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 γ-ray survey in the 20 MeV to >300 GeV energy range, provides a new opportunity to test particle dark matter models through the expected γ-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 γ-ray emission was detected above 100 MeV from the candidate dwarf galaxies. We determine upper limits to the γ-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 γ-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 γ-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.
|Autori:||Abdo AA; Ackermann M; Ajello M; Atwood WB; Baldini L; Ballet J; Barbiellini G; Bastieri D; Bechtol K; Bellazzini R; Berenji B; Bloom ED; Bonamente E; Borgland AW; Bregeon J; Brez A; Brigida M; Bruel P; Burnett TH; Buson S; Caliandro GA; Cameron RA; Caraveo PA; Casandjian JM; Cecchi C; Chekhtman A; Cheung CC; Chiang J; Ciprini S; Claus R; Cohen-Tanugi J; Conrad J; de Angelis A; de Palma F; Digel SW; Silva EDE; Drell PS; Drlica-Wagner A; Dubois R; Dumora D; Farnier C; Favuzzi C; Fegan SJ; Focke WB; Fortin P; Frailis M; Fukazawa Y; Fusco P; Gargano F; Gehrels N; Germani S; Giebels B; Giglietto N; Giordano F; Glanzman T; Godfrey G; Grenier IA; Grove JE; Guillemot L; Guiriec S; Gustafsson M; Harding AK; Hays E; Horan D; Hughes RE; Jackson MS; Jeltema TE; Johannesson G; Johnson AS; Johnson RP; Johnson WN; Kamae T; Katagiri H; Kataoka J; Kerr M; Knodlseder J; Kuss M; Lande J; Latronico L; Lemoine-Goumard M; Longo F; Loparco F; Lott B; Lovellette MN; Lubrano P; Madejski GM; Makeev A; Mazziotta MN; McEnery JE; Meurer C; Michelson PF; Mitthumsiri W; Mizuno T; Moiseev AA; Monte C; Monzani ME; Moretti E; Morselli A; Moskalenko IV; Murgia S; Nolan PL; Norris JP; Nuss E; Ohsugi T; Omodei N; Orlando E; Ormes JF; Paneque D; Panetta JH; Parent D; Pelassa V; Pepe M; Pesce-Rollins M; Piron F; Porter TA; Profumo S; Raino S; Rando R; Razzano M; Reimer A; Reimer O; Reposeur T; Ritz S; Rodriguez AY; Roth M; Sadrozinski HFW; Sander A; Parkinson PMS; Scargle JD; Schalk TL; Sellerholm A; Sgro C; Siskind EJ; Smith DA; Smith PD; Spandre G; Spinelli P; Strickman MS; Suson DJ; Takahashi H; Takahashi T; Tanaka T; Thayer JB; Thayer JG; Thompson DJ; Tibaldo L; Torres DF; Tramacere A; Uchiyama Y; Usher TL; Vasileiou V; Vilchez N; Vitale V; Waite AP; Wang P; Winer BL; Wood KS; Ylinen T; Ziegler M; Bullock JS; Kaplinghat M; Martinez GD|
|Titolo:||OBSERVATIONS OF MILKY WAY DWARF SPHEROIDAL GALAXIES WITH THE FERMI-LARGE AREA TELESCOPE DETECTOR AND CONSTRAINTS ON DARK MATTER MODELS|
|Anno del prodotto:||2010|
|Digital Object Identifier (DOI):||10.1088/0004-637X/712/1/147|
|Appare nelle tipologie:||1.1 Articolo in rivista|