Results of the past activity of Sgr A* from X-ray observations of the Galactic center diffuse emission
Abstract
X-ray observations of the diffuse emission at the Galactic center have been performed for more than two decades, revealing an intense and highly-variable non-thermal component spatially correlated with the main molecular complexes. This reflection signal has been identified as echoes created by the past activity of the central supermassive black hole, Sagittarius A*. In particular, the time behaviors and spectra characterized across the whole central molecular zone are successfully explained by several short outbursts during which the black hole was at least a million times brighter than it is today. However, the precise description of the corresponding past catastrophic events is difficult to assess, mainly because the properties of the reflection features that they create while propagating away from Sgr A* depend on the line-of-sight distance, the size, and the morphology of the reflecting clouds, all of which are poorly known. I will review the different attempts to reconstruct Sgr A*'s past activity from the constraints obtained through the observation of the reflection features in the Galactic center, including the 2015-2017 Chandra monitoring and recent NuSTAR observations.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E.669C