Fermi gamma-ray "bubbles" from stochastic acceleration of electrons.

Journal article

Gamma-ray data from Fermi Large Area Telescope reveal a bilobular structure extending up to ∼50° above and below the Galactic Center. It has been argued that the gamma rays arise from hadronic interactions of high-energy cosmic rays which are advected out by a strong wind, or from inverse-Compton scattering of relativistic electrons accelerated at plasma shocks present in the bubbles. We explore the alternative possibility that the relativistic electrons are undergoing stochastic 2nd-order Fermi acceleration by plasma wave turbulence through the entire volume of the bubbles. The observed gamma-ray spectral shape is then explained naturally by the resulting hard electron spectrum modulated by inverse-Compton energy losses. Rather than a constant volume emissivity as in other models, we predict a nearly constant surface brightness, and reproduce the observed sharp edges of the bubbles.

Authors: Mertsch, P; Sarkar, S

• Publication status: Published
• Journal: Physical Review Letters
• Volume: 107
• Issue: 9
• Pages: 091101
• Publication date: 2011-08-01
• DOI: 10.1103/physrevlett.107.091101
• EISSN: 1079-7114
• ISSN: 0031-9007
• Language: English
• Keywords: astro-ph.GA; astro-ph.HE; astro-ph.CO