2010ApJ...722.1939M -
Astrophys. J., 722, 1939-1945 (2010/October-3)
Fermi gamma-ray haze via dark matter and millisecond pulsars.
MALYSHEV D., CHOLIS I. and GELFAND J.D.
Abstract (from CDS):
We study possible astrophysical and dark matter (DM) explanations for the Fermi gamma-ray haze in the Milky Way halo. As representatives of various DM models, we consider DM particles annihilating into W + W –, and e + e –. In the first two cases, the prompt gamma-ray emission from DM annihilations is significant or even dominant at E > 10 GeV, while inverse Compton scattering (ICS) from annihilating DM products is insignificant. For the e + e – annihilation mode, we require a boost factor of order 100 to get significant contribution to the gamma-ray haze from ICS photons. Possible astrophysical sources of high-energy particles at high latitudes include type Ia supernovae (SNe) and millisecond pulsars (MSPs). Based on our current understanding of Ia SNe rates, they do not contribute significantly to gamma-ray flux in the halo of the Milky Way. As the MSP population in the stellar halo of the Milky Way is not well constrained, MSPs may be a viable source of gamma-rays at high latitudes provided that there are ~(2-6) x104 of MSPs in the Milky Way stellar halo. In this case, pulsed gamma-ray emission from MSPs can contribute to gamma rays around few GeV, while the ICS photons from MSP electrons and positrons may be significant at all energies in the gamma-ray haze. The plausibility of such a population of MSPs is discussed. Consistency with the Wilkinson Microwave Anisotropy Probe (WMAP) microwave haze requires that either a significant fraction of MSP spin-down energy is converted into e + e – flux or the DM annihilates predominantly into leptons with a boost factor of order 100.
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Journal keyword(s):
cosmic rays - dark matter - Galaxy: halo - gamma rays: diffuse background - pulsars: general
Simbad objects:
7
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