Polarized light from Sagittarius A* in the near-infrared K_{s}-band
Banafsheh Shahzamanian,Banafsheh Shahzamanian,Andreas Eckart,Andreas Eckart,M. Valencia-S.,G. Witzel,Mohammad Zamaninasab,Nadeen B. Sabha,Nadeen B. Sabha,Macarena Garcia-Marin,Vladimir Karas,G. D. Karssen,A. Borkar,A. Borkar,Michal Dovciak,D. Kunneriath,Michal Bursa,R. M. Buchholz,J. Moultaka,Christian Straubmeier +19 more
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In this article, the authors present a statistical analysis of polarized near-infrared light from Sgr A*, the radio source associated with the supermassive black hole at the center of the Milky Way.Abstract:
We present a statistical analysis of polarized near-infrared light from Sgr A*, the radio source associated with the supermassive black hole at the center of the Milky Way. The observations were carried out using the adaptive optics instrument NACO at the VLT UT4 in the infrared K s -band from 2004 to 2012. Several polarized flux excursions were observed during these years. Linear polarization at 2.2 μ m, its statistics, and time variation, can be used constrain the physical conditions of the accretion process onto this supermassive black hole. With an exponent of about 4 for the number density histogram of fluxes above 5 mJy, the distribution of polarized flux density is closely linked to the single state power-law distribution of the total K s -band flux densities reported earlier. We find typical polarization degrees on the order of 20% ± 10% and a preferred polarization angle of 13° ± 15°. Simulations show the uncertainties under a total flux density of ~2 mJy are probably dominated by observational effects. At higher flux densities there are intrinsic variations of polarization degree and angle within well constrained ranges. Since the emission is most likely due to optically thin synchrotron radiation, the preferred polarization angle we find is very likely coupled to the intrinsic orientation of the Sgr A* system, i.e. a disk or jet/wind scenario associated with the supermassive black hole. If they are indeed linked to structural features of the source the data imply a rather stable geometry and accretion process for the Sgr A* system.read more
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Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA
Roberto Abuter,António Amorim,M. Bauböck,Jean-Philippe Berger,H. Bonnet,Wolfgang Brandner,Yann Clénet,V. Coudé du Foresto,P. T. de Zeeuw,P. T. de Zeeuw,Casey Deen,Jason Dexter,Gilles Duvert,Andreas Eckart,Andreas Eckart,Frank Eisenhauer,N. M. Förster Schreiber,Paulo J. V. Garcia,Paulo J. V. Garcia,Paulo J. V. Garcia,Feng Gao,Eric Gendron,Reinhard Genzel,Reinhard Genzel,Stefan Gillessen,P. Guajardo,Maryam Habibi,Xavier Haubois,Th. Henning,Stefan Hippler,Matthew Horrobin,Armin Huber,A. Jiménez-Rosales,Laurent Jocou,Pierre Kervella,Sylvestre Lacour,Sylvestre Lacour,V. Lapeyrère,Bernard Lazareff,J.-B. Le Bouquin,Pierre Léna,Magdalena Lippa,Thomas Ott,Johana Panduro,Thibaut Paumard,Karine Perraut,Guy Perrin,Oliver Pfuhl,P. M. Plewa,Sebastian Rabien,G. Rodríguez-Coira,Gérard Rousset,Amiel Sternberg,Amiel Sternberg,Odele Straub,Christian Straubmeier,Eckhard Sturm,Linda J. Tacconi,Frederic H. Vincent,S. von Fellenberg,Idel Waisberg,Felix Widmann,Ekkehard Wieprecht,Erich Wiezorrek,Julien Woillez,S. Yazici,S. Yazici +66 more
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IPOLE - semi-analytic scheme for relativistic polarized radiative transport
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Journal ArticleDOI
The Milky Way’s Supermassive Black Hole: How Good a Case Is It?
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TL;DR: In this paper, a review of the observational facts, theoretical grounds and conceptual aspects for the case of Sagittarius A* being a black hole is discussed using causation as an indispensable element.
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Variability Timescale and Spectral Index of Sgr A* in the Near Infrared: Approximate Bayesian Computation Analysis of the Variability of the Closest Supermassive Black Hole.
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TL;DR: In this paper, the authors present an analysis of the most comprehensive NIR variability data set of Sagittarius A* to date: eight 24 hr epochs of continuous monitoring of Sgr A* at 4.5 μm with the IRAC instrument on the Spitzer Space Telescope, 93 epochs from 2.18 μm data from Naos Conica at the Very Large Telescope, and 30 epoch of 2.12 μm from the NIRC2 camera at the Keck Observatory, in total 94,929 measurements.
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