SPATIALLY RESOLVED NEAR-INFRARED EMISSION AND A BUBBLE OF HOT GAS IN THE CENTRAL ACTIVE REGION OF THE GALAXY

IT has been known for almost two decades that there is a compact, nonthermal radio source within one arcsecond of the dynamical/gravitational centre of our Galaxy 1,2. This source, designated SgrA*, is regarded as the most likely candidate for a central black hole 3. Evidence for an active central source has, however, so far been lacking at infrared wavelengths 4-8. Here we report near-infrared speckle and imaging spectroscopic observations which resolve the central complex (comprising SgrA* and the infrared source IRS16) into about two dozen compact sources. An expanding bubble of hot gas is found to be centred within 3 arcsec of SgrA*. There is also evidence of a blue object, positionally coincident with SgrA*, emitting at 2-mu-m. The hot bubble is probably created by shock excitation of a fast wind. These observations are consistent with the presence of an accreting massive black hole at the Galactic Centre.