Observations of Milky Way Dwarf Spheroidal Galaxies with the Fermi-Large Area Telescope Detector and Constraints on Dark Matter Models

• Published in: The Astrophysical journal Vol. 712; no. 1; pp. 147 - 158
• Main Authors: Ajello, M, Atwood, W. B, Baldini, L, Ballet, J, Bastieri, D, Bellazzini, R, Bonamente, E, Bregeon, J, Brez, A, Bruel, P, Cameron, R. A, Caraveo, P. A, Casandjian, J. M, Cheung, C. C, Chiang, J, Cohen-Tanugi, J, Digel, S. W, do Couto e Silva, E, Dumora, D, Favuzzi, C, Fegan, S. J, Focke, W. B, Fortin, P, Frailis, M, Fukazawa, Y, Fusco, P, Gargano, F, Gehrels, N, Germani, S, Giordano, F, Glanzman, T, Grenier, I. A, Grove, J. E, Guillemot, L, Guiriec, S, Gustafsson, M, Harding, A. K, Hays, E, Hughes, R. E, Jeltema, T. E, Johnson, A. S, Kamae, T, Kataoka, J, Lande, J, Lemoine-Goumard, M, Longo, F, Lott, B, Lovellette, M. N, Lubrano, P, Madejski, G. M, Makeev, A, Meurer, C, Michelson, P. F, Mizuno, T, Moiseev, A. A, Monte, C, Monzani, M. E, Moretti, E, Morselli, A, Moskalenko, I. V, Nolan, P. L, Nuss, E, Ohsugi, T, Omodei, N, Parent, D, Pepe, M, Pesce-Rollins, M, Piron, F, Porter, T. A, Profumo, S, Rainò, S, Rando, R, Razzano, M, Reimer, A, Reposeur, T, Rodriguez, A. Y, Sander, A, Scargle, J. D, Schalk, T. L, Sgrò, C, Siskind, E. J, Spinelli, P, Strickman, M. S, Suson, D. J, Takahashi, H, Takahashi, T, Tanaka, T, Thayer, J. B, Thayer, J. G, Tramacere, A, Usher, T. L, Vasileiou, V, Vilchez, N, Vitale, V, Waite, A. P, Wang, P, Winer, B. L, Wood, K. S, Bullock, James S, Kaplinghat, Manoj
• Format: Journal Article
• Language: English
• Published: United States IOP Publishing 20.03.2010
• Subjects: ANNIHILATION; ANTILEPTONS; ANTIMATTER; ANTIPARTICLES; Astronomi och astrofysik; Astronomy and astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BOSONS; COSMIC MUONS; COSMIC PHOTONS; COSMIC RADIATION; CROSS SECTIONS; dark matter; ELECTROMAGNETIC RADIATION; ELEMENTARY PARTICLES; EMISSION; ENERGY RANGE; FERMIONS; FIELD THEORIES; Fysik; GALAXIES; galaxies: dwarf; GAMMA RADIATION; gamma rays: galaxies; GEV RANGE; GRAND UNIFIED THEORY; INTERACTIONS; IONIZING RADIATIONS; LEPTONS; MASS; MASSLESS PARTICLES; MATHEMATICAL MODELS; MATTER; MEV RANGE; MILKY WAY; MUONS; MUONS PLUS; NATURAL SCIENCES; NATURVETENSKAP; NONLUMINOUS MATTER; PARTICLE INTERACTIONS; PARTICLE MODELS; PHOTON EMISSION; PHOTONS; Physics; QUANTUM FIELD THEORY; RADIATIONS; SECONDARY COSMIC RADIATION; STANDARD MODEL; SUPERSYMMETRY; SYMMETRY; SYMMETRY BREAKING; TELESCOPES; TEST PARTICLES; TEV RANGE; UNIFIED GAUGE MODELS
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.1088/0004-637X/712/1/147

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(-9) photons cm(-2) s(-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(+)e(-) data, including low-mass wino-like neutralinos and models with TeV masses pair annihilating into muon-antimuon pairs.