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Title: Confronting various dark matter scenarios with dwarf spheroidal gamma-ray observations

Abstract

Dwarf spheroidal galaxies are promising targets for the indirect detection of dark matter through gamma-ray emission due to their proximity, lack of astrophysical backgrounds and high dark matter density. They are often used to place restrictive bounds on the dark matter annihilation cross section. In this report, we analyze six years of Fermi-LAT gamma-ray data from Dwarf Spheroidal galaxies that are satellites of the Milky Way, and constrain the parameter space that explain the Fermi-LAT Galactic center gamma-ray emission in 4 body final states, neutralino dark matter annihilation cross-section, and decaying dark matter lifetime for several decay channels.

Authors:
 [1]
  1. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242 (United States)
Publication Date:
OSTI Identifier:
22609063
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1743; Journal Issue: 1; Conference: CETUP 2015: Workshop on dark matter, neutrino physics and astrophysics, Deadwood, SD (United States), 15 Jun - 17 Jul 2015, PPC 2015: 9. international conference on interconnections between particle physics and cosmology, Deadwood, SD (United States), 15 Jun - 17 Jul 2015; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANNIHILATION; ASTROPHYSICS; COSMIC GAMMA SOURCES; CROSS SECTIONS; DECAY; DENSITY; DETECTION; DWARF STARS; EMISSION; GAMMA RADIATION; LIFETIME; MILKY WAY; NEUTRALINOS; NONLUMINOUS MATTER; SPACE

Citation Formats

Ghosh, Tathagata, E-mail: ghoshtatha@tamu.edu. Confronting various dark matter scenarios with dwarf spheroidal gamma-ray observations. United States: N. p., 2016. Web. doi:10.1063/1.4953272.
Ghosh, Tathagata, E-mail: ghoshtatha@tamu.edu. Confronting various dark matter scenarios with dwarf spheroidal gamma-ray observations. United States. doi:10.1063/1.4953272.
Ghosh, Tathagata, E-mail: ghoshtatha@tamu.edu. Tue . "Confronting various dark matter scenarios with dwarf spheroidal gamma-ray observations". United States. doi:10.1063/1.4953272.
@article{osti_22609063,
title = {Confronting various dark matter scenarios with dwarf spheroidal gamma-ray observations},
author = {Ghosh, Tathagata, E-mail: ghoshtatha@tamu.edu},
abstractNote = {Dwarf spheroidal galaxies are promising targets for the indirect detection of dark matter through gamma-ray emission due to their proximity, lack of astrophysical backgrounds and high dark matter density. They are often used to place restrictive bounds on the dark matter annihilation cross section. In this report, we analyze six years of Fermi-LAT gamma-ray data from Dwarf Spheroidal galaxies that are satellites of the Milky Way, and constrain the parameter space that explain the Fermi-LAT Galactic center gamma-ray emission in 4 body final states, neutralino dark matter annihilation cross-section, and decaying dark matter lifetime for several decay channels.},
doi = {10.1063/1.4953272},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1743,
place = {United States},
year = {Tue Jun 21 00:00:00 EDT 2016},
month = {Tue Jun 21 00:00:00 EDT 2016}
}
  • Cited by 13
  • We present a new analysis of the relative detectability of dark matter annihilation in the Milky Way's eight 'classical' dwarf spheroidal (dSph) satellite galaxies. Ours is similar to previous analyses in that we use Markov-Chain Monte Carlo techniques to fit dark matter halo parameters to empirical velocity dispersion profiles via the spherical Jeans equation, but more general in the sense that we do not adopt priors derived from cosmological simulations. We show that even without strong constraints on the shapes of dSph dark matter density profiles (we require only that the inner profile satisfies -liM{sub r {yields} 0} dln {rho}/dlnmore » r {<=} 1), we obtain a robust and accurate constraint on the astrophysical component of a prospective dark matter annihilation signal, provided that the integration angle is approximately twice the projected half-light radius of the dSph divided by distance to the observer, {alpha}{sub int} {approx} 2r{sub h} /d. Using this integration angle, which represents a compromise between maximizing prospective flux and minimizing uncertainty in the dSph's dark matter distribution, we calculate the relative detectability of the classical dSphs by ground- and space-based {gamma}-ray observatories.« less
  • Cited by 21
  • The Fermi-LAT Collaboration has studied the gamma-ray emission from a stacked population of dwarf spheroidal galaxies and used this information to set constraints on the dark matter annihilation cross section. Interestingly, their analysis uncovered an excess with a test statistic (TS) of 8.7. If interpreted naively, this constitutes a 2.95σ local excess (p-value=0.003), relative to the expectations of their background model. In order to further test this interpretation, the Fermi-LAT team studied a large number of blank sky locations and found TS>8.7 excesses to be more common than predicted by their background model, decreasing the significance of their dwarf excessmore » to 2.2σ(p-value=0.027). We argue that these TS>8.7 blank sky locations are largely the result of unresolved blazars, radio galaxies, and star-forming galaxies, and show that multiwavelength information can be used to reduce the degree to which such sources contaminate the otherwise blank sky. In particular, we show that masking regions of the sky that lie within 1° of sources contained in the BZCAT or CRATES catalogs reduce the fraction of blank sky locations with TS>8.7 by more than a factor of 2. Taking such multiwavelength information into account can enable experiments such as Fermi to better characterize their backgrounds and increase their sensitivity to dark matter in dwarf galaxies, the most important of which remain largely uncontaminated by unresolved point sources. We also note that for the range of dark matter masses and annihilation cross sections currently being tested by studies of dwarf spheroidal galaxies, simulations predict that Fermi should be able to detect a significant number of dark matter subhalos. These subhalos constitute a population of subthreshold gamma-ray point sources and represent an irreducible background for searches for dark matter annihilation in dwarf galaxies.« less