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Title: OBSERVATIONS OF MILKY WAY DWARF SPHEROIDAL GALAXIES WITH THE FERMI-LARGE AREA TELESCOPE DETECTOR AND CONSTRAINTS ON DARK MATTER MODELS

Abstract

We report on the observations of 14 dwarf spheroidal galaxies (dSphs) with the Fermi Gamma-Ray Space Telescope taken during the first 11 months of survey mode operations. The Fermi telescope, which is conducting an all-sky gamma-ray survey in the 20 MeV to >300 GeV energy range, provides a new opportunity to test particle dark matter models through the expected gamma-ray emission produced by pair annihilation of weakly interacting massive particles (WIMPs). Local Group dSphs, the largest galactic substructures predicted by the cold dark matter scenario, are attractive targets for such indirect searches for dark matter because they are nearby and among the most extreme dark matter dominated environments. No significant gamma-ray emission was detected above 100 MeV from the candidate dwarf galaxies. We determine upper limits to the gamma-ray flux assuming both power-law spectra and representative spectra from WIMP annihilation. The resulting {integral} flux above 100 MeV is constrained to be at a level below around 10{sup -9} photons cm{sup -2} s{sup -1}. Using recent stellar kinematic data, the gamma-ray flux limits are combined with improved determinations of the dark matter density profile in eight of the 14 candidate dwarfs to place limits on the pair-annihilation cross section of WIMPsmore » in several widely studied extensions of the standard model, including its supersymmetric extension and other models that received recent attention. With the present data, we are able to rule out large parts of the parameter space where the thermal relic density is below the observed cosmological dark matter density and WIMPs (neutralinos here) are dominantly produced non-thermally, e.g., in models where supersymmetry breaking occurs via anomaly mediation. The gamma-ray limits presented here also constrain some WIMP models proposed to explain the Fermi and PAMELA e {sup +} e {sup -} data, including low-mass wino-like neutralinos and models with TeV masses pair annihilating into muon-antimuon pairs.« less

Authors:
 [1]; ; ; ; ; ;  [2];  [3]; ; ; ;  [4];  [5];  [6];  [7];  [8];  [9];  [10];  [11];  [12]
  1. Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)
  2. W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
  3. Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States)
  4. Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
  5. Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France)
  6. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy)
  7. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
  8. Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy)
  9. Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy)
  10. Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France)
  11. Department of Physics, University of Washington, Seattle, WA 98195-1560 (United States)
  12. Dipartimento di Fisica 'G. Galilei', Universita di Padova, I-35131 Padova (Italy)
Publication Date:
OSTI Identifier:
21394279
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 712; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/712/1/147; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANNIHILATION; COSMIC MUONS; COSMIC PHOTONS; CROSS SECTIONS; GAMMA RADIATION; GEV RANGE; MASS; MEV RANGE; MILKY WAY; MUONS PLUS; NONLUMINOUS MATTER; PHOTON EMISSION; STANDARD MODEL; SUPERSYMMETRY; SYMMETRY BREAKING; TELESCOPES; TEST PARTICLES; TEV RANGE; ANTILEPTONS; ANTIMATTER; ANTIPARTICLES; BOSONS; COSMIC RADIATION; ELECTROMAGNETIC RADIATION; ELEMENTARY PARTICLES; EMISSION; ENERGY RANGE; FERMIONS; FIELD THEORIES; GALAXIES; GRAND UNIFIED THEORY; INTERACTIONS; IONIZING RADIATIONS; LEPTONS; MASSLESS PARTICLES; MATHEMATICAL MODELS; MATTER; MUONS; PARTICLE INTERACTIONS; PARTICLE MODELS; PHOTONS; QUANTUM FIELD THEORY; RADIATIONS; SECONDARY COSMIC RADIATION; SYMMETRY; UNIFIED GAUGE MODELS

Citation Formats

Abdo, A A, Ackermann, M, Ajello, M, Bechtol, K, Berenji, B, Bloom, E D, Borgland, A W, Atwood, W B, Baldini, L, Bellazzini, R, Bregeon, J, Brez, A, Ballet, J, Barbiellini, G, Bastieri, D, Bonamente, E, Brigida, M, Bruel, P, Burnett, T H, and Buson, S. OBSERVATIONS OF MILKY WAY DWARF SPHEROIDAL GALAXIES WITH THE FERMI-LARGE AREA TELESCOPE DETECTOR AND CONSTRAINTS ON DARK MATTER MODELS. United States: N. p., 2010. Web. doi:10.1088/0004-637X/712/1/147.
Abdo, A A, Ackermann, M, Ajello, M, Bechtol, K, Berenji, B, Bloom, E D, Borgland, A W, Atwood, W B, Baldini, L, Bellazzini, R, Bregeon, J, Brez, A, Ballet, J, Barbiellini, G, Bastieri, D, Bonamente, E, Brigida, M, Bruel, P, Burnett, T H, & Buson, S. OBSERVATIONS OF MILKY WAY DWARF SPHEROIDAL GALAXIES WITH THE FERMI-LARGE AREA TELESCOPE DETECTOR AND CONSTRAINTS ON DARK MATTER MODELS. United States. https://doi.org/10.1088/0004-637X/712/1/147
Abdo, A A, Ackermann, M, Ajello, M, Bechtol, K, Berenji, B, Bloom, E D, Borgland, A W, Atwood, W B, Baldini, L, Bellazzini, R, Bregeon, J, Brez, A, Ballet, J, Barbiellini, G, Bastieri, D, Bonamente, E, Brigida, M, Bruel, P, Burnett, T H, and Buson, S. Sat . "OBSERVATIONS OF MILKY WAY DWARF SPHEROIDAL GALAXIES WITH THE FERMI-LARGE AREA TELESCOPE DETECTOR AND CONSTRAINTS ON DARK MATTER MODELS". United States. https://doi.org/10.1088/0004-637X/712/1/147.
@article{osti_21394279,
title = {OBSERVATIONS OF MILKY WAY DWARF SPHEROIDAL GALAXIES WITH THE FERMI-LARGE AREA TELESCOPE DETECTOR AND CONSTRAINTS ON DARK MATTER MODELS},
author = {Abdo, A A and Ackermann, M and Ajello, M and Bechtol, K and Berenji, B and Bloom, E D and Borgland, A W and Atwood, W B and Baldini, L and Bellazzini, R and Bregeon, J and Brez, A and Ballet, J and Barbiellini, G and Bastieri, D and Bonamente, E and Brigida, M and Bruel, P and Burnett, T H and Buson, S},
abstractNote = {We report on the observations of 14 dwarf spheroidal galaxies (dSphs) with the Fermi Gamma-Ray Space Telescope taken during the first 11 months of survey mode operations. The Fermi telescope, which is conducting an all-sky gamma-ray survey in the 20 MeV to >300 GeV energy range, provides a new opportunity to test particle dark matter models through the expected gamma-ray emission produced by pair annihilation of weakly interacting massive particles (WIMPs). Local Group dSphs, the largest galactic substructures predicted by the cold dark matter scenario, are attractive targets for such indirect searches for dark matter because they are nearby and among the most extreme dark matter dominated environments. No significant gamma-ray emission was detected above 100 MeV from the candidate dwarf galaxies. We determine upper limits to the gamma-ray flux assuming both power-law spectra and representative spectra from WIMP annihilation. The resulting {integral} flux above 100 MeV is constrained to be at a level below around 10{sup -9} photons cm{sup -2} s{sup -1}. Using recent stellar kinematic data, the gamma-ray flux limits are combined with improved determinations of the dark matter density profile in eight of the 14 candidate dwarfs to place limits on the pair-annihilation cross section of WIMPs in several widely studied extensions of the standard model, including its supersymmetric extension and other models that received recent attention. With the present data, we are able to rule out large parts of the parameter space where the thermal relic density is below the observed cosmological dark matter density and WIMPs (neutralinos here) are dominantly produced non-thermally, e.g., in models where supersymmetry breaking occurs via anomaly mediation. The gamma-ray limits presented here also constrain some WIMP models proposed to explain the Fermi and PAMELA e {sup +} e {sup -} data, including low-mass wino-like neutralinos and models with TeV masses pair annihilating into muon-antimuon pairs.},
doi = {10.1088/0004-637X/712/1/147},
url = {https://www.osti.gov/biblio/21394279}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 712,
place = {United States},
year = {2010},
month = {3}
}