FERMI GAMMA-RAY HAZE VIA DARK MATTER AND MILLISECOND PULSARS

Journal Article · Wed Oct 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/722/2/1939· OSTI ID:21464581

Malyshev, Dmitry; Cholis, Ilias

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 {sup +} W {sup -}, b b-bar , and e {sup +} e {sup -}. 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 {sup +} e {sup -} 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 {approx}(2-6) x 10{sup 4} 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 {sup +} e {sup -} flux or the DM annihilates predominantly into leptons with a boost factor of order 100.

• OSTI ID: 21464581
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 722; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANISOTROPY
ANNIHILATION
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
ASTROPHYSICS
BASIC INTERACTIONS
BINARY STARS
BOSONS
COMPTON EFFECT
COSMIC RADIATION
COSMIC RADIO SOURCES
ELASTIC SCATTERING
ELECTROMAGNETIC INTERACTIONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
EMISSION
ENERGY RANGE
ERUPTIVE VARIABLE STARS
FERMIONS
GALAXIES
GAMMA RADIATION
GEV RANGE
GEV RANGE 10-100
INTERACTIONS
IONIZING RADIATIONS
LEPTONS
MASSLESS PARTICLES
MATTER
MILKY WAY
NONLUMINOUS MATTER
PARTICLE INTERACTIONS
PHOTON EMISSION
PHOTONS
PHYSICS
POSITRONS
PULSARS
RADIATIONS
SCATTERING
STARS
SUPERNOVAE
VARIABLE STARS