EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A*
Millimeter very long baseline interferometry (mm-VLBI) provides the novel capacity to probe the emission region of a handful of supermassive black holes on sub-horizon scales. For Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, this provides access to the region...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | en_US |
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Institute of Physics/American Astronomical Society
2015
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| Online Access: | http://hdl.handle.net/1721.1/96209 |
| _version_ | 1811092507650424832 |
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| author | Broderick, Avery E. Fish, Vincent L. Doeleman, Sheperd Samuel Loeb, Abraham |
| author2 | Haystack Observatory |
| author_facet | Haystack Observatory Broderick, Avery E. Fish, Vincent L. Doeleman, Sheperd Samuel Loeb, Abraham |
| author_sort | Broderick, Avery E. |
| collection | MIT |
| description | Millimeter very long baseline interferometry (mm-VLBI) provides the novel capacity to probe the emission region of a handful of supermassive black holes on sub-horizon scales. For Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, this provides access to the region in the immediate vicinity of the horizon. Broderick et al. have already shown that by leveraging spectral and polarization information as well as accretion theory, it is possible to extract accretion-model parameters (including black hole spin) from mm-VLBI experiments containing only a handful of telescopes. Here we repeat this analysis with the most recent mm-VLBI data, considering a class of aligned, radiatively inefficient accretion flow (RIAF) models. We find that the combined data set rules out symmetric models for Sgr A*'s flux distribution at the 3.9σ level, strongly favoring length-to-width ratios of roughly 2.4:1. More importantly, we find that physically motivated accretion flow models provide a significantly better fit to the mm-VLBI observations than phenomenological models, at the 2.9σ level. This implies that not only is mm-VLBI presently capable of distinguishing between potential physical models for Sgr A*'s emission, but further that it is sensitive to the strong gravitational lensing associated with the propagation of photons near the black hole. Based upon this analysis we find that the most probable magnitude, viewing angle, and position angle for the black hole spin are a = 0.0+0.64 + 0.86, $\theta ={68^\circ }^{+5^\circ +9^\circ }_{-20^\circ -28^\circ }$, and $\xi ={-52^\circ }^{+17^\circ +33^\circ }_{-15^\circ -24^\circ }$ east of north, where the errors quoted are the 1σ and 2σ uncertainties. |
| first_indexed | 2024-09-23T15:19:18Z |
| format | Article |
| id | mit-1721.1/96209 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:19:18Z |
| publishDate | 2015 |
| publisher | Institute of Physics/American Astronomical Society |
| record_format | dspace |
| spelling | mit-1721.1/962092022-10-02T02:08:05Z EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* Broderick, Avery E. Fish, Vincent L. Doeleman, Sheperd Samuel Loeb, Abraham Haystack Observatory Fish, Vincent L. Doeleman, Sheperd Samuel Millimeter very long baseline interferometry (mm-VLBI) provides the novel capacity to probe the emission region of a handful of supermassive black holes on sub-horizon scales. For Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, this provides access to the region in the immediate vicinity of the horizon. Broderick et al. have already shown that by leveraging spectral and polarization information as well as accretion theory, it is possible to extract accretion-model parameters (including black hole spin) from mm-VLBI experiments containing only a handful of telescopes. Here we repeat this analysis with the most recent mm-VLBI data, considering a class of aligned, radiatively inefficient accretion flow (RIAF) models. We find that the combined data set rules out symmetric models for Sgr A*'s flux distribution at the 3.9σ level, strongly favoring length-to-width ratios of roughly 2.4:1. More importantly, we find that physically motivated accretion flow models provide a significantly better fit to the mm-VLBI observations than phenomenological models, at the 2.9σ level. This implies that not only is mm-VLBI presently capable of distinguishing between potential physical models for Sgr A*'s emission, but further that it is sensitive to the strong gravitational lensing associated with the propagation of photons near the black hole. Based upon this analysis we find that the most probable magnitude, viewing angle, and position angle for the black hole spin are a = 0.0+0.64 + 0.86, $\theta ={68^\circ }^{+5^\circ +9^\circ }_{-20^\circ -28^\circ }$, and $\xi ={-52^\circ }^{+17^\circ +33^\circ }_{-15^\circ -24^\circ }$ east of north, where the errors quoted are the 1σ and 2σ uncertainties. National Science Foundation (U.S.) (NSF grant AST-0907890) National Science Foundation (U.S.) (NSF grant AST-0807843) National Science Foundation (U.S.) (NSF grant AST-0905844) United States. National Aeronautics and Space Administration (NASA grant NNX08AL43G) United States. National Aeronautics and Space Administration (NASA grant NNA09DB30A) Canadian Institute for Theoretical Astrophysics (Beatrice D. Tremaine Fellowship) 2015-03-27T15:19:45Z 2015-03-27T15:19:45Z 2011-07 2010-11 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/96209 Broderick, Avery E., Vincent L. Fish, Sheperd S. Doeleman, and Abraham Loeb. “EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A*.” The Astrophysical Journal 735, no. 2 (June 23, 2011): 110. © 2011 American Astronomical Society. en_US http://dx.doi.org/10.1088/0004-637x/735/2/110 Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf Institute of Physics/American Astronomical Society American Astronomical Society |
| spellingShingle | Broderick, Avery E. Fish, Vincent L. Doeleman, Sheperd Samuel Loeb, Abraham EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* |
| title | EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* |
| title_full | EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* |
| title_fullStr | EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* |
| title_full_unstemmed | EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* |
| title_short | EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* |
| title_sort | evidence for low black hole spin and physically motivated accretion models from millimeter vlbi observations of sagittarius a |
| url | http://hdl.handle.net/1721.1/96209 |
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