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Title: Dark matter annihilation rates with velocity-dependent annihilation cross sections

Abstract

The detection of by-products from particle annihilations in galactic halos would provide important information about the nature of the dark matter. Observational evidence for a local excess of high-energy positrons has motivated recent models with an additional interaction between dark matter particles that can result in a Sommerfeld enhancement to the cross section. In such models, the cross section for annihilation becomes velocity-dependent and may enhance the dark matter annihilation rate in the solar neighborhood relative to the rate in the early Universe sufficiently to source observed fluxes of high-energy positrons. We demonstrate that, for particle interaction cross sections that increase with decreasing velocity, the kinematical structures of dark matter halos with interior density profiles shallower than isothermal, such as Navarro-Frenk-White or Einasto halos, may induce a further enhancement owing to the position-dependent velocity distribution. We provide specific examples for the increase in the annihilation rate with a cross section enhanced by the Sommerfeld effect. In dark matter halos like that of the Milky Way and Local Group dwarf galaxies, the effective cross section at the halo center can be significantly larger than its local value. The additional enhancement owing to halo kinematics depends upon the parameters of any model,more » but is a prediction of certain models aimed at explaining measured positron fluxes and can exceed an order of magnitude.« less

Authors:
 [1];  [2]
  1. Kavli Institute for Cosmological Physics, and Department of Astronomy and Astrophysics, University of Chicago, 933 East 56th Street, Chicago, Illinois 60637 (United States)
  2. Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)
Publication Date:
OSTI Identifier:
21308282
Resource Type:
Journal Article
Journal Name:
Physical Review. D, Particles Fields
Additional Journal Information:
Journal Volume: 79; Journal Issue: 8; Other Information: DOI: 10.1103/PhysRevD.79.083525; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2821
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANNIHILATION; BY-PRODUCTS; CROSS SECTIONS; DENSITY; DETECTION; DISTRIBUTION; FORECASTING; MILKY WAY; NONLUMINOUS MATTER; PARTICLES; POSITRONS; UNIVERSE; VELOCITY

Citation Formats

Robertson, Brant E, Enrico Fermi Institute, 5640 South Ellis Avenue, Chicago, Illinois 60637, and Zentner, Andrew R. Dark matter annihilation rates with velocity-dependent annihilation cross sections. United States: N. p., 2009. Web. doi:10.1103/PHYSREVD.79.083525.
Robertson, Brant E, Enrico Fermi Institute, 5640 South Ellis Avenue, Chicago, Illinois 60637, & Zentner, Andrew R. Dark matter annihilation rates with velocity-dependent annihilation cross sections. United States. https://doi.org/10.1103/PHYSREVD.79.083525
Robertson, Brant E, Enrico Fermi Institute, 5640 South Ellis Avenue, Chicago, Illinois 60637, and Zentner, Andrew R. 2009. "Dark matter annihilation rates with velocity-dependent annihilation cross sections". United States. https://doi.org/10.1103/PHYSREVD.79.083525.
@article{osti_21308282,
title = {Dark matter annihilation rates with velocity-dependent annihilation cross sections},
author = {Robertson, Brant E and Enrico Fermi Institute, 5640 South Ellis Avenue, Chicago, Illinois 60637 and Zentner, Andrew R},
abstractNote = {The detection of by-products from particle annihilations in galactic halos would provide important information about the nature of the dark matter. Observational evidence for a local excess of high-energy positrons has motivated recent models with an additional interaction between dark matter particles that can result in a Sommerfeld enhancement to the cross section. In such models, the cross section for annihilation becomes velocity-dependent and may enhance the dark matter annihilation rate in the solar neighborhood relative to the rate in the early Universe sufficiently to source observed fluxes of high-energy positrons. We demonstrate that, for particle interaction cross sections that increase with decreasing velocity, the kinematical structures of dark matter halos with interior density profiles shallower than isothermal, such as Navarro-Frenk-White or Einasto halos, may induce a further enhancement owing to the position-dependent velocity distribution. We provide specific examples for the increase in the annihilation rate with a cross section enhanced by the Sommerfeld effect. In dark matter halos like that of the Milky Way and Local Group dwarf galaxies, the effective cross section at the halo center can be significantly larger than its local value. The additional enhancement owing to halo kinematics depends upon the parameters of any model, but is a prediction of certain models aimed at explaining measured positron fluxes and can exceed an order of magnitude.},
doi = {10.1103/PHYSREVD.79.083525},
url = {https://www.osti.gov/biblio/21308282}, journal = {Physical Review. D, Particles Fields},
issn = {0556-2821},
number = 8,
volume = 79,
place = {United States},
year = {Wed Apr 15 00:00:00 EDT 2009},
month = {Wed Apr 15 00:00:00 EDT 2009}
}