Modulated X-ray Emissivity near the Stress Edge in Sgr A*

TL;DR

This paper uses ray-tracing simulations to model X-ray luminosity modulation near the stress edge of Sgr A*, explaining observed flare variability through general relativistic effects in a hot, magnetized accretion flow.

Contribution

It introduces a novel simulation approach to connect plasma dynamics near the stress edge with observed X-ray flare modulation in Sgr A*.

Findings

Simulated lightcurves show quasi-periodic modulation matching observed flares.

Magnetic coupling influences X-ray emission near the stress edge.

Relativistic effects are key to understanding flare variability.

Abstract

Sgr A* is thought to be the radiative manifestation of a ~3.6E6 Msun supermassive black hole at the Galactic center. Its mm/sub-mm spectrum and its flare emission at IR and X-ray wavelengths may be produced within the inner ten Schwarzschild radii of a hot, magnetized Keplerian flow. The lightcurve produced in this region may exhibit quasi-periodic variability. We present ray-tracing simulations to determine the general-relativistically modulated X-ray luminosity expected from plasma coupled magnetically to the rest of the disk as it spirals inwards below the innermost stable circular orbit towards the "stress edge" in the case of a Schwarzschild metric. The resulting lightcurve exhibits a modulation similar to that observed during a recent X-ray flare from Sgr A*.