., Preciado-López, Jorge A., Pu, Hung-Yi, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Raymond, Alexander W., Rezzolla, Luciano, Ripperda, Bart, Roelofs, Freek, Rogers, Alan, Ros, Eduardo, Rose, Mel, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruszczyk, Chet, Rygl, Kazi L. J., Sánchez, Salvador, Sánchez-Arguelles, David, Sasada, Mahito, Savolainen, Tuomas, Schloerb, F. Peter, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Toma, Kenji, Torne, Pablo, Traianou, Efthalia, Trent, Tyler, Trippe, Sascha, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Wagner, Jan, Ward-Thompson, Derek, Wardle, John, Weintroub, Jonathan, Wex, Norbert, Wharton, Robert, Wiik, Kaj, Wu, Qingwen, Yoon, Doosoo, Young, André, Young, Ken, Younsi, Ziri, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhao, Guang-Yao, Zhao, Shan-Shan, Satapathy, Kaushik, Psaltis, Dimitrios, Özel, Feryal, Medeiros, Lia, Dougall, Sean T., Chan, Chi-Kwan, Wielgus, Maciek, Prather, Ben S., Wong, George N., Gammie, Charles F., Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Baczko, Anne-Kathrin, Ball, David, Baloković, Mislav, Barrett, John, Benson, Bradford A., Bintley, Dan, Blackburn, Lindy, Blundell, Raymond, Boland, Wilfred, Bouman, Katherine L., Bower, Geoffrey C., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Broguiere, Dominique, Bronzwaer, Thomas, Bustamente, Sandra, Byun, Do-Young, Carlstrom, John E., Chael, Andrew, Chatterjee, Koushik, Chatterjee, Shami, Chen, Ming-Tang, Chen, Yongjun, Cho, Ilje, Christian, Pierre, Conway, John E., Cordes, James M., Crawford, Thomas M., Crew, Geoffrey B., Cruz-Osorio, Alejandro, Cui, Yuzhu, Davelaar, Jordy, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Dexter, Jason, Doeleman, Sheperd S., Eatough, Ralph P., Falcke, Heino, Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Ford, H. Alyson, Fraga-Encinas, Raquel, Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, García, Roberto, Gentaz, Olivier, Georgiev, Boris, Goddi, Ciriaco, Gold, Roman, Gómez-Ruiz, Arturo I., Gómez, José L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Hecht, Michael H., Hesper, Ronald, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Janssen, Michael, Jeter, Britton, Jiang, Wu, Jimenez-Rosales, Alejandra, Johnson, Michael D., Jorstad, Svetlana, Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kofuji, Yutaro, Koch, Patrick M., Koyama, Shoko, Kramer, Carsten, Kramer, Michael, Krichbaum, Thomas P., Kuo, Cheng-Yu, Lauer, Tod R., Lee, Sang-Sung, Levis, Aviad, Li, Yan-Rong, Li, Zhiyuan, Lindqvist, Michael, Lico, Rocco, Lindahl, Greg, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lo, Wen-Ping, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin, Lu, Ru-Sen, MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Martí-Vidal, Iván, Matsushita, Satoki, Matthews, Lynn D., Menten, Karl M., Mizuno, Izumi, Mizuno, Yosuke, Moran, James M., Moriyama, Kotaro, Moscibrodzka, Monika, Müller, Cornelia, Mejías, Alejandro Mus, Musoke, Gibwa, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayan, Ramesh, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Neilsen, Joey, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Okino, Hiroki, Olivares, Héctor, Ortiz-León, Gisela N., Oyama, Tomoaki, Palumbo, Daniel C. M., Park, Jongho, Patel, Nimesh, Pen, Ue-Li, Pesce, Dominic W., Piétu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Pötzl, Felix M., Preciado-López, Jorge A., Pu, Hung-Yi, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Raymond, Alexander W., Rezzolla, Luciano, Ripperda, Bart, Roelofs, Freek, Rogers, Alan, Ros, Eduardo, Rose, Mel, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruszczyk, Chet, Rygl, Kazi L. J., Sánchez, Salvador, Sánchez-Arguelles, David, Sasada, Mahito, Savolainen, Tuomas, Schloerb, F. Peter, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Toma, Kenji, Torne, Pablo, Traianou, Efthalia, Trent, Tyler, Trippe, Sascha, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Wagner, Jan, Ward-Thompson, Derek, Wardle, John, Weintroub, Jonathan, Wex, Norbert, Wharton, Robert, Wiik, Kaj, Wu, Qingwen, Yoon, Doosoo, Young, André, Young, Ken, Younsi, Ziri, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhao, Guang-Yao, and Zhao, Shan-Shan

Abstract

The black hole images obtained with the Event Horizon Telescope (EHT) are expected to be variable at the dynamical timescale near their horizons. For the black hole at the center of the M87 galaxy, this timescale (5–61 days) is comparable to the 6 day extent of the 2017 EHT observations. Closure phases along baseline triangles are robust interferometric observables that are sensitive to the expected structural changes of the images but are free of station-based atmospheric and instrumental errors. We explored the day-to-day variability in closure-phase measurements on all six linearly independent nontrivial baseline triangles that can be formed from the 2017 observations. We showed that three triangles exhibit very low day-to-day variability, with a dispersion of ∼3°–5°. The only triangles that exhibit substantially higher variability (∼90°–180°) are the ones with baselines that cross the visibility amplitude minima on the u–v plane, as expected from theoretical modeling. We used two sets of general relativistic magnetohydrodynamic simulations to explore the dependence of the predicted variability on various black hole and accretion-flow parameters. We found that changing the magnetic field configuration, electron temperature model, or black hole spin has a marginal effect on the model consistency with the observed level of variability. On the other hand, the most discriminating image characteristic of models is the fractional width of the bright ring of emission. Models that best reproduce the observed small level of variability are characterized by thin ring-like images with structures dominated by gravitational lensing effects and thus least affected by turbulence in the accreting plasmas.

Published
2022

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