Evidence for Gamma-ray Jets in the Milky Way

TL;DR

This paper presents evidence for gamma-ray jets in the Milky Way, identified through features in the gamma-ray bubbles that suggest past jet activity from the central black hole, marking the first resolved gamma-ray jets observed in our galaxy.

Contribution

The study reports the discovery of jet-like gamma-ray features in the Milky Way, providing the first resolved gamma-ray jets in our galaxy and evidence of past black hole activity.

Findings

Identification of a gamma-ray cocoon and jet-like features in the Milky Way.

Spectral analysis shows a hard spectrum with index ~ -2 from 1 to 100 GeV.

Estimated luminosities of the cocoon and jet-like features.

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 a sign 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 luminosity of (5.5 +/- 0.45) x 10^35 erg/s and luminosity of the jet-like feature of (1.8 +/- 0.35) x 10^35 erg/s at 1 to 100 GeV. If confirmed, these jets are the first resolved gamma-ray jets ever seen.