2018/11/30 by A.U. Abeysekara, A. U. Abeysekara, A. Albert +98 · 1 citation
Physics and Astronomy · #Cherenkov radiation #Dark Matter and Cosmic Phenomena #Dark matter #Galaxy #Milky Way #Particle Detector Development and Performance #Radiation Detection and Scintillator Technologies #Scalar field dark matter #Sky #WIMP #astro-ph.HE
paper · pdf · doi:10.1088/1475-7516/2019/07/022
20 pages, 10 figures. submitted to JCAP
openalex created_date 2018/12/11 · arxiv created 2019/06/20 · openalex publication_date 2019/07/15 · arxiv updated 2019/07/24 · openalex updated_date 2026/08/05
Numerical simulations show that the dark matter halos surrounding galaxies are expected to contain many over-densities or sub-halos. The most massive of these sub-halos can be optically observed in the form of dwarf galaxies. However, most lower mass sub-halos are predicted to exist as dark dwarf galaxies: sub-halos like dwarf galaxies with no luminous counterpart. It may be possible to detect these unseen sub-halos from gamma-ray signals originating from dark matter annihilation. The High Altitude Water Cherenkov Observatory (HAWC) is a very high energy (500 GeV to >100 TeV) gamma ray detector with a wide field-of-view and near continuous duty cycle, making HAWC ideal for unbiased sky surveys. We perform a search for gamma ray signals from dark dwarfs in the Milky Way halo with HAWC. We perform a targeted search of HAWC gamma-ray sources which have no known association with lower-energy counterparts, based on an unbiased survey of the entire sky. With no sources found to strongly prefer dark matter models, we calculate the ability of HAWC to observe dark dwarfs. We also compute the HAWC sensitivity to potential future detections for a given model of dark matter substructure. Assuming thermal dark matter, we find the corresponding J-factor of a dark dwarf required to reach the HAWC detection criterion is 5.79 × 10 20 GeV 2 cm −5 sr for one particular set of dark matter assumptions. HAWC is found to be able to competitively constrain dark matter annihilation from discovered halos with J-factors on the scale of 10 19 GeV 2 cm −5 sr or greater, with better constraints obtained on dark matter models with >10 TeV masses and sources that transit overhead.