@article{13420,
  author = {A. Grigorian and Jason Dexter},
  title = {The relationship between simulated sub-millimeter and near-infrared images of Sagittarius A* from a magnetically arrested black hole accretion flow},
  abstract = {<p><jats:p>Sagittarius A* (Sgr A*), the supermassive black hole at the centre of the Milky Way, undergoes large-amplitude near-infrared (NIR) flares that can coincide with the continuous rotation of the NIR emission region. One promising explanation for this observed NIR behaviour is a magnetic flux eruption, which occurs in three-dimensional General Relativistic Magneto-Hydrodynamic (3D GRMHD) simulations of magnetically arrested accretion flows. After running two-temperature 3D GRMHD simulations, where the electron temperature is evolved self-consistently along with the gas temperature, it is possible to calculate ray-traced images of the synchotron emission from thermal electrons in the accretion flow. Changes in the gas-dominated (σ&nbsp;= b2/2ρ &amp;lt; 1) regions of the accretion flow during a magnetic flux eruption reproduce the NIR flaring and NIR emission region rotation of Sgr A* with durations consistent with observation. In this paper, we demonstrate that these models also predict that large (1.5x – 2x) size increases of the sub-millimeter (sub-mm) and millimeter (mm) emission region follow most NIR flares by 20–50 min. These size increases occur across a wide parameter space of black hole spin (a&nbsp;= 0.3, 0.5, −0.5, and 0.9375) and initial tilt angle between the accretion flow and black hole spin axes θ0 (θ0&nbsp;= 0°, 16°, and 30°). We also calculate the sub-mm polarization angle rotation and the shift of the sub-mm spectral index from zero to –0.8 during a prominent NIR flare in our high spin (a&nbsp;= 0.9375) simulation. We show that, during a magnetic flux eruption, a large (∼10rg), magnetically dominated (σ &amp;gt; 1), low-density, and high-temperature ‘bubble’ forms in the accretion flow. The drop in density inside the bubble and additional electron heating in accretion flow between 15rg and 25rg leads to a sub-mm size increase in corresponding images.</jats:p></p>
},
  year = {2024},
  journal = {Monthly Notices of the Royal Astronomical Society},
  volume = {530},
  pages = {1563-1579},
  month = {2024-04},
  publisher = {Oxford University Press (OUP)},
  issn = {0035-8711, 1365-2966},
  doi = {10.1093/mnras/stae934},
}