Akiyama, Kazunori;
Alberdi, Antxon;
Alef, Walter;
Algaba, Juan Carlos;
Anantua, Richard;
Asada, Keiichi;
Azulay, Rebecca;
... White, Chris; + view all
(2022)
First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole.
The Astrophysical Journal Letters
, 930
(2)
, Article L16. 10.3847/2041-8213/ac6672.
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Abstract
In this paper we provide a first physical interpretation for the Event Horizon Telescope's (EHT) 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohydrodynamics simulations, including aligned, tilted, and stellar-wind-fed simulations; radiative transfer is performed assuming both thermal and nonthermal electron distribution functions. We test the models against 11 constraints drawn from EHT 230 GHz data and observations at 86 GHz, 2.2 μm, and in the X-ray. All models fail at least one constraint. Light-curve variability provides a particularly severe constraint, failing nearly all strongly magnetized (magnetically arrested disk (MAD)) models and a large fraction of weakly magnetized models. A number of models fail only the variability constraints. We identify a promising cluster of these models, which are MAD and have inclination i ≤ 30°. They have accretion rate (5.2–9.5) × 10−9 M ⊙ yr−1, bolometric luminosity (6.8–9.2) × 1035 erg s−1, and outflow power (1.3–4.8) × 1038 erg s−1. We also find that all models with i ≥ 70° fail at least two constraints, as do all models with equal ion and electron temperature; exploratory, nonthermal model sets tend to have higher 2.2 μm flux density; and the population of cold electrons is limited by X-ray constraints due to the risk of bremsstrahlung overproduction. Finally, we discuss physical and numerical limitations of the models, highlighting the possible importance of kinetic effects and duration of the simulations.
| Type: | Article |
|---|---|
| Title: | First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/2041-8213/ac6672 |
| Publisher version: | https://doi.org/10.3847/2041-8213/ac6672 |
| Language: | English |
| Additional information: | Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. |
| Keywords: | ADVECTION-DOMINATED ACCRETION, MAGNETICALLY ARRESTED ACCRETION, OPTICALLY THICK ACCRETION, ADAPTIVE MESH REFINEMENT, 3D GRMHD SIMULATIONS, IN-CELL SIMULATIONS, PAIR PRODUCING GAPS, MAGNETOHYDRODYNAMIC SIMULATIONS, NUMERICAL SIMULATIONS, PARTICLE-ACCELERATION |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10149326 |
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