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

Journal Article · Sat Mar 20 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/712/1/147· OSTI ID:21394279

Abdo, A A ^[1]; Ackermann, M; Ajello, M; Bechtol, K; Berenji, B; Bloom, E D; Borgland, A W ^[2]; Atwood, W B ^[3]; Baldini, L; Bellazzini, R; Bregeon, J; Brez, A ^[4]; Ballet, J ^[5]; Barbiellini, G ^[6]; Bastieri, D ^[7]; Bonamente, E ^[8]; Brigida, M ^[9]; Bruel, P ^[10]; Burnett, T H ^[11]; Buson, S ^[12]

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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)

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.

• OSTI ID: 21394279
• Journal Information: Astrophysical Journal, Vol. 712, Issue 1; Other Information: DOI: 10.1088/0004-637X/712/1/147; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

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