Multistructured Accretion Flow of Sgr A*. I. Examination of a Radiatively Inefficient Accretion Flow Mode
| Author(s) | Balakrishnan, Mayura | |
| Author(s) | Corrales, Lia | |
| Author(s) | Markoff, Sera | |
| Author(s) | Nowak, Michael | |
| Author(s) | Haggard, Daryl | |
| Author(s) | Wang, Q. Daniel | |
| Author(s) | Neilsen, Joey | |
| Author(s) | Russell, Christopher M. P. | |
| Author(s) | Calderón, Diego | |
| Author(s) | Cuadra, Jorge | |
| Date Accessioned | 2024-10-17T16:48:46Z | |
| Date Available | 2024-10-17T16:48:46Z | |
| Publication Date | 2024-10-08 | |
| Description | This article was originally published in The Astrophysical Journal. The version of record is available at: https://doi.org/10.3847/1538-4357/ad6c08. © 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence (http://creativecommons.org/licenses/by/4.0/). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. | |
| Abstract | The extreme low-luminosity supermassive black hole Sgr A* provides a unique laboratory in which to test models of radiatively inefficient accretion flows (RIAFs). Previous fits to the quiescent Chandra ACIS-S spectrum found that a RIAF model with an equal inflow–outflow balance works well. In this work, we apply the RIAF model to the Chandra HETG-S spectrum obtained through the Chandra X-ray Visionary Program, which displays features suggestive of temperature and velocity structures within the plasma. A comprehensive forward model analysis accounting for the accretion flow geometry and HETG-S instrumental effects is required for a full interpretation of the quiescent Chandra HETG-S spectrum. We present a RIAF model that takes these effects into account. Our fits to the high-resolution grating spectrum indicate an inflow balanced by an outflow (s ∼ 1) alongside a temperature profile that appears shallower than what would be expected from a gravitational potential following 1/r. The data require that the abundance of iron relative to solar is ZFe < 0.32 Z⊙ (90% credible interval), much lower than the 2 Z⊙ metallicity measured in nearby late-type giants. While future missions like NewAthena will provide higher spectral resolution, source separation will continue to be a problem. Leveraging Chandra's unparalleled spatial resolution, which is not expected to be surpassed for decades, remains essential for detailed investigations of the densely populated Galactic center in X-rays. | |
| Sponsor | We would like to thank the anonymous referee for their helpful and insightful responses. The original Chandra data set used in this work was made possible by the Chandra X-ray Visionary Program through Chandra Award Number GO2-13110A, issued by the Chandra X-ray Center (CXC), which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060. The Chandra data sets are contained in DOI:10.25574/cdc.275. Authors M.B., L.C., and C.R. were supported by the CXC grants program, award AR2-23015A and AR2-23015B. D.C. is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy—EXC 2121—Quantum Universe'— 390833306. J.C. acknowledges financial support from ANID (FONDECYT 1211429 and Millennium Nucleus TITANS, NCN2023_002). D.H. acknowledges funding from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Research Chairs (CRC) program. | |
| Citation | Balakrishnan, Mayura, Lia Corrales, Sera Markoff, Michael Nowak, Daryl Haggard, Q. Daniel Wang, Joey Neilsen, et al. “Multistructured Accretion Flow of Sgr A*. I. Examination of a Radiatively Inefficient Accretion Flow Model.” The Astrophysical Journal 974, no. 1 (October 1, 2024): 98. https://doi.org/10.3847/1538-4357/ad6c08. | |
| ISSN | 1538-4357 | |
| URL | https://udspace.udel.edu/handle/19716/35269 | |
| Language | en_US | |
| Publisher | The Astrophysical Journal | |
| dc.rights | Attribution 4.0 International | en |
| dc.rights.uri | http://creativecommons.org/licenses/by/4.0/ | |
| Title | Multistructured Accretion Flow of Sgr A*. I. Examination of a Radiatively Inefficient Accretion Flow Mode | |
| Type | Article |
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