Variability in GRMHD Simulations of Sgr A* : Implications for EHT Closure Phase Observations
Closure phases along different baseline triangles carry a large amount of information regarding the structures of the images of black holes in interferometric observations with the Event Horizon Telescope. We use long time span, high cadence, GRMHD+radiative transfer models of Sgr A* to investigate...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | en_US |
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IOP Publishing
2018
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| Online Access: | http://hdl.handle.net/1721.1/113563 https://orcid.org/0000-0001-9147-1841 |
| _version_ | 1811089841347100672 |
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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 | Closure phases along different baseline triangles carry a large amount of information regarding the structures of the images of black holes in interferometric observations with the Event Horizon Telescope. We use long time span, high cadence, GRMHD+radiative transfer models of Sgr A* to investigate the expected variability of closure phases in such observations. We find that, in general, closure phases along small baseline triangles show little variability, except in the cases when one of the triangle vertices crosses one of the small regions of low visibility amplitude. The closure phase variability increases with the size of the baseline triangle, as larger baselines probe the small-scale structures of the images, which are highly variable. On average, the funnel-dominated MAD models show less closure phase variability than the disk-dominated SANE models, even in the large baseline triangles, because the images from the latter are more sensitive to the turbulence in the accretion flow. Our results suggest that image reconstruction techniques need to explicitly take into account the closure phase variability, especially if the quality and quantity of data allow for a detailed characterization of the nature of variability. This also implies that, if image reconstruction techniques that rely on the assumption of a static image are utilized, regions of the u–v space that show a high level of variability will need to be identified and excised. |
| first_indexed | 2024-09-23T14:25:30Z |
| format | Article |
| id | mit-1721.1/113563 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T14:25:30Z |
| publishDate | 2018 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/1135632022-09-29T09:24:33Z Variability in GRMHD Simulations of Sgr A* : Implications for EHT Closure Phase Observations 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 Closure phases along different baseline triangles carry a large amount of information regarding the structures of the images of black holes in interferometric observations with the Event Horizon Telescope. We use long time span, high cadence, GRMHD+radiative transfer models of Sgr A* to investigate the expected variability of closure phases in such observations. We find that, in general, closure phases along small baseline triangles show little variability, except in the cases when one of the triangle vertices crosses one of the small regions of low visibility amplitude. The closure phase variability increases with the size of the baseline triangle, as larger baselines probe the small-scale structures of the images, which are highly variable. On average, the funnel-dominated MAD models show less closure phase variability than the disk-dominated SANE models, even in the large baseline triangles, because the images from the latter are more sensitive to the turbulence in the accretion flow. Our results suggest that image reconstruction techniques need to explicitly take into account the closure phase variability, especially if the quality and quantity of data allow for a detailed characterization of the nature of variability. This also implies that, if image reconstruction techniques that rely on the assumption of a static image are utilized, regions of the u–v space that show a high level of variability will need to be identified and excised. 2018-02-12T15:02:23Z 2018-02-12T15:02:23Z 2017-07 2017-05 Article http://purl.org/eprint/type/JournalArticle 1538-4357 0004-637X http://hdl.handle.net/1721.1/113563 Medeiros, Lia, et al. “Variability in GRMHD Simulations of Sgr A*: Implications for EHT Closure Phase Observations.” The Astrophysical Journal, vol. 844, no. 1, July 2017, p. 35. © 2017 The American Astronomical Society https://orcid.org/0000-0001-9147-1841 en_US http://dx.doi.org/10.3847/1538-4357/aa7751 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 IOP Publishing IOP Publishing |
| spellingShingle | Medeiros, Lia Chan, Chi-kwan Özel, Feryal Psaltis, Dimitrios Kim, Junhan Marrone, Daniel P. Sadowski, Aleksander B Variability in GRMHD Simulations of Sgr A* : Implications for EHT Closure Phase Observations |
| title | Variability in GRMHD Simulations of Sgr A* : Implications for EHT Closure Phase Observations |
| title_full | Variability in GRMHD Simulations of Sgr A* : Implications for EHT Closure Phase Observations |
| title_fullStr | Variability in GRMHD Simulations of Sgr A* : Implications for EHT Closure Phase Observations |
| title_full_unstemmed | Variability in GRMHD Simulations of Sgr A* : Implications for EHT Closure Phase Observations |
| title_short | Variability in GRMHD Simulations of Sgr A* : Implications for EHT Closure Phase Observations |
| title_sort | variability in grmhd simulations of sgr a implications for eht closure phase observations |
| url | http://hdl.handle.net/1721.1/113563 https://orcid.org/0000-0001-9147-1841 |
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