CONSTRAINING THE STRUCTURE OF SAGITTARIUS A*'s ACCRETION FLOW WITH MILLIMETER VERY LONG BASELINE INTERFEROMETRY CLOSURE PHASES
Millimeter wave very long baseline interferometry (mm-VLBI) provides access to the emission region surrounding Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, on sub-horizon scales. Recently, a closure phase of 0° ± 40° was reported on a triangle of Earth-sized b...
| Main Authors: | , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
Institute of Physics/American Astronomical Society
2015
|
| Online Access: | http://hdl.handle.net/1721.1/95719 |
| _version_ | 1826214396958867456 |
|---|---|
| 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 wave very long baseline interferometry (mm-VLBI) provides access to the emission region surrounding Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, on sub-horizon scales. Recently, a closure phase of 0° ± 40° was reported on a triangle of Earth-sized baselines (SMT-CARMA-JCMT) representing a new constraint upon the structure and orientation of the emission region, independent from those provided by the previously measured 1.3 mm-VLBI visibility amplitudes alone. Here, we compare this to the closure phases associated with a class of physically motivated, radiatively inefficient accretion flow models and present predictions for future mm-VLBI experiments with the developing Event Horizon Telescope (EHT). We find that the accretion flow models are capable of producing a wide variety of closure phases on the SMT-CARMA-JCMT triangle and thus not all models are consistent with the recent observations. However, those models that reproduce the 1.3 mm-VLBI visibility amplitudes overwhelmingly have SMT-CARMA-JCMT closure phases between ±30°, and are therefore broadly consistent with all current mm-VLBI observations. Improving station sensitivity by factors of a few, achievable by increases in bandwidth and phasing together multiple antennas at individual sites, should result in physically relevant additional constraints upon the model parameters and eliminate the current 180° ambiguity on the source orientation. When additional stations are included, closure phases of order 45°-90° are typical. In all cases, the EHT will be able to measure these with sufficient precision to produce dramatic improvements in the constraints upon the spin of Sgr A*. |
| first_indexed | 2024-09-23T16:04:46Z |
| format | Article |
| id | mit-1721.1/95719 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T16:04:46Z |
| publishDate | 2015 |
| publisher | Institute of Physics/American Astronomical Society |
| record_format | dspace |
| spelling | mit-1721.1/957192022-10-02T06:10:36Z CONSTRAINING THE STRUCTURE OF SAGITTARIUS A*'s ACCRETION FLOW WITH MILLIMETER VERY LONG BASELINE INTERFEROMETRY CLOSURE PHASES Broderick, Avery E. Fish, Vincent L. Doeleman, Sheperd Samuel Loeb, Abraham Haystack Observatory Doeleman, Sheperd Samuel Fish, Vincent L. Millimeter wave very long baseline interferometry (mm-VLBI) provides access to the emission region surrounding Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, on sub-horizon scales. Recently, a closure phase of 0° ± 40° was reported on a triangle of Earth-sized baselines (SMT-CARMA-JCMT) representing a new constraint upon the structure and orientation of the emission region, independent from those provided by the previously measured 1.3 mm-VLBI visibility amplitudes alone. Here, we compare this to the closure phases associated with a class of physically motivated, radiatively inefficient accretion flow models and present predictions for future mm-VLBI experiments with the developing Event Horizon Telescope (EHT). We find that the accretion flow models are capable of producing a wide variety of closure phases on the SMT-CARMA-JCMT triangle and thus not all models are consistent with the recent observations. However, those models that reproduce the 1.3 mm-VLBI visibility amplitudes overwhelmingly have SMT-CARMA-JCMT closure phases between ±30°, and are therefore broadly consistent with all current mm-VLBI observations. Improving station sensitivity by factors of a few, achievable by increases in bandwidth and phasing together multiple antennas at individual sites, should result in physically relevant additional constraints upon the model parameters and eliminate the current 180° ambiguity on the source orientation. When additional stations are included, closure phases of order 45°-90° are typical. In all cases, the EHT will be able to measure these with sufficient precision to produce dramatic improvements in the constraints upon the spin of Sgr A*. Canadian Institute for Theoretical Astrophysics (Beatrice D. Tremaine Fellowship) United States. National Aeronautics and Space Administration (NASA grant NNX08AL43G) United States. National Aeronautics and Space Administration (NASA grant NNA09DB30A) 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) 2015-02-27T15:14:17Z 2015-02-27T15:14:17Z 2011-09 2010-06 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/95719 Broderick, Avery E., Vincent L. Fish, Sheperd S. Doeleman, and Abraham Loeb. “CONSTRAINING THE STRUCTURE OF SAGITTARIUS A*’s ACCRETION FLOW WITH MILLIMETER VERY LONG BASELINE INTERFEROMETRY CLOSURE PHASES.” The Astrophysical Journal 738, no. 1 (August 10, 2011): 38. © 2011 American Astronomical Society. en_US http://dx.doi.org/10.1088/0004-637x/738/1/38 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 CONSTRAINING THE STRUCTURE OF SAGITTARIUS A*'s ACCRETION FLOW WITH MILLIMETER VERY LONG BASELINE INTERFEROMETRY CLOSURE PHASES |
| title | CONSTRAINING THE STRUCTURE OF SAGITTARIUS A*'s ACCRETION FLOW WITH MILLIMETER VERY LONG BASELINE INTERFEROMETRY CLOSURE PHASES |
| title_full | CONSTRAINING THE STRUCTURE OF SAGITTARIUS A*'s ACCRETION FLOW WITH MILLIMETER VERY LONG BASELINE INTERFEROMETRY CLOSURE PHASES |
| title_fullStr | CONSTRAINING THE STRUCTURE OF SAGITTARIUS A*'s ACCRETION FLOW WITH MILLIMETER VERY LONG BASELINE INTERFEROMETRY CLOSURE PHASES |
| title_full_unstemmed | CONSTRAINING THE STRUCTURE OF SAGITTARIUS A*'s ACCRETION FLOW WITH MILLIMETER VERY LONG BASELINE INTERFEROMETRY CLOSURE PHASES |
| title_short | CONSTRAINING THE STRUCTURE OF SAGITTARIUS A*'s ACCRETION FLOW WITH MILLIMETER VERY LONG BASELINE INTERFEROMETRY CLOSURE PHASES |
| title_sort | constraining the structure of sagittarius a s accretion flow with millimeter very long baseline interferometry closure phases |
| url | http://hdl.handle.net/1721.1/95719 |
| work_keys_str_mv | AT broderickaverye constrainingthestructureofsagittariusasaccretionflowwithmillimeterverylongbaselineinterferometryclosurephases AT fishvincentl constrainingthestructureofsagittariusasaccretionflowwithmillimeterverylongbaselineinterferometryclosurephases AT doelemansheperdsamuel constrainingthestructureofsagittariusasaccretionflowwithmillimeterverylongbaselineinterferometryclosurephases AT loebabraham constrainingthestructureofsagittariusasaccretionflowwithmillimeterverylongbaselineinterferometryclosurephases |