The Relationship Between Simulated Sub-Millimeter and Near-Infrared Images of Sagittarius A* from a Magnetically Arrested Black Hole Accretion Flow

Abstract

Sagittarius A* (Sgr A*), the supermassive black hole at the center 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 behavior 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 ($\sigma =b^2/2\rho <1$) 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 minutes. These size increases occur across a wide parameter space of black hole spin ($a=0.3,0.5,-0.5,0.9375$) and initial tilt angle between the accretion flow and black hole spin axes ${\theta }_0$ (${\theta }_0=0^{\circ }$, $16^{\circ }$, $30^{\circ }$). 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 ($a=0.9375$) simulation. We show that, during a magnetic flux eruption, a large ($\sim 10r_g$), magnetically dominated $(\sigma >1)$, 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 15$r_g$ - 25$r_g$ leads to a sub-mm size increase in corresponding images.

18 pages, 15 figures. Monthly Notices of the Royal Astronomical Society, 2024

References in corpus (20)

• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
• Black hole flares: ejection of accreted magnetic flux through 3D plasmoid-mediated reconnection
• A polarised infrared flare from Sagittarius A* and the signatures of orbiting plasma hotspots
• Ab Initio Horizon-Scale Simulations of Magnetically Arrested Accretion in Sagittarius A* Fed by Stellar Winds
• Sgr A* near-infrared flares from reconnection events in a magnetically arrested disc
• Millimeter light curves of Sagittarius A* observed during the 2017 Event Horizon Telescope campaign
• Orbital motion near Sagittarius A* -- Constraints from polarimetric ALMA observations
• Polarized NIR and X-ray Flares from SgrA*
• Magnetic Hair and Reconnection in Black Hole Magnetospheres
• The Submillimeter Polarization of Sgr A*
• Constraining particle acceleration in Sgr A* with simultaneous GRAVITY, Spitzer, NuSTAR and Chandra observations
• Radiative reconnection-powered TeV flares from the black hole magnetosphere in M87
• The Flux Distribution of Sgr A*
• Particle Injection and Nonthermal Particle Acceleration in Relativistic Magnetic Reconnection
• Spectral and Imaging properties of Sgr A* from High-Resolution 3D GRMHD Simulations with Radiative Cooling
• Particle acceleration by magnetic Rayleigh-Taylor instability: mechanism for flares in black-hole accretion flows
• Persistent Non-Gaussian Structure in the Image of Sagittarius A* at 86 GHz

Cited by in corpus (3)

• New Evidence for a Flux-independent Spectral Index of Sgr A* in the Near-infrared
• Non-thermal Synchrotron Emission and Polarization Signatures during Black Hole Flux Eruptions
• Radiative Cooling Effects on Plasmoid Formation in Black Hole Accretion Flows with Multiple Magnetic Loops