GRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A*
The Event Horizon Telescope will generate horizon scale images of the black hole in the center of the Milky Way, Sgr A∗. Image reconstruction using interferometric visibilities rests on the assumption of a stationary image. We explore the limitations of this assumption using high-cadence disk- and j...
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Astrophysical Journal
2018
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| Online Access: | http://hdl.handle.net/1721.1/118811 https://orcid.org/0000-0001-9147-1841 |
| _version_ | 1826204546006777856 |
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| author | Medeiros, Lia Chan, Chi-kwan Özel, Feryal Psaltis, Dimitrios Kim, Junhan Marrone, Daniel P. Sadowski, Aleksander B |
| author2 | MIT Kavli Institute for Astrophysics and Space Research |
| author_facet | MIT Kavli Institute for Astrophysics and Space Research Medeiros, Lia Chan, Chi-kwan Özel, Feryal Psaltis, Dimitrios Kim, Junhan Marrone, Daniel P. Sadowski, Aleksander B |
| author_sort | Medeiros, Lia |
| collection | MIT |
| description | The Event Horizon Telescope will generate horizon scale images of the black hole in the center of the Milky Way, Sgr A∗. Image reconstruction using interferometric visibilities rests on the assumption of a stationary image. We explore the limitations of this assumption using high-cadence disk- and jet-dominated GRMHD simulations of Sgr A∗. We also employ analytic models that capture the basic characteristics of the images to understand the origin of the variability in the simulated visibility amplitudes. We find that, in all simulations, the visibility amplitudes for baselines oriented parallel and perpendicular to the spin axis of the black hole follow general trends that do not depend strongly on accretion-flow properties. This suggests that fitting Event Horizon Telescope observations with simple geometric models may lead to a reasonably accurate determination of the orientation of the black hole on the plane of the sky. However, in the disk-dominated models, the locations and depths of the minima in the visibility amplitudes are highly variable and are not related simply to the size of the black hole shadow. This suggests that using time-independent models to infer additional black hole parameters, such as the shadow size or the spin magnitude, will be severely affected by the variability of the accretion flow. Key words: accretion, accretion disks, black hole physics, Galaxy: center, radiative transfer |
| first_indexed | 2024-09-23T12:57:11Z |
| format | Article |
| id | mit-1721.1/118811 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T12:57:11Z |
| publishDate | 2018 |
| publisher | Astrophysical Journal |
| record_format | dspace |
| spelling | mit-1721.1/1188112022-09-28T11:07:03Z GRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A* Medeiros, Lia Chan, Chi-kwan Özel, Feryal Psaltis, Dimitrios Kim, Junhan Marrone, Daniel P. Sadowski, Aleksander B MIT Kavli Institute for Astrophysics and Space Research Sadowski, Aleksander B The Event Horizon Telescope will generate horizon scale images of the black hole in the center of the Milky Way, Sgr A∗. Image reconstruction using interferometric visibilities rests on the assumption of a stationary image. We explore the limitations of this assumption using high-cadence disk- and jet-dominated GRMHD simulations of Sgr A∗. We also employ analytic models that capture the basic characteristics of the images to understand the origin of the variability in the simulated visibility amplitudes. We find that, in all simulations, the visibility amplitudes for baselines oriented parallel and perpendicular to the spin axis of the black hole follow general trends that do not depend strongly on accretion-flow properties. This suggests that fitting Event Horizon Telescope observations with simple geometric models may lead to a reasonably accurate determination of the orientation of the black hole on the plane of the sky. However, in the disk-dominated models, the locations and depths of the minima in the visibility amplitudes are highly variable and are not related simply to the size of the black hole shadow. This suggests that using time-independent models to infer additional black hole parameters, such as the shadow size or the spin magnitude, will be severely affected by the variability of the accretion flow. Key words: accretion, accretion disks, black hole physics, Galaxy: center, radiative transfer 2018-10-30T19:28:10Z 2018-10-30T19:28:10Z 2018-04 2017-10 2018-10-11T17:23:22Z Article http://purl.org/eprint/type/JournalArticle 1538-4357 http://hdl.handle.net/1721.1/118811 Medeiros, Lia, et al. “GRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A*.” The Astrophysical Journal, vol. 856, no. 2, Apr. 2018, p. 163. © 2018 The American Astronomical Society. All rights reserved. https://orcid.org/0000-0001-9147-1841 http://dx.doi.org/10.3847/1538-4357/aab204 The 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 Astrophysical Journal IOP Publishing |
| spellingShingle | Medeiros, Lia Chan, Chi-kwan Özel, Feryal Psaltis, Dimitrios Kim, Junhan Marrone, Daniel P. Sadowski, Aleksander B GRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A* |
| title | GRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A* |
| title_full | GRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A* |
| title_fullStr | GRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A* |
| title_full_unstemmed | GRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A* |
| title_short | GRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A* |
| title_sort | grmhd simulations of visibility amplitude variability for event horizon telescope images of sgr a |
| url | http://hdl.handle.net/1721.1/118811 https://orcid.org/0000-0001-9147-1841 |
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