Effects of P-wave Annihilation on the Angular Power Spectrum of Extragalactic Gamma-rays from Dark Matter Annihilation

Abstract

We present a formalism for estimating the angular power spectrum of extragalactic gamma-rays produced by dark matter annihilating with any general velocity-dependent cross section. The relevant density and velocity distribution of dark matter is modeled as an ensemble of smooth, universal, rigid, disjoint, spherical halos with distribution and universal properties constrained by simulation data. We apply this formalism to theories of dark matter with p-wave annihilation, for which the relative-velocity-weighted annihilation cross section is σv=a+bv^2. We determine that this significantly increases the gamma-ray power if b/a >> 10^6. The effect of p-wave annihilation on the angular power spectrum is very similar for the sample of particle physics models we explored, suggesting that the important effect for a given b/a is largely determined by the cosmic dark matter distribution. If the dark matter relic from strong p-wave theories is thermally produced, the intensities of annihilation gamma-rays are strongly p-wave suppressed, making them difficult to observe. If an angular power spectrum consistent with a strong p-wave were to be observed, it would likely indicate non-thermal production of dark matter in the early Universe.

20 pages, 3 figures

References in corpus (18)

• Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Observation of an anomalous positron abundance in the cosmic radiation
• A Theory of Dark Matter
• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
• Relative velocity of dark matter and baryonic fluids and the formation of the first structures
• Fermi LAT observations of cosmic-ray electrons from 7 GeV to 1 TeV
• On possible interpretations of the high energy electron-positron spectrum measured by the Fermi Large Area Telescope
• Dark Matter Direct Detection with Non-Maxwellian Velocity Structure
• PAMELA Positron Excess as a Signal from the Hidden Sector
• Dark matter annihilation or unresolved astrophysical sources? Anisotropy probe of the origin of cosmic gamma-ray background
• A generalized local ansatz and its effect on halo bias
• Corrected Table for the Parametric Coefficients for the Optical Depth of the Universe to Gamma-rays at Various Redshifts
• Angular Signatures of Annihilating Dark Matter in the Cosmic Gamma-Ray Background
• Cosmic ray electrons and positrons from supernova explosions of massive stars
• Scale-dependent halo bias from scale-dependent growth
• Effects of Velocity-Dependent Dark Matter Annihilation on the Energy Spectrum of the Extragalactic Gamma-ray Background
• Hierarchy in the Phase Space and Dark Matter Astronomy

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• $\chi$aro$\nu$: a tool for neutrino flux generation from WIMPs
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