VERITAS Search for VHE Gamma-ray Emission from Dwarf Spheroidal Galaxies
Abstract
Indirect dark matter searches with ground-based gamma-ray observatories provide an alternative for identifying the particle nature of dark matter that is complementary to that of direct search or accelerator production experiments. We present the results of observations of the dwarf spheroidal galaxies Draco, Ursa Minor, Bootes 1, and Willman 1 conducted by VERITAS. These galaxies are nearby dark matter dominated objects located at a typical distance of several tens of kiloparsecs for which there are good measurements of the dark matter density profile from stellar velocity measurements. Since the conventional astrophysical background of very high energy gamma rays from these objects appears to be negligible, they are good targets to search for the secondary gamma-ray photons produced by interacting or decaying dark matter particles. No significant gamma-ray flux above 200 GeV was detected from these four dwarf galaxies for a typical exposure of ~20 hours. The 95% confidence upper limits on the integral gamma-ray flux are in the range 0.4-2.2x10^-12 photons cm^-2s^-1. We interpret this limiting flux in the context of pair annihilation of weakly interacting massive particles and derive constraints on the thermally averaged product of the total self-annihilation cross section and the relative velocity of the WIMPs. The limits are obtained under conservative assumptions regarding the dark matter distribution in dwarf galaxies and are approximately three orders of magnitude above the generic theoretical prediction for WIMPs in the minimal supersymmetric standard model framework. However significant uncertainty exists in the dark matter distribution as well as the neutralino cross sections which under favorable assumptions could further lower the limits.
Keywords
Cite
@article{arxiv.1006.5955,
title = {VERITAS Search for VHE Gamma-ray Emission from Dwarf Spheroidal Galaxies},
author = {The VERITAS Collaboration and V. A. Acciari and T. Arlen and T. Aune and M. Beilicke and W. Benbow and D. Boltuch and S. M. Bradbury and J. H. Buckley and V. Bugaev and K. Byrum and A. Cannon and A. Cesarini and J. L. Christiansen and L. Ciupik and W. Cui and R. Dickherber and C. Duke and J. P. Finley and G. Finnegan and A. Furniss and N. Galante and S. Godambe and J. Grube and R. Guenette and G. Gyuk and D. Hanna and J. Holder and C. M. Hui and T. B. Humensky and A. Imran and P. Kaaret and N. Karlsson and M. Kertzman and D. Kieda and A. Konopelko and H. Krawczynski and F. Krennrich and G. Maier and S. McArthur and A. McCann and M. McCutcheon and P. Moriarty and R. A. Ong and A. N. Otte and D. Pandel and J. S. Perkins and M. Pohl and J. Quinn and K. Ragan and L. C. Reyes and P. T. Reynolds and E. Roache and H. J. Rose and M. Schroedter and G. H. Sembroski and G. Demet Senturk and A. W. Smith and D. Steele and S. P. Swordy and G. Tešić and M. Theiling and S. Thibadeau and A. Varlotta and V. V. Vassiliev and S. Vincent and R. G. Wagner and S. P. Wakely and J. E. Ward and T. C. Weekes and A. Weinstein and T. Weisgarber and D. A. Williams and S. Wissel and M. D. Wood and B. Zitzer},
journal= {arXiv preprint arXiv:1006.5955},
year = {2015}
}
Comments
21 pages, 2 figures, updated to reflect version published in ApJ. NOTE: M.D. Wood added as author