Introduction

The center of our Galaxy harbours a massive black hole, and the surrounding region including the central super massive black holes (SMBH) is customary referred as Sgr A* as a whole. Sgr A* shows frequent flares originating from the direct vicinity of the central black hole. In the X-ray band, multiple flares are superimposed on a steady, extended emission. The duration of the flares ranges from half an hour to several hours, while the rise/decay time is found to be of the order of few hundred seconds. Variable emission has also been detected in the NIR band.

The properties of the flare emission suggest that such flares originate in the innermost part of accretion flow onto the central black hole, and one needs to introduce an appropriate theoretical model of accretion to understand these flares, keeping in the mind that the material accreting onto Sgr A* most probably comes from the nearby stars.