The spectrum of Sgr A* and its variability

TL;DR

This paper shows that a single physical process, optically thin synchrotron radiation from relativistic electrons, explains both the spectrum and variability of Sgr A* across a wide frequency range, with variability driven by accretion disk energy input.

Contribution

It demonstrates that a unified synchrotron emission model accounts for Sgr A*'s spectrum and variability, simplifying previous multi-process explanations.

Findings

Synchrotron radiation explains the spectrum from 1 to 1000 GHz.

Variability is linked to energy input from the accretion disk.

A single physical process suffices for both spectrum and variability.

Abstract

We demonstrate that there is only one physical process required to explain the spectrum and the variability of the radio source at the dynamical center of our Galaxy, Sgr A*, in the frequency range from $\approx$1 to $\approx$1000 GHz, namely optically thin synchrotron radiation that is emitted from a population of relativistic electrons. We attribute the observed variability to variable energy input from an accretion disk around Sgr A* into the acceleration of the electrons.