Multi-wavelength Emission from the Fermi Bubble III. Stochastic (Fermi) Re-Acceleration of Relativistic Electrons Emitted by SNRs

Abstract

We analyse the model of stochastic re-acceleration of electrons, which are emitted by supernova remnants (SNRs) in the Galactic Disk and propagate then into the Galactic halo, in order to explain the origin on nonthermal (radio and gamma-ray) emission from the Fermi Bubbles (FB). We assume that the energy for re-acceleration in the halo is supplied by shocks generated by processes of star accretion onto the central black hole. Numerical simulations show that regions with strong turbulence (places for electron re-acceleration) are located high up in the Galactic Halo about several kpc above the disk. The energy of SNR electrons that reach these regions does not exceed several GeV because of synchrotron and inverse Compton energy losses. At appropriate parameters of re-acceleration these electrons can be re-accelerated up to the energy 10E12 eV which explains in this model the origin of the observed radio and gamma-ray emission from the FB. However although the model gamma-ray spectrum is consistent with the Fermi results, the model radio spectrum is steeper than the observed by WMAP and Planck. If adiabatic losses due to plasma outflow from the Galactic central regions are taken into account, then the re-acceleration model nicely reproduces the Planck datapoints.

33 pages, 8 figures, accepted by ApJ

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Cited by in corpus (6)

• The Interaction of the Fermi Bubbles with the Milky Way's Hot Gas Halo
• Simulating the Fermi Bubbles as Forward Shocks Driven by AGN Jets
• The Important Role of Cosmic-Ray Re-Acceleration
• Sources and Radiations of the Fermi Bubbles
• Cosmic Ray (Stochastic) Acceleration from a Background Plasma
• On the high-energy protons regular acceleration in the Fermi Bubbles