Origin of the hot gas and radio blobs at the Galactic Centre

Abstract

RECENT infrared observations1 have revealed hot gas, with a temperature possibly as high as one million degrees, associated with a small cavity 2 arcseconds in diameter in one of the ionized gas streamers (the 'Bar') that orbit the Galactic Centre radio source SgrA* (ref. 2), thought to contain a massive black hole. Radio continuum observations3 show a chain of blobs of emission leading from SgrA* to the small cavity. We present here further high-resolution radio images which show that the blobs are connected to SgrA*; by a ridge of emission. We suggest that the blobs are formed by the interaction of stellar winds from the IRS16 cluster with the gravitational potential of SgrA*. The hot gas1 then results from the dissipation of the kinetic energy of the blobs as they collide with the orbiting ionized streamer. These collisions are of dynamial significance for the motion of the Bar around the Galactic Centre, and there should be detectable variability in the structure on a timescale of 10 years.