Relatore
Dr.
Philipp Mertsch
(Rudolf Peierls Centre for Theoretical Physics)
Descrizione
Gamma-ray data from Fermi-LAT reveal a bi-lobular structure extending up to 50 degrees above and below the galactic centre, which presumably originated in some form of energy release there less than a few million years ago. 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 and inverse Compton 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.
Autore principale
Dr.
Philipp Mertsch
(Rudolf Peierls Centre for Theoretical Physics)
Coautore
Prof.
Subir Sarkar
(Rudolf Peierls Centre for Theoretical Physics, University of Oxford)
