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12 results on '"Stephan O'Brien"'

1. TeV and optical observations of the Be/pulsar binary 1A0535+262 during the 2020 giant outburst

Author

Matthew Lundy, Massimo Capasso, Rene Ong, Iftach Sadeh, Philip Kaaret, Weidong Jin, Wystan Benbow, Reshmi Mukherjee, Raul Prado, Sameer Patel, Patrick Moriarty, Gernot Maier, Amy Furniss, Ken Ragan, David Williams, James Buckley, Lucy Fortson, John Quinn, Jamie Holder, Chiara Giuri, Elisa Pueschel, Daniel Nieto, Colin Adams, Stephan O'Brien, Deivid Ribeiro, Konstantin Pfrang, Orel Gueta, Gregory M Foote, Amanda Weinstein, Sajan Kumar, Tyler Williamson, Donggeun Tak, Conor McGrath, Tobias Kai Kleiner, Martin Pohl, Paul Reynolds, Binita Hona, David Hanna, Marcos Santander, Glenn Sembroski, Sonal Ramesh Patel, Manel Errando, Mary Kertzman, Olivier Hervet, Mireia Nievas-Rosillo, Mark Lang, Emmet Roache, Thomas Brian Humensky, Ruo-Yu Shang, Vladimir Vassiliev, Alisha Chromey, Abe Falcone, Jodi Christiansen, Adam Otte, Alasdair E. Gent, Aryeh Brill, James Ryan, Kayla Farrell, Gary Gillanders, Qi Feng, Avery Archer, and David Kieda

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, Binary number, FOS: Physical sciences, Cosmic ray, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Binary pulsar, law.invention, Pulsar, law, Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation, Flare
Abstract

1A 0535+262 is a Be X-ray binary pulsar and one of the only galactic pulsar systems to show radio jet emission. Characterizing the very high energy emission (VHE, >100 GeV) in these extreme microquasars is critical to understanding their contribution to the origin of galactic cosmic rays. The 2020 giant outburst of this system, where X-ray fluxes exceeded 12 Crab, marked a rare opportunity to investigate the gamma-ray and rapid optical variability of these transient systems while in such an extreme state. This month of activity marked the brightest flare measured in this system. VERITAS's developing optical capabilities in tandem with the ability to measure TeV gamma rays allowed for a unique campaign to be undertaken. VERITAS's observations of this system during the outburst will be presented in the context of observations at lower energies and previous observations of this system by imaging atmospheric Cherenkov telescopes.

Published
2021

2. Gamma-ray and Optical Observations of Repeating Fast Radio Bursts with VERITAS

Author

Matthew Lundy, Massimo Capasso, Rene Ong, Iftach Sadeh, Philip Kaaret, Weidong Jin, Wystan Benbow, Reshmi Mukherjee, Raul Prado, Sameer Patel, Patrick Moriarty, Gernot Maier, Amy Furniss, Ken Ragan, David Williams, James Buckley, Lucy Fortson, John Quinn, Jamie Holder, Chiara Giuri, Elisa Pueschel, Daniel Nieto, Colin Adams, Stephan O'Brien, Deivid Ribeiro, Konstantin Pfrang, Orel Gueta, Gregory M Foote, Amanda Weinstein, Sajan Kumar, Tyler Williamson, Donggeun Tak, Conor McGrath, Tobias Kai Kleiner, Martin Pohl, Paul Reynolds, Binita Hona, David Hanna, Marcos Santander, Glenn Sembroski, Sonal Ramesh Patel, Manel Errando, Mary Kertzman, Olivier Hervet, Mireia Nievas-Rosillo, Mark Lang, Emmet Roache, Thomas Brian Humensky, Ruo-Yu Shang, Vladimir Vassiliev, Alisha Chromey, Abe Falcone, Jodi Christiansen, Adam Otte, Alasdair E. Gent, Aryeh Brill, James Ryan, Kayla Farrell, Gary Gillanders, Qi Feng, Avery Archer, and David Kieda

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Millisecond, Fast radio burst, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, Theoretical models, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Magnetar, Radio telescope, Rapid rise, Astrophysics - High Energy Astrophysical Phenomena
Abstract

Fast radio burst (FRBs) are an exciting class of bright, extragalactic, millisecond radio transients. The recent development of large field-of-view (FOV) radio telescopes has caused a rapid rise in the number of identified single burst and repeating FRBs. This has allowed for the extensive multi-wavelength follow-up to search for the potential counterparts predicted by theoretical models. New observations of similar radio transients in Galactic magnetars like SGR 1935+2154 have continued to motivate the search for rapid optical and very-high-energy (VHE, >100 GeV) counterparts. Since 2016 VERITAS has engaged in an FRB observing campaign to search for the prompt optical, and VHE emission from multiple repeating FRBs. We present these new results from VERITAS observations of five repeating sources including data taken simultaneously with bursts observed by the CHIME radio telescope.

Published
2021
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3. Calibration of Aerogel Tiles for the HELIX-RICH Detector

Author

Stephan O'Brien

Subjects
Physics, Silicon photomultiplier, Physics::Instrumentation and Detectors, Helix, Detector, Calibration, High Energy Physics::Experiment, Aerogel, Superconducting magnet, Atomic physics, Refractive index, Cherenkov radiation
Abstract

HELIX (High Energy Light Isotope eXperiment) is a balloon-borne instrument designed to measure the chemical and isotopic abundances of light cosmic-ray nuclei. In particular, HELIX is optimized to measure $^{10}$Be and $^{9}$Be in the range 0.2 GeV/n to beyond 3 GeV/n. To achieve this, HELIX utilizes a 1 Tesla superconducting magnet with a high-resolution gas drift tracking system, time-of-flight detector, and a ring-imaging Cherenkov (RICH) detector. The RICH detector consists of aerogel tile radiators (refractive index ~1.15) with a silicon photomultiplier detector plane. To adequately discriminate between $^{10}$Be and $^{9}$Be isotopes, the refractive index of the aerogel tiles must be known to a precision of 0.1%. In this contribution, detailed mapping of the refractive index across the aerogel tiles is presented and the methodology used to obtain these measurements is discussed.

Published
2021
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4. VERITAS follow-up observation of the blazar TXS 0506+056

Author

Weidong Jin, RileyAnne Sharpe, Massimo Capasso, Rene Ong, Iftach Sadeh, Philip Kaaret, Wystan Benbow, Reshmi Mukherjee, Raul Prado, Matthew Lundy, Sameer Patel, Patrick Moriarty, Gernot Maier, Amy Furniss, Ken Ragan, David Williams, James Buckley, Lucy Fortson, John Quinn, Jamie Holder, Chiara Giuri, Elisa Pueschel, Daniel Nieto, Colin Adams, Stephan O'Brien, Deivid Ribeiro, Konstantin Pfrang, Orel Gueta, Gregory M Foote, Amanda Weinstein, Sajan Kumar, Tyler Williamson, Donggeun Tak, Conor McGrath, Tobias Kai Kleiner, Martin Pohl, Paul Reynolds, Binita Hona, David Hanna, Marcos Santander, Glenn Sembroski, Sonal Ramesh Patel, Manel Errando, Mary Kertzman, Olivier Hervet, Mireia Nievas-Rosillo, Mark Lang, Emmet Roache, Thomas Brian Humensky, Ruo-Yu Shang, Vladimir Vassiliev, Alisha Chromey, Abe Falcone, Jodi Christiansen, Adam Otte, Alasdair E. Gent, Aryeh Brill, James Ryan, Kayla Farrell, Gary Gillanders, Qi Feng, Avery Archer, and David Kieda

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), High energy, Astrophysics::High Energy Astrophysical Phenomena, Flux, FOS: Physical sciences, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 13. Climate action, Observatory, QUIET, Neutrino, Astrophysics - High Energy Astrophysical Phenomena, Blazar, Event (particle physics)
Abstract

The gamma-ray blazar TXS 0506+056 was found with an enhanced gamma-ray emission state in spatial and temporal coincidence with the IceCube high energy neutrino event IC170922A. This is the most significant association by far between a high-energy neutrino event and a blazar in a flaring state. Studying the time evolution and spectral behavior of the blazar emission may help in identifying the sources of the diffuse neutrino flux observed by IceCube and the origin of energetic cosmic rays. TXS 0506+056 was detected by the VERITAS gamma-ray observatory with a significance of 5.8 standard deviations above 110 GeV in a 35 hour data set collected between September 23, 2017 and February 6, 2018. Here we will present results from recent VERITAS observations and an associated multiwavelength campaign, collected between October 10, 2018 to March 1, 2021. A relatively quiet very high energy gamma-ray emission state was observed during this time period, and flux upper limits are used to constrain the potential variability of this blazar.

Published
2021
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5. Challenges of starting treatment protocols for acute lymphoblastic leukaemia in a low‐income setting — the Blantyre experience

Author

Angela Dunsmure, Eunice Chakumatha, Anthony V. Moorman, Trijn Israels, Peter Carey, Emilio Barretta, Eloise S. Rogers, Elizabeth Molyneux, Edward C. Schwalbe, Stephan O’Brien, George Chagaluka, and Simon Bailey

Subjects
Low income, Malawi, medicine.medical_specialty, Treatment outcome, MEDLINE, Original research, 03 medical and health sciences, 0302 clinical medicine, Internal medicine, Antineoplastic Combined Chemotherapy Protocols, medicine, Humans, Intensive care medicine, Developing Countries, Hematology, business.industry, Induction chemotherapy, A100, Induction Chemotherapy, Precursor Cell Lymphoblastic Leukemia-Lymphoma, B900, Treatment Outcome, Socioeconomic Factors, 030220 oncology & carcinogenesis, Lymphoblastic leukaemia, business, 030215 immunology
Abstract

The British Journal of Haematology publishes original research papers in clinical, laboratory and experimental haematology. The Journal also features annotations, reviews, short reports, images in haematology and Letters to the Editor.

Published
2020
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6. Production of Silica Aerogel Radiator Tiles for the HELIX RICH Detector

Author

Nahee Park, David Hanna, S. L. Nutter, Dietrich Müller, M. Gebhard, Tyler Werner, I. G. Wisher, Gerard Visser, Emma Ellingwood, Patrick Allison, Thomas Rosin, S. P. Wakely, A. D. Tomasch, Yu Chen, S. I. Mognet, Gregory Tarle, Noah Green, S. Coutu, Kelli Michaels, Ethan Schreyer, J. A. Musser, K. McBride, Makoto Tabata, Rostom Mbarek, Lucas Beaufore, J. J. Beatty, Monong Yu, Brandon Kunkler, and Stephan O'Brien

Subjects
Materials science, chemistry, Spectrometer, Physics::Instrumentation and Detectors, Aluminium, Detector, Radiator (engine cooling), Analytical chemistry, chemistry.chemical_element, Context (language use), Aerogel, Refractive index, Cherenkov radiation
Abstract

A hydrophobic, highly transparent silica aerogel with a refractive index of $\sim $1.15 was developed using sol–gel polymerization, pin drying, and supercritical carbon dioxide solvent extraction technologies. A total of 96 monolithic tiles with dimensions of 11 cm $\times $ 11 cm $\times $ 1 cm were mass produced with a high crack-free yield for use as Cherenkov radiators to be installed in the proximity-focusing ring-imaging Cherenkov (RICH) detector. The RICH detector, containing 36 aerogel tiles, will be installed in the High Energy Light Isotope eXperiment (HELIX) spectrometer and used to measure the velocity of cosmic-ray particles. HELIX is a balloon-borne experimental program designed to measure the chemical and isotopic abundances of light cosmic-ray nuclei. A water-jet cut test of the aerogel tiles and a gluing test of the trimmed tiles with dimensions of 10 cm $\times $ 10 cm $\times $ 1 cm in an aluminum frame were successful in the context of integration into the radiator module.

Published
2019
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7. Calibration of the Aerogel Tiles for the HELIX RICH

Author

J. J. Beatty, Gerard Visser, Makoto Tabata, S. P. Wakely, S. L. Nutter, Rostom Mbarek, Ethan Schreyer, A. D. Tomasch, Tyler Werner, Stephan O'Brien, S. Coutu, Noah Green, Emma Ellingwood, Thomas Rosin, Gregory Tarle, Yu Chen, J. A. Musser, Mark Gebharb, S. I. Mognet, Monong Yu, I. G. Wisher, Nahee Park, Kelli Michaels, Brandon Kunkler, K. McBride, Patrick Allison, Dietrich Müller, David Hanna, and Lucas Beaufore

Subjects
Physics, Isotope, Physics::Instrumentation and Detectors, Cherenkov detector, Detector, Cosmic ray, Aerogel, Superconducting magnet, law.invention, Silicon photomultiplier, law, Physics::Atomic Physics, Atomic physics, Refractive index
Abstract

HELIX (High Energy Light Isotope eXperiment) is a balloon-borne experiment designed to measure the chemical and isotopic abundances of light cosmic ray nuclei, especially the $^{\textrm{10}}\textrm{Be}/^{\textrm{9}}\textrm{Be}$ ratio over the energy range from 0.2 GeV/n to beyond 3 GeV/n. This is a key measurement for constraining cosmic-ray propagation models. The detector is a mass spectrometer, which is built around a 1 Tesla superconducting magnet and a high-resolution tracking system to determine particle rigidity. Time-of-flight counters and a ring-imaging Cherenkov detector (RICH) are used to measure velocities. The proximity-focused RICH consists of a radiator made of aerogel tiles (refractive index approximately 1.15) and a detector plane of silicon photomultipliers. For discrimination of the $^{\textrm{9}}\textrm{Be}$ and $^{\textrm{10}}\textrm{Be}$ isotopes at high energy, the refractive index of the aerogel must be known to a precision of 0.07%. Given the manufacturing tolerances in the production process, the index must be mapped over the lateral extent of aerogel tiles on a fine grid. In this contribution, we describe and show initial results from procedures developed for this task. These include laser-deflection and electron-beam measurements.

Published
2019
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8. Maximum likelihood spectral fitting and its application to EBL constraints

Author

Stephan O'Brien

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), COSMIC cancer database, Astrophysics::High Energy Astrophysical Phenomena, Cosmic microwave background, Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Spectral line, Redshift, Extragalactic background light, Blazar, Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation
Abstract

The extragalactic background light (EBL) is the second-most-intense form of cosmic background light (the first being the cosmic microwave background) and contains the redshifted optical radiation, from infra-red to ultraviolet, emitted across all epochs, making it of great cosmological interest. While direct measurements of the EBL are hampered by foreground contamination, observations of VHE emission from distant sources can be used to obtain indirect measurements of the EBL. In this work a maximum-likelihood fit is applied to the energy spectra of blazars observed by VERITAS, an array of ground-based imaging atmospheric Cherenkov telescopes sensitive to very-high-energy (VHE; E>100 GeV) gamma rays. Using theoretical models of the EBL shape and intensity, the EBL normalization is treated as a free parameter, allowing for model-dependent constraints to be obtained. Details of this maximum-likelihood analysis and preliminary model-dependent constraints on the EBL, are presented., 8 pages, 4 figures, Proceedings of the 36th International Cosmic Ray Conference

Published
2019
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9. VERITAS Observations of 1ES 1218+304 during the 2019 VHE High State

Author

Stephan O'Brien

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Target of opportunity, FOS: Physical sciences, Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Blazar, Monitoring program, BL Lac object
Abstract

1ES 1218+304 is a moderate-redshift (z = 0.182) high-frequency-peaked BL Lac object (HBL). Detected by both the MAGIC and VERITAS gamma-ray observatories, 1ES 1218+304 is frequently monitored by VERITAS as part of its long-term blazar monitoring program. On the 3rd of January 2019, during a regularly scheduled blazar snapshot, VERITAS observed 1ES 1218+304 to have an elevated VHE flux state which continued through January 5 (ATEL #12360). In addition to VERITAS observations, MAGIC also detected elevated VHE emission (ATEL #12354) and Swift-BAT/XRT and Tuorla observations, in X-ray and optical respectively, showed increased multiwavelength activity at the time of the VERITAS observations. In this work, VERITAS observations of 1ES 1218+304 taken as part of a target of opportunity campaign during this elevated state, are presented., Comment: 8 pages, 3 figures, Proceedings of the 36th International Cosmic Ray Conference

Published
2019
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10. Combined Dark Matter searches towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, HESS, MAGIC and VERITAS

Author

Dirk Lennarz, Luis Villaseñor, Gernot Maier, Anne Lemiere, Daniel Rosa-Gonzalez, Samuel Timothy Spencer, Wystan Benbow, Victor Barbosa Martins, Raul Prado, Arache Djannati-Ataï, Regis Terrier, Dan Parsons, Francisco Salesa Greus, Dmitriy Kostunin, Joshua Wood, Carlo Romoli, César Alvarez, Carlo van Rensburg, Massimo Capasso, Sajan Kumar, P. Reichherzer, Anton Dmytriiev, Stefan Ohm, Chiara Giuri, Brian van Soelen, G. Peron, Christian Stegmann, Emma Ona-Wilhelmi, S. J. Fegan, Alison Peisker, Hawc, Garret Cotter, Gary Gillanders, Zhiqiu Huang, Krzysztof Katarzynski, Filiberto Hueyotl-Zahuantitla, Ian Herzog, D. A. Prokhorov, K. Kosack, Halim Ashkar, Fabian Leuschner, Manami Sasaki, Michael Schneider, Joe Lundeen, Markus Boettcher, Brian Humensky, Isak Delberth Davids, A. Fiasson, Stefan Wagner, Andreas Zech, Yasunobu Uchiyama, David Kieda, Michael DuVernois, Albert Seyffert, Gianluca Giavitto, Qi Feng, Andreas Specovius, Andrew James Smith, Catherine Boisson, L. Mohrmann, Roberta Zanin, Marek Jamrozy, Tomás Capistrán Rojas, K. Nakashima, Jamie Holder, Hao Zhou, Thomas Lohse, Mireia Nievas-Rosillo, Samuel Zouari, Ira Jung, Sebastian Panny, K. Bernloehr, Deivid Ribeiro, Andrea Santangelo, Kristi Engel, Josefa Becerra Gonzalez, Thomas Tavernier, Ke Fang, Rishi Babu, Yu Wun Wong, Gerd J. Kunde, Jean-Pierre Ernenwein, Henrike Fleischhack, P. T. O'Brien, Clemens Hoischen, A. A. Zdziarski, Kelly Malone, Helene Sol, Markus Holler, Manel Errando, Atreyee Sinha, Francois Brun, Heinrich J. Völk, Sumari Hattingh, Kirsten Tollefson, Johann van der Walt, Q. Remy, Felix Jankowsky, Samridha Kunwar, Johannes Veh, M. Fuessling, P. Vincent, Harm Schoorlemmer, Stefano Gabici, Miguel Mostafa, Tyler Williamson, Jacek Niemiec, Michal Ostrowski, J.-P. Lenain, Israel Martinez Castellanos, Felix Aharonian, Tadayuki Takahashi, Gerd Puehlhofer, Lei Sun, Jesús Martínez-Castro, Pooja Surajbali, Andrés Sandoval, Hugh Spackman, Takaaki Tanaka, Segev BenZvi, Alexandre Marcowith, Felix Werner, Olaf Reimer, Vincent Marandon, Alberto Carramiñana, S. Steinmassl, Mary Kertzman, Hannes Thiersen, Victor Doroshenko, Michael Backes, Hannah Jhee, G. Lamanna, Marcos Santander, Angel Noel, W. Jin, Gus Sinnis, B. Rudak, Alasdair E. Gent, Kathrin Egberts, Jonathan Mackey, Fernando Ureña-Mena, Paolo Marchegiani, Sonal Ramesh Patel, Laenita Lorraine Oberholzer, Tim Holch, Sami Caroff, Heiko Salzmann, E. Kasai, Alison Mitchell, Gregory Foote, Nukri Komin, Tom Armstrong, Michelle Hui, Ruo-Yu Shang, Binita Hona, Raquel Diaz Hernandez, Vardan Baghmanyan, Celine Armand, Alejandro Lara, David Berley, Hector Rueda Ricarte, Nissim Illich Fraija, Naomi Tsuji, Gaurang Yodh, Stefan Funk, Alicja Wierzcholska, Conor McGrath, Gerard Fontaine, C. Moore, Vikas Joshi, Dorit Glawion, T. Chand, M. U. Nisa, M.-H. Grondin, Arnaud Mares, David Sanchez, Ernesto Belmont-Moreno, Thomas Murach, Eucario Gonzalo Pérez Pérez, Paul Reynolds, Ignacio Taboada, Xiaojie Wang, Lucy Fortson, Martin Tluczykont, Thomas Brian Humensky, Juan de Dios Álvarez Romero, Robert Ellsworth, Hester Schutte, Justine Devin, Constantin Steppa, Richard White, Rachel Simoni, Karen S. Caballero Mora, Elisa Pueschel, Jason Fan, Tomasz Bulik, Lukas Nellen, Malgorzata Curlo, Lente Dreyer, J. Patrick Harding, Gilles Maurin, Humberto Martínez Huerta, Riaan Steenkamp, Arnulfo Zepeda, Johannes Schaefer, Werner Hofmann, Jim Hinton, Michael Punch, S. Sailer, Dmitry Khangulyan, Sergio Hernández Cadena, Charles Thorpe-Morgan, M. Hörbe, Stephan O'Brien, Ramin Marx, John L. Quinn, J. F. Glicenstein, V. Sahakian, M. Panter, Mora Durocher, U. Katz, Jacco Vink, Umberto Cotti, Tobias Kleiner, Petra Hüntemeyer, David Huber, Ullrich Schwanke, Diego Garcia Aguilar, Vladimir Vassiliev, Oscar Martinez, J. Bolmont, Cederik León de León, Brian Fick, Laura Olivera-Nieto, A. Yusafzai, David Hanna, James Buckley, Lorenzo Diaz, Yves Gallant, Guillermo García-Torales, Arun Babu Kollamparambil, James Ryan, Kayla Farrell, Sabrina Casanova, Bruno Khelifi, María Catalina Espinoza Hernández, Jorge Antonio Morales Soto, Mateo Fernandez Alonso, Matthew Lundy, Faical Ait-Benkhali, Jean Damascene Mbarubucyeye, Wlodek Kluzniak, Jorge Luis Flores, Ibrahim Torres, Jordan A. Goodman, Anita Reimer, Adam Otte, Eduardo Moreno Barbosa, M. J. Lang, Frank M. Rieger, Elijah Willox, Colin Adams, Pedro Miranda-Romagnoli, Louis Du Plessis, Andrea Albert, Orel Gueta, Anna Barnacka, Brenda Dingus, Gašper Kukec Mezek, Hazal Goksu, Jorge Cotzomi, William H. Lee, Ruben Alfaro, Glenn Sembroski, David A. Williams, Eduardo de la Fuente, Anu Kundu, Dezhi Huang, Brian Reville, Connor Duffy, Edna Ruiz-Velasco, Anna Luashvili, Alisha Chromey, Konstantin Pfrang, L. Giunti, Philip Kaaret, Maria Magdalena González, Olivier Hervet, Hermes Leon Vargas, Sébastien Le Stum, Amanda Weinstein, Aryeh Brill, James Davies, Ken Ragan, Santiago Pita, Juan Carlos Arteaga Velazquez, Jason Lee, Sabrina Einecke, Lukasz Stawarz, Iryna Lypova, Julie McEnery, Sara Coutiño de Leon, Dieter Horns, R. J. Tuffs, Christo Venter, Meghan Tanner, Monica Barnard, B. Bi, Yvonne Becherini, Colas Rivière, Iftach Sadeh, Lott Frans, Mischa Breuhaus, Pauline Chambery, C. Levy, Jose Luis García-Luna, Michelle Tsirou, D. Malyshev, Ramiro Torres Escobedo, Hassan Abdalla, Hambeleleni Ndiyavala, Chang Dong Rho, Jhilik Majumdar, Martin Pohl, Mathieu Bony, Oguzhan Anguener, Hend Yassin, Gwenael Giacinti, Manuel Meyer, Arturo Iriarte, John Matthews, Kirsty Feijen, Ahron S. Barber, Floriane Cangemi, Fernando Garfias, R. A. Ong, Thomas Weisgarber, Thomas Bylund, Gilgamesh Luis-Raya, Rowan Batzofin, Mathieu Naurois, Jacques Muller, Avery Archer, Andreas Quirrenbach, Anushka Udara Abeysekara, José Serna-Franco, Hugo Alberto Ayala Solares, Davit Zargaryan, Rubén López-Coto, Reshmi Mukherjee, Andreas Zmija, Guillem Marti'i-Devesa, Sameer Patel, M. Lemoine-Goumard, Roberto Noriega-Papaqui, Gaëtan Fichet de Clairfontaine, Axel Donath, A. W. Chen, Michael Kreter, Yunior Pérez Araujo, Anna Lia Longinotti, Michael Zacharias, Kleopas Shiningayamwe, Robert Brose, Fabian Schüssler, Emmanuel Moulin, Patrick Moriarty, Edna Ruiz Velasco, Michael Newbold, Oscar Chaparro-Amaro, J. T. Linnemann, Lenka Tomankova, Jodi Christiansen, Jaqueline Catalano, Ian James Watson, R. Konno, Andrew Taylor, C. Arcaro, Jason John Watson, Gavin Rowell, Daniel Omar Avila Rojas, Denys Malyshev, Emmet Roache, Rhiannon Turner, Chad Brisbois, Mohanraj Senniappan, José Roberto Angeles Camacho, Daniel Nieto, V. Poireau, Jimmy N.S. Shapopi, G. Vasileiadis, Hannah Dalgleish, donggeun tak, Juan Carlos Díaz Vélez, Armelle Jardin-Blicq, N. Zywucka, Abe Falcone, Nicola Omodei, Matthieu Renaud, German Hermann, Paul Morris, Maria Haupt, Stefan Klepser, Christopher van Eldik, Rafal Moderski, Alessandro Montanari, Amy Furniss, Sylvia Zhu, P. J. Meintjes, David Berge, Jose Andres Garcia-Gonzalez, Humberto Ibarguen Salazar, Wayne Robert Springer, Heike Prokoph, Marion Spir-Jacob, Amid Nayerhoda, Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Annecy de Physique des Particules (LAPP), Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS

Subjects
Cherenkov detector, air, Cherenkov counter: water, Physics beyond the Standard Model, Astrophysics::High Energy Astrophysical Phenomena, Dark matter, satellite, FOS: Physical sciences, IACT, Astrophysics, 01 natural sciences, GLAST, dark matter, law.invention, law, HESS, 0103 physical sciences, 010306 general physics, Cherenkov radiation, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Annihilation, 010308 nuclear & particles physics, background, new physics, imaging, sensitivity, MAGIC, Galaxy, Automatic Keywords, annihilation, VERITAS, galaxy, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], statistical, HAWC, Fermi Gamma-ray Space Telescope
Abstract

36th International Cosmic Ray Conference, ICRC2019, Madison, USA, 24 Jul 2019 - 1 Aug 2019; 9 pages (2019)., The search for Dark Matter (DM) has great potential to reveal physics beyond the Standard Model. As such, searches for evidence of DM particles are being carried out using a wide range of techniques, such as direct searches for DM particles, searches for DM produced with colliders, and indirect searches for the Standard Model annihilation products of DM. Dwarf spheroidal galaxies (dSphs) are excellent targets for indirect Dark Matter searches due to their relatively high DM content and negligible expected astrophysical background. A collaboration was formed to maximise the sensitivity of DM searches towards dSphs by combining for the first time dSph data from three imaging air Cherenkov telescope (IACT) arrays: HESS, MAGIC, and VERITAS; the Fermi-LAT satellite, and the water Cherenkov detector HAWC. Due to the diverse nature of the instruments involved, each experiment will analyse their individual datasets from multiple targets and then the results will be combined at the likelihood level. For consistency of the likelihoods across the five experiments, a common approach is used to treat the astrophysical factor (J-Factor) for each target and an agreed set of annihilation channels are considered. We also agree on a common statistical approach and treatment of instrumental systematic uncertainties. The results are presented in terms of constraints on the velocity-weighted cross section for DM self-annihilation as a function of the DM particle mass.

Published
2019
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11. Very high energy observations of the binaries V 404 CYG AND 4U 0115+634 during giant X-Ray outbursts

Author

Wystan Benbow, Daniel Nieto, D. Staszak, Sanjay Kumar, P. Kaaret, A. Flinders, K. Ragan, Gernot Maier, S. Griffin, Matteo Cerruti, I. Telezhinsky, David Kieda, Jamie Holder, S. P. Wakely, P. Moriarty, John L. Quinn, Karen Byrum, N. Kelley-Hoskins, R. Mukherjee, A. Furniss, T. B. Humensky, R. A. Ong, Wei Cui, E. Pueschel, M. Fernandez-Alonso, S. Schlenstedt, O. Hervet, Q. Feng, E. Roache, D. S. Hanna, P. Wilcox, M. P. Connolly, A. C. Rovero, N. H. Park, Gordon T. Richards, M. Kertzman, J. H. Buckley, Abraham D. Falcone, C. A. Johnson, V. Bugaev, Karlen Shahinyan, David A. Williams, E. Bourbeau, H. Fleischhack, Ralph Bird, T. T.Y. Lin, Julien Rousselle, P. T. Reynolds, I. Sadeh, M. Hütten, P. Kar, M. J. Lang, A. Popkow, J. Tyler, J. Grube, Manel Errando, A. Archer, Stephan O'Brien, G. H. Sembroski, Lucy Fortson, Martin Pohl, M. Buchovecky, J. P. Finley, Maria Krause, and A. Wilhelm

Subjects
transients, black-hole, Astrophysics::High Energy Astrophysical Phenomena, Ciencias Físicas, X-ray binary, Flux, FOS: Physical sciences, Astrophysics, stars: individual (v 404 cyg, 4u 0115+634), 01 natural sciences, VERY HIGH ENERGY GAMMA RAYS, Luminosity, spectrum, X-RAY TRANSIENTS, purl.org/becyt/ford/1 [https], symbols.namesake, Observatory, 0103 physical sciences, Binary star, emission, tev, 010306 general physics, 010303 astronomy & astrophysics, acceleration of particles, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), ls i+61-degrees 303, Gamma ray, v404 cygni, Astronomy and Astrophysics, gamma rays: general, purl.org/becyt/ford/1.3 [https], veritas observations, Astronomía, Stars, binaries: general, 13. Climate action, Space and Planetary Science, Eddington luminosity, symbols, ddc:520, Astrophysics - High Energy Astrophysical Phenomena, CIENCIAS NATURALES Y EXACTAS, BINARY STARS
Abstract

Transient X-ray binaries produce major outbursts in which the X-ray flux can increase over the quiescent level by factors as large as $10^7$. The low-mass X-ray binary V 404 Cyg and the high-mass system 4U 0115+634 underwent such major outbursts in June and October 2015, respectively. We present here observations at energies above hundreds of GeV with the VERITAS observatory taken during some of the brightest X-ray activity ever observed from these systems. No gamma-ray emission has been detected by VERITAS in 2.5 hours of observations of the microquasar V 404 Cyg from 2015, June 20-21. The upper flux limits derived from these observations on the gamma-ray flux above 200 GeV of F $< 4.4\times 10^{-12}$ cm$^{-2}$ s$^{-1}$ correspond to a tiny fraction (about $10^{-6}$) of the Eddington luminosity of the system, in stark contrast to that seen in the X-ray band. No gamma rays have been detected during observations of 4U 0115+634 in the period of major X-ray activity in October 2015. The flux upper limit derived from our observations is F $< 2.1\times 10^{-12}$ cm$^{-2}$ s$^{-1}$ for gamma rays above 300 GeV, setting an upper limit on the ratio of gamma-ray to X-ray luminosity of less than 4%., Accepted for publication in the Astrophysical Journal

Published
2016
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12. Matching 3D segmented objects using wire frame analysis

Author

Stephan O'Brien and Charles R. Allen

Subjects
Matching (graph theory), business.industry, Machine vision, Computer science, Transputer, Perspective (graphical), ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, 3D modeling, Software, Computer graphics (images), 3-dimensional matching, Computer vision, Artificial intelligence, business, Vertical circle
Abstract

This paper describes a novel technique in 3D sensory fusion for autonomous mobile vehicles. The primary sensor is a monocular camera mounted on a robot manipulator which pans to up to three positions on a 0.5 m vertical circle, while mounted on the mobile vehicle. The passive scene is analyzed using a method of inverse perspective, which is described and the resulting scene analysis comprises 3D wire frames of all surfaces detected in 3D. The 3D scene analysis uses a dual T-800 transputer based multiprocessor which cycles through generating primary scene information at rates of 1 update per 10 seconds. A PC-based 3D matching algorithm is then used to match the segmented objects to a database of pre-taught 3D wire frames. The matching software is written in Prolog.

Published
1993
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