Speaker
Description
The Galaxy's supermassive black hole is a hundred times closer than any other massive singularity. It is surrounded by a highly unstable gas disk so why is the black hole so peaceful at the present time? This mystery has led to a flurry of models in order to explain why Sgr A is radiating far below (1 part in 10^8) the Eddington accretion limit. But has this always been so? Evidence is gathering that Sgr A has been far more active in the recent past, on timescales of thousands of years and longer. The bipolar wind discovered by MSX, the X-ray/gamma-ray bubbles discovered by ROSAT/Fermi-LAT, the WMAP haze, the positronium flash confirmed by INTEGRAL, and new UV spectroscopy
from HST are suggestive of something truly spectacular in the recent past. We present new evidence that the Galactic Centre was a full blown "active galaxy" just a few million years ago. The echo of this incredible event can be seen today imprinted across the Galaxy. This leads us to a developing paradigm for Sgr A* activity over billions of years.
