Plasma evolution around Sgr A*
Abstract
We present a new way of describing the flares occurring in the Galactic Center. We model Sgr A* within a single zone with a self-consistent calculation of the particle distribution. All the relevant radiative processes are taken into account in the evolution of the electron distribution and in the resulting spectrum. We explore the multi-wavelength quiescent and flaring spectra from Sgr A*. We present some spectral modelling for the new X-ray data flares observed by NuSTAR in July 2012, together with older observations in different wavelengths, and we discuss the physical parameters that need to be modified in the plasma in order to produce a flare. The results allow us to give an interpretation to the flaring events generated very close to the central super-massive black hole without assuming a given particle distribution. We conclude that the flare data (including the new X-ray flare) are more likely generated by a weakly magnetized plasma in which particles can be injected and escape. Such a plasma, with prescription for non-thermal acceleration, injection, escape and cooling losses, gives a spectrum with a break between the infra-red and the X-ray, allowing a better simultaneous match in the different wavelengths. Even-though inverse Compton emission for the X-ray flare is not excluded, the parameters favour the non-thermal synchrotron spectrum. We also consider a modification of Sgr A* quiescent spectrum with an increase of the plasma density in order to give an observable prediction of what is likely to be happening when the cloud G2 falls into the Galactic Centre this year.
- Publication:
-
American Astronomical Society Meeting Abstracts #223
- Pub Date:
- January 2014
- Bibcode:
- 2014AAS...22323802D