The Velocity-Dependent $J$-factor of the Milky Way Halo: Does What Happens in the Galactic Bulge Stay in the Galactic Bulge?

Abstract

We consider the angular distribution of the photon signal which could arise from velocity-dependent dark matter annihilation within the Galactic bulge. We find that, for the case of Sommerfeld-enhanced annihilation, dark matter annihilation within the bulge is dominated by slow speed particles which never leave the bulge, allowing one to find a simple analytic relationship between the dark matter profile within the Galactic bulge and the angular distribution. On the other hand, for the case $p$- or $d$-wave annihilation, we find that the small fraction of high-speed particles which can leave the bulge provide a significant, often dominant, contribution to dark matter annihilation within the bulge. For these scenarios, fully understanding dark matter annihilation deep within the Galactic bulge, and the angular distribution of the resulting photon signal, requires an understanding of the dark matter profile well outside the bulge. We consider the Galactic Center excess in light of these results, and find that an explanation of this excess in terms of $p$-wave annihilation would require the dark matter profile within the bulge to have a much steeper profile than usually considered, but with uncertainties related to the behavior of the profile outside the bulge.

arXiv comment17 pages, 3 figures, LaTeX, updated to match journal version

References in corpus (33)

• A Theory of Dark Matter
• Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi-LAT Data
• Dark Matter Annihilation in The Galactic Center As Seen by the Fermi Gamma Ray Space Telescope
• Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope
• Searching for Dark Matter Annihilation in Recently Discovered Milky Way Satellites with Fermi-LAT
• Dark Matter Constraints from Observations of 25 Milky Way Satellite Galaxies with the Fermi Large Area Telescope
• Background model systematics for the Fermi GeV excess
• Fermi-LAT Observations of High-Energy Gamma-Ray Emission Toward the Galactic Center
• Observations of Milky Way Dwarf Spheroidal galaxies with the Fermi-LAT detector and constraints on Dark Matter models
• Sommerfeld Enhancements for Thermal Relic Dark Matter
• Possible Evidence For Dark Matter Annihilation In The Inner Milky Way From The Fermi Gamma Ray Space Telescope
• The Consistency of Fermi-LAT Observations of the Galactic Center with a Millisecond Pulsar Population in the Central Stellar Cluster
• Matrix element analyses of dark matter scattering and annihilation
• Scalar Dark Matter Models with Significant Internal Bremsstrahlung
• Internal Bremsstrahlung Signature of Real Scalar Dark Matter and Consistency with Thermal Relic Density
• Dark Matter Annihilation Rates with Velocity-Dependent Annihilation Cross Sections
• Reconstructing WIMP Properties in Direct Detection Experiments Including Galactic Dark Matter Distribution Uncertainties
• Anatomy of Eddington-like inversion methods in the context of dark matter searches
• Sommerfeld-Enhanced $J$-Factors For Dwarf Spheroidal Galaxies
• The impact of the phase-space density on the indirect detection of dark matter
• A Search for Dark Matter Annihilation in the Milky Way Halo
• Taming astrophysical bias in direct dark matter searches
• A black hole window into p-wave dark matter annihilation
• On velocity-dependent dark matter annihilations in dwarf satellites
• The Effective J-Factor of the Galactic Center for Velocity-Dependent Dark Matter Annihilation
• Search for gamma-ray emission from $p$-wave dark matter annihilation in the Galactic Center
• Amplified J-factors in the Galactic Center for velocity-dependent darkmatter annihilation in FIRE simulations
• Velocity-dependent J-factors for annihilation radiation from cosmological simulations
• Constraint on the velocity dependent dark matter annihilation cross section from gamma-ray and kinematic observations of ultrafaint dwarf galaxies
• A Systematic Study of Hidden Sector Dark Matter: Application to the Gamma-Ray and Antiproton Excesses
• Angular distribution of gamma-ray emission from velocity-dependent dark matter annihilation in subhalos
• Black Holes, Dark Matter Spikes, and Constraints on Simplified Models with $t$-Channel Mediators
• $J$-factors for Velocity-dependent Dark Matter

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