hide
Free keywords:
Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
MPINP:
Hochenergie-Astrophysik Theorie - Abteilung Hofmann
Abstract:
The microquasar SS433 features the most energetic jets known in our Galaxy. A
large fraction of the jet kinetic power is delivered to the surrounding W50
nebula at the jet termination shock, from which high-energy emission and
cosmic-ray production have been anticipated. Here we report on the detection of
a persistent gamma-ray signal from the direction of SS433/W50 with the Fermi
Large Area Telescope. The steady flux and a narrow spectral energy distribution
with a maximum around 250 MeV suggest that gamma-rays are rendered by the bulk
jet kinetic power through proton-proton collisions at the SS433/W50 interaction
regions. If the same mechanism is operating in other baryon-loaded microquasar
jets, their collective contribution may represent a significant fraction of the
total galactic cosmic-ray flux at GeV energies.
