Evidence for gamma-ray jets in the Milky Way

Abstract

Although accretion onto supermassive black holes in other galaxies is seen to produce powerful jets in X-ray and radio, no convincing detection has ever been made of a kpc-scale jet in the Milky Way. The recently discovered pair of 10 kpc tall gamma-ray bubbles in our Galaxy may be signs of earlier jet activity from the central black hole. In this paper, we identify a gamma-ray cocoon feature in the southern bubble, a jet-like feature along the cocoon's axis of symmetry, and another directly opposite the Galactic center in the north. Both the cocoon and jet-like feature have a hard spectrum with spectral index ~ – 2 from 1 to 100 GeV, with a cocoon total luminosity of (5.5 ± 0.45) × 1035 and luminosity of the jet-like feature of (1.8 ± 0.35) × 1035 erg s–1 at 1-100 GeV. If confirmed, these jets are the first resolved gamma-ray jets ever seen.