While the supermassive black hole Sgr A* at the center of the Milky Way it experienced a powerful outburst of X-ray radiation hundreds of years ago. The historical records of this outburst are revealed by reflection/reprocessed radiation coming from dense molecular clouds. The is currently very dim, we believe that imprints left by the outburst in spatial and time variations of the reflected emission suggest that the outburst happened some hundred years ago. It lasted less than several years and Sgr A* was about hundred million times brighter than today. These characteristics are consistent with a relatively modest tidal disruption event. Thus, molecular clouds offer us a convenient tool to study SgrA*’s past history. At the same time, the outburst serves as an extremely powerful probe of molecular gas. Essentially, this is the only opportunity to reconstruct a full 3D structure of molecular clouds and their mass distribution. Future X-ray observatories, including cryogenic bolometers and polarimeters, will further boost our ability to conduct in-depth studies of molecular gas and outbursts of Sgr A*.
Host: Claude Canizares
Refreshments at 3:45pm; talk begins at 4:00pm