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Your search keyword '"PLEWA, PHILIPP M."' showing total 12 results
Start Over Author "PLEWA, PHILIPP M." Publication Type Electronic Resources
12 results on '"PLEWA, PHILIPP M."'

1. A Detection of Sgr A* in the far infrared

Author

von Fellenberg, Sebastiano D., Gillessen, Stefan, Graciá-Carpio, Javier, Fritz, Tobias K., Dexter, Jason, Bauböck, Michi, Ponti, Gabriele, Gao, Feng, Habibi, Maryam, Plewa, Philipp M., Pfuhl, Oliver, Jimenez-Rosales, Alejandra, Waisberg, Idel, Widmann, Felix, Ott, Thomas, Eisenhauer, Frank, Genzel, Reinhard, von Fellenberg, Sebastiano D., Gillessen, Stefan, Graciá-Carpio, Javier, Fritz, Tobias K., Dexter, Jason, Bauböck, Michi, Ponti, Gabriele, Gao, Feng, Habibi, Maryam, Plewa, Philipp M., Pfuhl, Oliver, Jimenez-Rosales, Alejandra, Waisberg, Idel, Widmann, Felix, Ott, Thomas, Eisenhauer, Frank, and Genzel, Reinhard

Abstract

We report the first detection of the Galactic Centre massive black hole, Sgr~A*, in the far infrared. Our measurements were obtained with PACS on board the \emph{Herschel} satellite at $100~\mathrm{\mu m}$ and $160~\mathrm{\mu m}$. While the warm dust in the Galactic Centre is too bright to allow for a direct detection of Sgr~A*, we measure a significant and simultaneous variation of its flux of $\Delta F_{\nu\widehat{=}160 ~\mathrm{\mu m}} = (0.27\pm0.06)~\mathrm{Jy}$ and $\Delta F_{\nu\widehat{=}100 ~\mathrm{\mu m}}= (0.16\pm0.10)~\mathrm{Jy}$ during one observation. The significance level of the $160 ~\mathrm{\mu m}$ band variability is $4.5\sigma$ and the corresponding $100 ~\mathrm{\mu m}$ band variability is significant at $1.6\sigma$. We find no example of an equally significant false positive detection. Conservatively assuming a variability of $25\%$ in the FIR, we can provide upper limits to the flux. Comparing the latter with theoretical models we find that 1D RIAF models have difficulties explaining the observed faintness. However, the upper limits are consistent with modern ALMA and VLA observations. Our upper limits provide further evidence for a spectral peak at $\sim 10^{12} ~ \mathrm{Hz}$ and constrain the number density of $\gamma \sim 100$ electrons in the accretion disk and or outflow., Comment: accepted for publication in APJ

Published
2018
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2. Multiple Star Systems in the Orion Nebula

Author

GRAVITY collaboration, Karl, Martina, Pfuhl, Oliver, Eisenhauer, Frank, Genzel, Reinhard, Grellmann, Rebekka, Habibi, Maryam, Abuter, Roberto, Accardo, Matteo, Amorim, António, Anugu, Narsireddy, Ávila, Gerardo, Benisty, Myriam, Berger, Jean-Philippe, Bland, Nicolas, Bonnet, Henri, Bourget, Pierre, Brandner, Wolfgang, Brast, Roland, Buron, Alexander, Garatti, Alessio Caratti o, Chapron, Frédéric, Clénet, Yann, Collin, Claude, Foresto, Vincent Coudé du, de Wit, Willem-Jan, de Zeeuw, Tim, Deen, Casey, Delplancke-Ströbele, Françoise, Dembet, Roderick, Derie, Frédéric, Dexter, Jason, Duvert, Gilles, Ebert, Monica, Eckart, Andreas, Esselborn, Michael, Fédou, Pierre, Finger, Gert, Garcia, Paulo, Dabo, Cesar Enrique Garcia, Lopez, Rebeca Garcia, Gao, Feng, Gandron, Éric, Gillessen, Stefan, Gonté, Frédéric, Gordo, Paulo, Grözinger, Ulrich, Guajardo, Patricia, Guieu, Sylvain, Haguenauer, Pierre, Hans, Oliver, Haubois, Xavier, Haug, Marcus, Haußmann, Frank, Henning, Thomas, Hippler, Stefan, Horrobin, Matthew, Huber, Armin, Hubert, Zoltan, Hubin, Norbert, Hummel, Christian A., Jakob, Gerd, Jochum, Lieselotte, Jocou, Laurent, Kaufer, Andreas, Kellner, Stefan, Kandrew, Sarah, Kern, Lothar, Kervella, Pierre, Kiekebusch, Mario, Klein, Ralf, Köhler, Rainer, Kolb, Johan, Kulas, Martin, Lacour, Sylvestre, Lapeyrère, Vincent, Lazareff, Bernard, Bouquin, Jean-Baptiste Le, Léna, Pierre, Lenzen, Rainer, Lévêque, Samuel, Lin, Chien-Cheng, Lippa, Magdalena, Magnard, Yves, Mehrgan, Leander, Mérand, Antoine, Moulin, Thibaut, Müller, Eric, Müller, Friedrich, Neumann, Udo, Oberti, Sylvain, Ott, Thomas, Pallanca, Laurent, Panduro, Johana, Pasquini, Luca, Paumard, Thibaut, Percheron, Isabelle, Perraut, Karine, Perrin, Guy, Pflüger, Andreas, Duc, Thanh Phan, Plewa, Philipp M., Popovic, Dan, Rabien, Sebastian, Ramírez, Andrés, Ramos, Jose, Rau, Christian, Riquelme, Miguel, Rodríguez-Coira, Gustavo, Rohloff, Ralf-Rainer, Rosales, Alejandra, Rousset, Gérard, Sanchez-Bermudez, Joel, Scheithauer, Silvia, Schöller, Markus, Schuhler, Nicolas, Spyromilio, Jason, Straub, Odele, Straubmeier, Christian, Sturm, Eckhard, Suarez, Marcos, Tristram, Konrad R. W., Ventura, Noel, Vincent, Frédéric, Waisberg, Idel, Wank, Imke, Widmann, Felix, Wieprecht, Ekkehard, Wiest, Michael, Wiezorrek, Erich, Wittkowski, Markus, Woillez, Julien, Wolff, Burkhard, Yazici, Senol, Ziegler, Denis, Zins, Gérard, GRAVITY collaboration, Karl, Martina, Pfuhl, Oliver, Eisenhauer, Frank, Genzel, Reinhard, Grellmann, Rebekka, Habibi, Maryam, Abuter, Roberto, Accardo, Matteo, Amorim, António, Anugu, Narsireddy, Ávila, Gerardo, Benisty, Myriam, Berger, Jean-Philippe, Bland, Nicolas, Bonnet, Henri, Bourget, Pierre, Brandner, Wolfgang, Brast, Roland, Buron, Alexander, Garatti, Alessio Caratti o, Chapron, Frédéric, Clénet, Yann, Collin, Claude, Foresto, Vincent Coudé du, de Wit, Willem-Jan, de Zeeuw, Tim, Deen, Casey, Delplancke-Ströbele, Françoise, Dembet, Roderick, Derie, Frédéric, Dexter, Jason, Duvert, Gilles, Ebert, Monica, Eckart, Andreas, Esselborn, Michael, Fédou, Pierre, Finger, Gert, Garcia, Paulo, Dabo, Cesar Enrique Garcia, Lopez, Rebeca Garcia, Gao, Feng, Gandron, Éric, Gillessen, Stefan, Gonté, Frédéric, Gordo, Paulo, Grözinger, Ulrich, Guajardo, Patricia, Guieu, Sylvain, Haguenauer, Pierre, Hans, Oliver, Haubois, Xavier, Haug, Marcus, Haußmann, Frank, Henning, Thomas, Hippler, Stefan, Horrobin, Matthew, Huber, Armin, Hubert, Zoltan, Hubin, Norbert, Hummel, Christian A., Jakob, Gerd, Jochum, Lieselotte, Jocou, Laurent, Kaufer, Andreas, Kellner, Stefan, Kandrew, Sarah, Kern, Lothar, Kervella, Pierre, Kiekebusch, Mario, Klein, Ralf, Köhler, Rainer, Kolb, Johan, Kulas, Martin, Lacour, Sylvestre, Lapeyrère, Vincent, Lazareff, Bernard, Bouquin, Jean-Baptiste Le, Léna, Pierre, Lenzen, Rainer, Lévêque, Samuel, Lin, Chien-Cheng, Lippa, Magdalena, Magnard, Yves, Mehrgan, Leander, Mérand, Antoine, Moulin, Thibaut, Müller, Eric, Müller, Friedrich, Neumann, Udo, Oberti, Sylvain, Ott, Thomas, Pallanca, Laurent, Panduro, Johana, Pasquini, Luca, Paumard, Thibaut, Percheron, Isabelle, Perraut, Karine, Perrin, Guy, Pflüger, Andreas, Duc, Thanh Phan, Plewa, Philipp M., Popovic, Dan, Rabien, Sebastian, Ramírez, Andrés, Ramos, Jose, Rau, Christian, Riquelme, Miguel, Rodríguez-Coira, Gustavo, Rohloff, Ralf-Rainer, Rosales, Alejandra, Rousset, Gérard, Sanchez-Bermudez, Joel, Scheithauer, Silvia, Schöller, Markus, Schuhler, Nicolas, Spyromilio, Jason, Straub, Odele, Straubmeier, Christian, Sturm, Eckhard, Suarez, Marcos, Tristram, Konrad R. W., Ventura, Noel, Vincent, Frédéric, Waisberg, Idel, Wank, Imke, Widmann, Felix, Wieprecht, Ekkehard, Wiest, Michael, Wiezorrek, Erich, Wittkowski, Markus, Woillez, Julien, Wolff, Burkhard, Yazici, Senol, Ziegler, Denis, and Zins, Gérard

Abstract

This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium Cluster with the recently comissioned GRAVITY instrument. We observe a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for $\theta ^1$ Ori B, $\theta ^2$ Ori B, and $\theta ^2$ Ori C. We determine a separation for the previously suspected companion of NU Ori. We confirm four companions for $\theta ^1$ Ori A, $\theta ^1$ Ori C, $\theta ^1$ Ori D, and $\theta ^2$ Ori A, all with substantially improved astrometry and photometric mass estimates. We refine the orbit of the eccentric high-mass binary $\theta ^1$ Ori C and we are able to derive a new orbit for $\theta ^1$ Ori D. We find a system mass of 21.7 $M_{\odot}$ and a period of $53$ days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about 2, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints towards a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We exclude collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion., Comment: Accepted for publication in A&A

Published
2018
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3. Ionized and molecular gas kinematics in a z=1.4 star-forming galaxy

Author

Übler, Hannah D. N., Genzel, Reinhard, Tacconi, Linda J., Schreiber, Natascha M. Förster, Neri, Roberto, Contursi, Alessandra, Belli, Sirio, Nelson, Erica J., Lang, Philipp, Shimizu, T. Taro, Davies, Ric, Herrera-Camus, Rodrigo, Lutz, Dieter, Plewa, Philipp M., Price, Sedona H., Schuster, Karl, Sternberg, Amiel, Tadaki, Ken-ichi, Wisnioski, Emily, Wuyts, Stijn, Übler, Hannah D. N., Genzel, Reinhard, Tacconi, Linda J., Schreiber, Natascha M. Förster, Neri, Roberto, Contursi, Alessandra, Belli, Sirio, Nelson, Erica J., Lang, Philipp, Shimizu, T. Taro, Davies, Ric, Herrera-Camus, Rodrigo, Lutz, Dieter, Plewa, Philipp M., Price, Sedona H., Schuster, Karl, Sternberg, Amiel, Tadaki, Ken-ichi, Wisnioski, Emily, and Wuyts, Stijn

Abstract

We present deep observations of a $z=1.4$ massive, star-forming galaxy in molecular and ionized gas at comparable spatial resolution (CO 3-2, NOEMA; H$\alpha$, LBT). The kinematic tracers agree well, indicating that both gas phases are subject to the same gravitational potential and physical processes affecting the gas dynamics. We combine the one-dimensional velocity and velocity dispersion profiles in CO and H$\alpha$ to forward-model the galaxy in a Bayesian framework, combining a thick exponential disk, a bulge, and a dark matter halo. We determine the dynamical support due to baryons and dark matter, and find a dark matter fraction within one effective radius of $f_{\rm DM}(\leq$$R_{e})=0.18^{+0.06}_{-0.04}$. Our result strengthens the evidence for strong baryon-dominance on galactic scales of massive $z\sim1-3$ star-forming galaxies recently found based on ionized gas kinematics alone., Comment: accepted for publication in the Astrophysical Journal Letters

Published
2018
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4. Multiple star systems in the Orion nebula

Author

Karl, Martina, Pfuhl, Oliver, Eisenhauer, Frank, Genzel, Reinhard, Grellmann, Rebekka, Habibi, Maryam, Abuter, Roberto, Accardo, Matteo, Amorim, Antonio, Anugu, Narsireddy, Avila, Gerardo, Benisty, Myriam, Berger, Jean-Philippe, Blind, Nicolas, Bonnet, Henri, Bourget, Pierre, Brandner, Wolfgang, Brast, Roland, Buron, Alexander, Garatti, Alessio Caratti O., Chapron, Frederic, Clenet, Yann, Collin, Claude, du Foresto, Vincent Coude, de Wit, Willem-Jan, de Zeeuw, Tim, Deen, Casey, Delplancke-Stroebele, Francoise, Dembet, Roderick, Derie, Frederic, Dexter, Jason, Duvert, Gilles, Ebert, Monica, Eckart, Andreas, Esselborn, Michael, Fedou, Pierre, Finger, Gert, Garcia, Paulo, Dabo, Cesar Enrique Garcia, Lopez, Rebeca Garcia, Gao, Feng, Gendron, Eric, Gillessen, Stefan, Gonte, Frederic, Gordo, Paulo, Groezinger, Ulrich, Guajardo, Patricia, Guieu, Sylvain, Haguenauer, Pierre, Hans, Oliver, Haubois, Xavier, Haug, Marcus, Haussmann, Frank, Henning, Thomas, Hippler, Stefan, Horrobin, Matthew, Huber, Armin, Hubert, Zoltan, Hubin, Norbert, Jakob, Gerd, Jochum, Lieselotte, Jocou, Laurent, Kaufer, Andreas, Kellner, Stefan, Kendrew, Sarah, Kern, Lothar, Kervella, Pierre, Kiekebusch, Mario, Klein, Ralf, Koehler, Rainer, Kolb, Johan, Kulas, Martin, Lacour, Sylvestre, Lapeyrere, Vincent, Lazareff, Bernard, Le Bouquin, Jean-Baptiste, Lena, Pierre, Lenzen, Rainer, Leveque, Samuel, Lin, Chien-Cheng, Lippa, Magdalena, Magnard, Yves, Mehrgan, Leander, Merand, Antoine, Moulin, Thibaut, Mueller, Eric, Mueller, Friedrich, Neumann, Udo, Oberti, Sylvain, Ott, Thomas, Pallanca, Laurent, Panduro, Johana, Pasquini, Luca, Paumard, Thibaut, Percheron, Isabelle, Perraut, Karine, Perrin, Guy, Pflueger, Andreas, Plewa, Philipp M., Popovic, Dan, Rabien, Sebastian, Ramirez, Andres, Ramos, Jose, Rau, Christian, Riquelme, Miguel, Rodriguez-Coira, Gustavo, Rohloff, Ralf-Rainer, Rosales, Alejandra, Rousset, Gerard, Sanchez-Bermudez, Joel, Scheithauer, Silvia, Schoeller, Markus, Schuhler, Nicolas, Spyromilio, Jason, Straub, Odele, Straubmeier, Christian, Sturm, Eckhard, Suarez, Marcos, Tristram, Konrad R. W., Ventura, Noel, Vincent, Frederic, Waisberg, Idel, Wank, Imke, Widmann, Felix, Wieprecht, Ekkehard, Wiest, Michael, Wiezorrek, Erich, Wittkowski, Markus, Woillez, Julien, Wolff, Burkhard, Yazici, Senol, Ziegler, Denis, Zins, Gerard, Karl, Martina, Pfuhl, Oliver, Eisenhauer, Frank, Genzel, Reinhard, Grellmann, Rebekka, Habibi, Maryam, Abuter, Roberto, Accardo, Matteo, Amorim, Antonio, Anugu, Narsireddy, Avila, Gerardo, Benisty, Myriam, Berger, Jean-Philippe, Blind, Nicolas, Bonnet, Henri, Bourget, Pierre, Brandner, Wolfgang, Brast, Roland, Buron, Alexander, Garatti, Alessio Caratti O., Chapron, Frederic, Clenet, Yann, Collin, Claude, du Foresto, Vincent Coude, de Wit, Willem-Jan, de Zeeuw, Tim, Deen, Casey, Delplancke-Stroebele, Francoise, Dembet, Roderick, Derie, Frederic, Dexter, Jason, Duvert, Gilles, Ebert, Monica, Eckart, Andreas, Esselborn, Michael, Fedou, Pierre, Finger, Gert, Garcia, Paulo, Dabo, Cesar Enrique Garcia, Lopez, Rebeca Garcia, Gao, Feng, Gendron, Eric, Gillessen, Stefan, Gonte, Frederic, Gordo, Paulo, Groezinger, Ulrich, Guajardo, Patricia, Guieu, Sylvain, Haguenauer, Pierre, Hans, Oliver, Haubois, Xavier, Haug, Marcus, Haussmann, Frank, Henning, Thomas, Hippler, Stefan, Horrobin, Matthew, Huber, Armin, Hubert, Zoltan, Hubin, Norbert, Jakob, Gerd, Jochum, Lieselotte, Jocou, Laurent, Kaufer, Andreas, Kellner, Stefan, Kendrew, Sarah, Kern, Lothar, Kervella, Pierre, Kiekebusch, Mario, Klein, Ralf, Koehler, Rainer, Kolb, Johan, Kulas, Martin, Lacour, Sylvestre, Lapeyrere, Vincent, Lazareff, Bernard, Le Bouquin, Jean-Baptiste, Lena, Pierre, Lenzen, Rainer, Leveque, Samuel, Lin, Chien-Cheng, Lippa, Magdalena, Magnard, Yves, Mehrgan, Leander, Merand, Antoine, Moulin, Thibaut, Mueller, Eric, Mueller, Friedrich, Neumann, Udo, Oberti, Sylvain, Ott, Thomas, Pallanca, Laurent, Panduro, Johana, Pasquini, Luca, Paumard, Thibaut, Percheron, Isabelle, Perraut, Karine, Perrin, Guy, Pflueger, Andreas, Plewa, Philipp M., Popovic, Dan, Rabien, Sebastian, Ramirez, Andres, Ramos, Jose, Rau, Christian, Riquelme, Miguel, Rodriguez-Coira, Gustavo, Rohloff, Ralf-Rainer, Rosales, Alejandra, Rousset, Gerard, Sanchez-Bermudez, Joel, Scheithauer, Silvia, Schoeller, Markus, Schuhler, Nicolas, Spyromilio, Jason, Straub, Odele, Straubmeier, Christian, Sturm, Eckhard, Suarez, Marcos, Tristram, Konrad R. W., Ventura, Noel, Vincent, Frederic, Waisberg, Idel, Wank, Imke, Widmann, Felix, Wieprecht, Ekkehard, Wiest, Michael, Wiezorrek, Erich, Wittkowski, Markus, Woillez, Julien, Wolff, Burkhard, Yazici, Senol, Ziegler, Denis, and Zins, Gerard

Abstract

This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium cluster with the recently comissioned GRAVITY instrument. We observed a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for theta(1) Ori B, theta(2) Ori B, and theta(2) Ori C. We determined a separation for the previously suspected companion of NU Ori. We confirm four companions for theta(1) Ori A, theta(1) Ori C, theta(1) Ori D, and theta(2) Ori A, all with substantially improved astrometry and photometric mass estimates. We refined the orbit of the eccentric high-mass binary theta(1) Ori C and we are able to derive a new orbit for theta(1) Ori D. We find a system mass of 21.7 M-circle dot and a period of 53 days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about two, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints toward a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We excluded collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion.

Published
2018

5. Multiple star systems in the Orion nebula

Author

Karl, Martina, Pfuhl, Oliver, Eisenhauer, Frank, Genzel, Reinhard, Grellmann, Rebekka, Habibi, Maryam, Abuter, Roberto, Accardo, Matteo, Amorim, Antonio, Anugu, Narsireddy, Avila, Gerardo, Benisty, Myriam, Berger, Jean-Philippe, Blind, Nicolas, Bonnet, Henri, Bourget, Pierre, Brandner, Wolfgang, Brast, Roland, Buron, Alexander, Garatti, Alessio Caratti O., Chapron, Frederic, Clenet, Yann, Collin, Claude, du Foresto, Vincent Coude, de Wit, Willem-Jan, de Zeeuw, Tim, Deen, Casey, Delplancke-Stroebele, Francoise, Dembet, Roderick, Derie, Frederic, Dexter, Jason, Duvert, Gilles, Ebert, Monica, Eckart, Andreas, Esselborn, Michael, Fedou, Pierre, Finger, Gert, Garcia, Paulo, Dabo, Cesar Enrique Garcia, Lopez, Rebeca Garcia, Gao, Feng, Gendron, Eric, Gillessen, Stefan, Gonte, Frederic, Gordo, Paulo, Groezinger, Ulrich, Guajardo, Patricia, Guieu, Sylvain, Haguenauer, Pierre, Hans, Oliver, Haubois, Xavier, Haug, Marcus, Haussmann, Frank, Henning, Thomas, Hippler, Stefan, Horrobin, Matthew, Huber, Armin, Hubert, Zoltan, Hubin, Norbert, Jakob, Gerd, Jochum, Lieselotte, Jocou, Laurent, Kaufer, Andreas, Kellner, Stefan, Kendrew, Sarah, Kern, Lothar, Kervella, Pierre, Kiekebusch, Mario, Klein, Ralf, Koehler, Rainer, Kolb, Johan, Kulas, Martin, Lacour, Sylvestre, Lapeyrere, Vincent, Lazareff, Bernard, Le Bouquin, Jean-Baptiste, Lena, Pierre, Lenzen, Rainer, Leveque, Samuel, Lin, Chien-Cheng, Lippa, Magdalena, Magnard, Yves, Mehrgan, Leander, Merand, Antoine, Moulin, Thibaut, Mueller, Eric, Mueller, Friedrich, Neumann, Udo, Oberti, Sylvain, Ott, Thomas, Pallanca, Laurent, Panduro, Johana, Pasquini, Luca, Paumard, Thibaut, Percheron, Isabelle, Perraut, Karine, Perrin, Guy, Pflueger, Andreas, Plewa, Philipp M., Popovic, Dan, Rabien, Sebastian, Ramirez, Andres, Ramos, Jose, Rau, Christian, Riquelme, Miguel, Rodriguez-Coira, Gustavo, Rohloff, Ralf-Rainer, Rosales, Alejandra, Rousset, Gerard, Sanchez-Bermudez, Joel, Scheithauer, Silvia, Schoeller, Markus, Schuhler, Nicolas, Spyromilio, Jason, Straub, Odele, Straubmeier, Christian, Sturm, Eckhard, Suarez, Marcos, Tristram, Konrad R. W., Ventura, Noel, Vincent, Frederic, Waisberg, Idel, Wank, Imke, Widmann, Felix, Wieprecht, Ekkehard, Wiest, Michael, Wiezorrek, Erich, Wittkowski, Markus, Woillez, Julien, Wolff, Burkhard, Yazici, Senol, Ziegler, Denis, Zins, Gerard, Karl, Martina, Pfuhl, Oliver, Eisenhauer, Frank, Genzel, Reinhard, Grellmann, Rebekka, Habibi, Maryam, Abuter, Roberto, Accardo, Matteo, Amorim, Antonio, Anugu, Narsireddy, Avila, Gerardo, Benisty, Myriam, Berger, Jean-Philippe, Blind, Nicolas, Bonnet, Henri, Bourget, Pierre, Brandner, Wolfgang, Brast, Roland, Buron, Alexander, Garatti, Alessio Caratti O., Chapron, Frederic, Clenet, Yann, Collin, Claude, du Foresto, Vincent Coude, de Wit, Willem-Jan, de Zeeuw, Tim, Deen, Casey, Delplancke-Stroebele, Francoise, Dembet, Roderick, Derie, Frederic, Dexter, Jason, Duvert, Gilles, Ebert, Monica, Eckart, Andreas, Esselborn, Michael, Fedou, Pierre, Finger, Gert, Garcia, Paulo, Dabo, Cesar Enrique Garcia, Lopez, Rebeca Garcia, Gao, Feng, Gendron, Eric, Gillessen, Stefan, Gonte, Frederic, Gordo, Paulo, Groezinger, Ulrich, Guajardo, Patricia, Guieu, Sylvain, Haguenauer, Pierre, Hans, Oliver, Haubois, Xavier, Haug, Marcus, Haussmann, Frank, Henning, Thomas, Hippler, Stefan, Horrobin, Matthew, Huber, Armin, Hubert, Zoltan, Hubin, Norbert, Jakob, Gerd, Jochum, Lieselotte, Jocou, Laurent, Kaufer, Andreas, Kellner, Stefan, Kendrew, Sarah, Kern, Lothar, Kervella, Pierre, Kiekebusch, Mario, Klein, Ralf, Koehler, Rainer, Kolb, Johan, Kulas, Martin, Lacour, Sylvestre, Lapeyrere, Vincent, Lazareff, Bernard, Le Bouquin, Jean-Baptiste, Lena, Pierre, Lenzen, Rainer, Leveque, Samuel, Lin, Chien-Cheng, Lippa, Magdalena, Magnard, Yves, Mehrgan, Leander, Merand, Antoine, Moulin, Thibaut, Mueller, Eric, Mueller, Friedrich, Neumann, Udo, Oberti, Sylvain, Ott, Thomas, Pallanca, Laurent, Panduro, Johana, Pasquini, Luca, Paumard, Thibaut, Percheron, Isabelle, Perraut, Karine, Perrin, Guy, Pflueger, Andreas, Plewa, Philipp M., Popovic, Dan, Rabien, Sebastian, Ramirez, Andres, Ramos, Jose, Rau, Christian, Riquelme, Miguel, Rodriguez-Coira, Gustavo, Rohloff, Ralf-Rainer, Rosales, Alejandra, Rousset, Gerard, Sanchez-Bermudez, Joel, Scheithauer, Silvia, Schoeller, Markus, Schuhler, Nicolas, Spyromilio, Jason, Straub, Odele, Straubmeier, Christian, Sturm, Eckhard, Suarez, Marcos, Tristram, Konrad R. W., Ventura, Noel, Vincent, Frederic, Waisberg, Idel, Wank, Imke, Widmann, Felix, Wieprecht, Ekkehard, Wiest, Michael, Wiezorrek, Erich, Wittkowski, Markus, Woillez, Julien, Wolff, Burkhard, Yazici, Senol, Ziegler, Denis, and Zins, Gerard

Abstract

This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium cluster with the recently comissioned GRAVITY instrument. We observed a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for theta(1) Ori B, theta(2) Ori B, and theta(2) Ori C. We determined a separation for the previously suspected companion of NU Ori. We confirm four companions for theta(1) Ori A, theta(1) Ori C, theta(1) Ori D, and theta(2) Ori A, all with substantially improved astrometry and photometric mass estimates. We refined the orbit of the eccentric high-mass binary theta(1) Ori C and we are able to derive a new orbit for theta(1) Ori D. We find a system mass of 21.7 M-circle dot and a period of 53 days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about two, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints toward a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We excluded collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion.

Published
2018

6. Multiple Star Systems in the Orion Nebula

Author

GRAVITY collaboration, Karl, Martina, Pfuhl, Oliver, Eisenhauer, Frank, Genzel, Reinhard, Grellmann, Rebekka, Habibi, Maryam, Abuter, Roberto, Accardo, Matteo, Amorim, António, Anugu, Narsireddy, Ávila, Gerardo, Benisty, Myriam, Berger, Jean-Philippe, Bland, Nicolas, Bonnet, Henri, Bourget, Pierre, Brandner, Wolfgang, Brast, Roland, Buron, Alexander, Garatti, Alessio Caratti o, Chapron, Frédéric, Clénet, Yann, Collin, Claude, Foresto, Vincent Coudé du, de Wit, Willem-Jan, de Zeeuw, Tim, Deen, Casey, Delplancke-Ströbele, Françoise, Dembet, Roderick, Derie, Frédéric, Dexter, Jason, Duvert, Gilles, Ebert, Monica, Eckart, Andreas, Esselborn, Michael, Fédou, Pierre, Finger, Gert, Garcia, Paulo, Dabo, Cesar Enrique Garcia, Lopez, Rebeca Garcia, Gao, Feng, Gandron, Éric, Gillessen, Stefan, Gonté, Frédéric, Gordo, Paulo, Grözinger, Ulrich, Guajardo, Patricia, Guieu, Sylvain, Haguenauer, Pierre, Hans, Oliver, Haubois, Xavier, Haug, Marcus, Haußmann, Frank, Henning, Thomas, Hippler, Stefan, Horrobin, Matthew, Huber, Armin, Hubert, Zoltan, Hubin, Norbert, Hummel, Christian A., Jakob, Gerd, Jochum, Lieselotte, Jocou, Laurent, Kaufer, Andreas, Kellner, Stefan, Kandrew, Sarah, Kern, Lothar, Kervella, Pierre, Kiekebusch, Mario, Klein, Ralf, Köhler, Rainer, Kolb, Johan, Kulas, Martin, Lacour, Sylvestre, Lapeyrère, Vincent, Lazareff, Bernard, Bouquin, Jean-Baptiste Le, Léna, Pierre, Lenzen, Rainer, Lévêque, Samuel, Lin, Chien-Cheng, Lippa, Magdalena, Magnard, Yves, Mehrgan, Leander, Mérand, Antoine, Moulin, Thibaut, Müller, Eric, Müller, Friedrich, Neumann, Udo, Oberti, Sylvain, Ott, Thomas, Pallanca, Laurent, Panduro, Johana, Pasquini, Luca, Paumard, Thibaut, Percheron, Isabelle, Perraut, Karine, Perrin, Guy, Pflüger, Andreas, Duc, Thanh Phan, Plewa, Philipp M., Popovic, Dan, Rabien, Sebastian, Ramírez, Andrés, Ramos, Jose, Rau, Christian, Riquelme, Miguel, Rodríguez-Coira, Gustavo, Rohloff, Ralf-Rainer, Rosales, Alejandra, Rousset, Gérard, Sanchez-Bermudez, Joel, Scheithauer, Silvia, Schöller, Markus, Schuhler, Nicolas, Spyromilio, Jason, Straub, Odele, Straubmeier, Christian, Sturm, Eckhard, Suarez, Marcos, Tristram, Konrad R. W., Ventura, Noel, Vincent, Frédéric, Waisberg, Idel, Wank, Imke, Widmann, Felix, Wieprecht, Ekkehard, Wiest, Michael, Wiezorrek, Erich, Wittkowski, Markus, Woillez, Julien, Wolff, Burkhard, Yazici, Senol, Ziegler, Denis, Zins, Gérard, GRAVITY collaboration, Karl, Martina, Pfuhl, Oliver, Eisenhauer, Frank, Genzel, Reinhard, Grellmann, Rebekka, Habibi, Maryam, Abuter, Roberto, Accardo, Matteo, Amorim, António, Anugu, Narsireddy, Ávila, Gerardo, Benisty, Myriam, Berger, Jean-Philippe, Bland, Nicolas, Bonnet, Henri, Bourget, Pierre, Brandner, Wolfgang, Brast, Roland, Buron, Alexander, Garatti, Alessio Caratti o, Chapron, Frédéric, Clénet, Yann, Collin, Claude, Foresto, Vincent Coudé du, de Wit, Willem-Jan, de Zeeuw, Tim, Deen, Casey, Delplancke-Ströbele, Françoise, Dembet, Roderick, Derie, Frédéric, Dexter, Jason, Duvert, Gilles, Ebert, Monica, Eckart, Andreas, Esselborn, Michael, Fédou, Pierre, Finger, Gert, Garcia, Paulo, Dabo, Cesar Enrique Garcia, Lopez, Rebeca Garcia, Gao, Feng, Gandron, Éric, Gillessen, Stefan, Gonté, Frédéric, Gordo, Paulo, Grözinger, Ulrich, Guajardo, Patricia, Guieu, Sylvain, Haguenauer, Pierre, Hans, Oliver, Haubois, Xavier, Haug, Marcus, Haußmann, Frank, Henning, Thomas, Hippler, Stefan, Horrobin, Matthew, Huber, Armin, Hubert, Zoltan, Hubin, Norbert, Hummel, Christian A., Jakob, Gerd, Jochum, Lieselotte, Jocou, Laurent, Kaufer, Andreas, Kellner, Stefan, Kandrew, Sarah, Kern, Lothar, Kervella, Pierre, Kiekebusch, Mario, Klein, Ralf, Köhler, Rainer, Kolb, Johan, Kulas, Martin, Lacour, Sylvestre, Lapeyrère, Vincent, Lazareff, Bernard, Bouquin, Jean-Baptiste Le, Léna, Pierre, Lenzen, Rainer, Lévêque, Samuel, Lin, Chien-Cheng, Lippa, Magdalena, Magnard, Yves, Mehrgan, Leander, Mérand, Antoine, Moulin, Thibaut, Müller, Eric, Müller, Friedrich, Neumann, Udo, Oberti, Sylvain, Ott, Thomas, Pallanca, Laurent, Panduro, Johana, Pasquini, Luca, Paumard, Thibaut, Percheron, Isabelle, Perraut, Karine, Perrin, Guy, Pflüger, Andreas, Duc, Thanh Phan, Plewa, Philipp M., Popovic, Dan, Rabien, Sebastian, Ramírez, Andrés, Ramos, Jose, Rau, Christian, Riquelme, Miguel, Rodríguez-Coira, Gustavo, Rohloff, Ralf-Rainer, Rosales, Alejandra, Rousset, Gérard, Sanchez-Bermudez, Joel, Scheithauer, Silvia, Schöller, Markus, Schuhler, Nicolas, Spyromilio, Jason, Straub, Odele, Straubmeier, Christian, Sturm, Eckhard, Suarez, Marcos, Tristram, Konrad R. W., Ventura, Noel, Vincent, Frédéric, Waisberg, Idel, Wank, Imke, Widmann, Felix, Wieprecht, Ekkehard, Wiest, Michael, Wiezorrek, Erich, Wittkowski, Markus, Woillez, Julien, Wolff, Burkhard, Yazici, Senol, Ziegler, Denis, and Zins, Gérard

Abstract

This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium Cluster with the recently comissioned GRAVITY instrument. We observe a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for $\theta ^1$ Ori B, $\theta ^2$ Ori B, and $\theta ^2$ Ori C. We determine a separation for the previously suspected companion of NU Ori. We confirm four companions for $\theta ^1$ Ori A, $\theta ^1$ Ori C, $\theta ^1$ Ori D, and $\theta ^2$ Ori A, all with substantially improved astrometry and photometric mass estimates. We refine the orbit of the eccentric high-mass binary $\theta ^1$ Ori C and we are able to derive a new orbit for $\theta ^1$ Ori D. We find a system mass of 21.7 $M_{\odot}$ and a period of $53$ days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about 2, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints towards a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We exclude collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion., Comment: Accepted for publication in A&A

Published
2018
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7. A Detection of Sgr A* in the far infrared

Author

von Fellenberg, Sebastiano D., Gillessen, Stefan, Graciá-Carpio, Javier, Fritz, Tobias K., Dexter, Jason, Bauböck, Michi, Ponti, Gabriele, Gao, Feng, Habibi, Maryam, Plewa, Philipp M., Pfuhl, Oliver, Jimenez-Rosales, Alejandra, Waisberg, Idel, Widmann, Felix, Ott, Thomas, Eisenhauer, Frank, Genzel, Reinhard, von Fellenberg, Sebastiano D., Gillessen, Stefan, Graciá-Carpio, Javier, Fritz, Tobias K., Dexter, Jason, Bauböck, Michi, Ponti, Gabriele, Gao, Feng, Habibi, Maryam, Plewa, Philipp M., Pfuhl, Oliver, Jimenez-Rosales, Alejandra, Waisberg, Idel, Widmann, Felix, Ott, Thomas, Eisenhauer, Frank, and Genzel, Reinhard

Abstract

We report the first detection of the Galactic Centre massive black hole, Sgr~A*, in the far infrared. Our measurements were obtained with PACS on board the \emph{Herschel} satellite at $100~\mathrm{\mu m}$ and $160~\mathrm{\mu m}$. While the warm dust in the Galactic Centre is too bright to allow for a direct detection of Sgr~A*, we measure a significant and simultaneous variation of its flux of $\Delta F_{\nu\widehat{=}160 ~\mathrm{\mu m}} = (0.27\pm0.06)~\mathrm{Jy}$ and $\Delta F_{\nu\widehat{=}100 ~\mathrm{\mu m}}= (0.16\pm0.10)~\mathrm{Jy}$ during one observation. The significance level of the $160 ~\mathrm{\mu m}$ band variability is $4.5\sigma$ and the corresponding $100 ~\mathrm{\mu m}$ band variability is significant at $1.6\sigma$. We find no example of an equally significant false positive detection. Conservatively assuming a variability of $25\%$ in the FIR, we can provide upper limits to the flux. Comparing the latter with theoretical models we find that 1D RIAF models have difficulties explaining the observed faintness. However, the upper limits are consistent with modern ALMA and VLA observations. Our upper limits provide further evidence for a spectral peak at $\sim 10^{12} ~ \mathrm{Hz}$ and constrain the number density of $\gamma \sim 100$ electrons in the accretion disk and or outflow., Comment: accepted for publication in APJ

Published
2018
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8. Ionized and molecular gas kinematics in a z=1.4 star-forming galaxy

Author

Übler, Hannah D. N., Genzel, Reinhard, Tacconi, Linda J., Schreiber, Natascha M. Förster, Neri, Roberto, Contursi, Alessandra, Belli, Sirio, Nelson, Erica J., Lang, Philipp, Shimizu, T. Taro, Davies, Ric, Herrera-Camus, Rodrigo, Lutz, Dieter, Plewa, Philipp M., Price, Sedona H., Schuster, Karl, Sternberg, Amiel, Tadaki, Ken-ichi, Wisnioski, Emily, Wuyts, Stijn, Übler, Hannah D. N., Genzel, Reinhard, Tacconi, Linda J., Schreiber, Natascha M. Förster, Neri, Roberto, Contursi, Alessandra, Belli, Sirio, Nelson, Erica J., Lang, Philipp, Shimizu, T. Taro, Davies, Ric, Herrera-Camus, Rodrigo, Lutz, Dieter, Plewa, Philipp M., Price, Sedona H., Schuster, Karl, Sternberg, Amiel, Tadaki, Ken-ichi, Wisnioski, Emily, and Wuyts, Stijn

Abstract

We present deep observations of a $z=1.4$ massive, star-forming galaxy in molecular and ionized gas at comparable spatial resolution (CO 3-2, NOEMA; H$\alpha$, LBT). The kinematic tracers agree well, indicating that both gas phases are subject to the same gravitational potential and physical processes affecting the gas dynamics. We combine the one-dimensional velocity and velocity dispersion profiles in CO and H$\alpha$ to forward-model the galaxy in a Bayesian framework, combining a thick exponential disk, a bulge, and a dark matter halo. We determine the dynamical support due to baryons and dark matter, and find a dark matter fraction within one effective radius of $f_{\rm DM}(\leq$$R_{e})=0.18^{+0.06}_{-0.04}$. Our result strengthens the evidence for strong baryon-dominance on galactic scales of massive $z\sim1-3$ star-forming galaxies recently found based on ionized gas kinematics alone., Comment: accepted for publication in the Astrophysical Journal Letters

Published
2018
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9. Testing General Relativity with the Shadow Size of Sgr A*

Author

Johannsen, Tim, Broderick, Avery E., Plewa, Philipp M., Chatzopoulos, Sotiris, Doeleman, Sheperd S., Eisenhauer, Frank, Fish, Vincent L., Genzel, Reinhard, Gerhard, Ortwin, Johnson, Michael D., Johannsen, Tim, Broderick, Avery E., Plewa, Philipp M., Chatzopoulos, Sotiris, Doeleman, Sheperd S., Eisenhauer, Frank, Fish, Vincent L., Genzel, Reinhard, Gerhard, Ortwin, and Johnson, Michael D.

Abstract

In general relativity, the angular radius of the shadow of a black hole is primarily determined by its mass-to-distance ratio and depends only weakly on its spin and inclination. If general relativity is violated, however, the shadow size may also depend strongly on parametric deviations from the Kerr metric. Based on a reconstructed image of Sagittarius A* (Sgr A*) from a simulated one-day observing run of a seven-station Event Horizon Telescope (EHT) array, we employ a Markov chain Monte Carlo algorithm to demonstrate that such an observation can measure the angular radius of the shadow of Sgr A* with an uncertainty of ~1.5 uas (6%). We show that existing mass and distance measurements can be improved significantly when combined with upcoming EHT measurements of the shadow size and that tight constraints on potential deviations from the Kerr metric can be obtained., Comment: 5+3 pages, 3 Figures

Published
2015
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10. Testing General Relativity with the Shadow Size of Sgr A*

Author

Johannsen, Tim, Broderick, Avery E., Plewa, Philipp M., Chatzopoulos, Sotiris, Doeleman, Sheperd S., Eisenhauer, Frank, Fish, Vincent L., Genzel, Reinhard, Gerhard, Ortwin, Johnson, Michael D., Johannsen, Tim, Broderick, Avery E., Plewa, Philipp M., Chatzopoulos, Sotiris, Doeleman, Sheperd S., Eisenhauer, Frank, Fish, Vincent L., Genzel, Reinhard, Gerhard, Ortwin, and Johnson, Michael D.

Abstract

In general relativity, the angular radius of the shadow of a black hole is primarily determined by its mass-to-distance ratio and depends only weakly on its spin and inclination. If general relativity is violated, however, the shadow size may also depend strongly on parametric deviations from the Kerr metric. Based on a reconstructed image of Sagittarius A* (Sgr A*) from a simulated one-day observing run of a seven-station Event Horizon Telescope (EHT) array, we employ a Markov chain Monte Carlo algorithm to demonstrate that such an observation can measure the angular radius of the shadow of Sgr A* with an uncertainty of ~1.5 uas (6%). We show that existing mass and distance measurements can be improved significantly when combined with upcoming EHT measurements of the shadow size and that tight constraints on potential deviations from the Kerr metric can be obtained., Comment: 5+3 pages, 3 Figures

Published
2015
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11. The Galactic Center cloud G2 and its gas streamer

Author

Pfuhl, Oliver, Gillessen, Stefan, Eisenhauer, Frank, Genzel, Reinhard, Plewa, Philipp M., Ott, Thomas, Ballone, Alessandro, Schartmann, Marc, Burkert, Andreas, Fritz, Tobias K., Sari, Re'em, Steinberg, Elad, Madigan, Ann-Marie, Pfuhl, Oliver, Gillessen, Stefan, Eisenhauer, Frank, Genzel, Reinhard, Plewa, Philipp M., Ott, Thomas, Ballone, Alessandro, Schartmann, Marc, Burkert, Andreas, Fritz, Tobias K., Sari, Re'em, Steinberg, Elad, and Madigan, Ann-Marie

Abstract

We present new, deep near-infrared SINFONI @ VLT integral field spectroscopy of the gas cloud G2 in the Galactic Center, from late summer 2013 and spring 2014. G2 is visible in recombination line emission. The spatially resolved kinematic data track the ongoing tidal disruption. As expected for an observation near pericenter passage, roughly half of the gas in 2014 is found at the redshifted, pre-pericenter side of the orbit, while the other half is at the post-pericenter, blueshifted side. We also present an orbital solution for the gas cloud G1, which was discovered a decade ago in L'-band images when it was spatially almost coincident with Sgr A*. The orientation of the G1 orbit in the three angles is almost identical to the one of G2, but it has a lower eccentricity and smaller semi-major axis. We show that the observed astrometric positions and radial velocities of G1 are compatible with the G2 orbit, assuming that (i) G1 was originally on the G2 orbit preceding G2 by 13 years and (ii) a simple drag force acted on it during pericenter passage. Taken together with the previously described tail of G2, which we detect in recombination line emission and thermal broadband emission, we propose that G2 may be a bright knot in a much more extensive gas streamer. This matches purely gaseous models for G2, such as a stellar wind clump or the tidal debris from a partial disruption of a star., Comment: 28 pages, paper as accepted by ApJ

Published
2014
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12. The Galactic Center cloud G2 and its gas streamer

Author

Pfuhl, Oliver, Gillessen, Stefan, Eisenhauer, Frank, Genzel, Reinhard, Plewa, Philipp M., Ott, Thomas, Ballone, Alessandro, Schartmann, Marc, Burkert, Andreas, Fritz, Tobias K., Sari, Re'em, Steinberg, Elad, Madigan, Ann-Marie, Pfuhl, Oliver, Gillessen, Stefan, Eisenhauer, Frank, Genzel, Reinhard, Plewa, Philipp M., Ott, Thomas, Ballone, Alessandro, Schartmann, Marc, Burkert, Andreas, Fritz, Tobias K., Sari, Re'em, Steinberg, Elad, and Madigan, Ann-Marie

Abstract

We present new, deep near-infrared SINFONI @ VLT integral field spectroscopy of the gas cloud G2 in the Galactic Center, from late summer 2013 and spring 2014. G2 is visible in recombination line emission. The spatially resolved kinematic data track the ongoing tidal disruption. As expected for an observation near pericenter passage, roughly half of the gas in 2014 is found at the redshifted, pre-pericenter side of the orbit, while the other half is at the post-pericenter, blueshifted side. We also present an orbital solution for the gas cloud G1, which was discovered a decade ago in L'-band images when it was spatially almost coincident with Sgr A*. The orientation of the G1 orbit in the three angles is almost identical to the one of G2, but it has a lower eccentricity and smaller semi-major axis. We show that the observed astrometric positions and radial velocities of G1 are compatible with the G2 orbit, assuming that (i) G1 was originally on the G2 orbit preceding G2 by 13 years and (ii) a simple drag force acted on it during pericenter passage. Taken together with the previously described tail of G2, which we detect in recombination line emission and thermal broadband emission, we propose that G2 may be a bright knot in a much more extensive gas streamer. This matches purely gaseous models for G2, such as a stellar wind clump or the tidal debris from a partial disruption of a star., Comment: 28 pages, paper as accepted by ApJ

Published
2014
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