Abstract
The 230 GHz lightcurves of Sagittarius A* (Sgr A*) predicted by general relativistic magnetohydrodynamics and general relativistic ray-tracing (GRRT) models by the Event Horizon Telescope Collaboration have higher variability MΔT compared to observations. In this series of papers, we explore the origin of such large brightness variability. In this first paper, we performed large GRRT parameter surveys that span from the optically thin to the optically thick regimes, covering the ion-to-electron temperature ratio under strongly magnetized conditions, R Low, from 1 to 60. We find that increasing R Low can lead to either an increase or a reduction in MΔT depending on the other model parameters, making it consistent with the observed variability of Sgr A* in some cases. Our analysis of GRRT image snapshots finds that the major contribution to the large MΔT for the Row = 1 models comes from the photon ring. However, secondary contributions from the accretion flow are also visible depending on the spin parameter. Our work demonstrates the importance of the electron temperature used for modeling radiatively inefficient accretion flows and places new constraints on the ion-to-electron temperature ratio. A more in-depth analysis for understanding the dependencies of M ΔT on R Low will be performed in subsequent papers.
Original language | English (US) |
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Article number | 17 |
Journal | Astrophysical Journal |
Volume | 964 |
Issue number | 1 |
DOIs | |
State | Published - Mar 20 2024 |
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science