A search for a dark matter annihilation signal towards the Canis Major overdensity with H.E.S.S

F. Aharonian , A.G. Akhperjanian , U. Barres de Almeida , A.R. Bazer-Bachi (1) , B. Behera , M. Beilicke , W. Benbow , K. Bernlöhr , C. Boisson (2) , V. Borrel (1) , I. Braun , E. Brion (3) , J. Brucker , R. Bühler , T. Bulik , I. Büsching , T. Boutelier (4) , S. Carrigan , P.M. Chadwick , R. Chaves , L.-M. Chounet (5) , G. Coignet (6) , R. Cornils , L. Costamante , M. Dalton , B. Degrange (5) , H.J. Dickinson , A. Djannati-Ataï (7) , W. Domainko , L.O'C. Drury , F. Dubois (6) , G. Dubus (4) , J. Dyks , K. Egberts , D. Emmanoulopoulos , P. Espigat (8) , C. Farnier (9) , F. Feinstein (9) , A. Fiasson (3, 9) , A. Förster , G. Fontaine (5) , M. Füssling , S. Gabici , Y.A. Gallant (9) , L. Gérard (8) , B. Giebels (5) , J.F. Glicenstein (3) , B. Glück , P. Goret (3) , C. Hadjichristidis , D. Hauser , M. Hauser , G. Heinzelmann , G. Henri (4) , G. Hermann , J.A. Hinton , A. Hoffmann , W. Hofmann , M. Holleran , S. Hoppe , D. Horns , A. Jacholkowska (9) , O.C. de Jager , I. Jung , K. Katarzy'Nski , E. Kendziorra , M. Kerschhaggl , D. Khangulyan , B. Khélifi (5) , D. Keogh , Nu. Komin (9) , K. Kosack , G. Lamanna (6) , I.J. Latham , J.-P. Lenain (2) , T. Lohse , J.M. Martin (2) , O. Martineau-Huynh (10) , A. Marcowith (9) , C. Masterson , D. Maurin (10) , T.J.L. Mccomb , R. Moderski , Emmanuel Moulin (3) , M. Naumann-Godo (5) , M. de Naurois (10) , D. Nedbal , D. Nekrassov , S.J. Nolan , S. Ohm , J.-P. Olive (1) , E. de Oña Wilhelmi (8) , K.J. Orford , J.L. Osborne , M. Ostrowski , M. Panter , G. Pedaletti , G. Pelletier (4) , P.-O. Petrucci (4) , S. Pita (8) , G. Pühlhofer , M. Punch (8) , A. Quirrenbach , B.C. Raubenheimer , M. Raue , S.M. Rayner , M. Renaud , F. Rieger , J. Ripken , L. Rob , S. Rosier-Lees (6) , G. Rowell , B. Rudak , J. Ruppel , V. Sahakian , A. Santangelo , R. Schlickeiser , F.M. Scöck , R. Schröder , U. Schwanke , S. Schwarzburg , S. Schwemmer , A. Shalchi , H. Sol (2) , D. Spangler , L. Stawarz , R. Steenkamp , C. Stegmann , G. Superina (5) , P.H. Tam , J.-P. Tavernet (10) , R. Terrier (8) , V. Marandon (8) , C. van Eldik , G. Vasileiadis (9) , C. Venter , J.P. Vialle (6) , P. Vincent (10) , M. Vivier (3) , H.J. Völk , F. Volpe (5) , S.J. Wagner , M. Ward , A.A. Zdziarski , A. Zech (2)

1 CESR - Centre d'étude spatiale des rayonnements
2 LUTH (UMR_8102) - Laboratoire Univers et Théories
3 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
4 LAOG - Laboratoire d'Astrophysique de Grenoble
5 LLR - Laboratoire Leprince-Ringuet
6 LAPP - Laboratoire d'Annecy de Physique des Particules
7 APC - AHE - APC - Astrophysique des Hautes Energies
8 APC (UMR_7164) - AstroParticule et Cosmologie
9 LPTA - Laboratoire de Physique Théorique et Astroparticules
10 LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies

A search for a dark matter (DM) annihilation signal into $\gamma$-rays toward the direction of the Canis Major (CMa) overdensity is presented. The nature of CMa is still controversial and one scenario represents it as a dwarf galaxy, making it an interesting candidate for DM annihilation searches. A total of 9.6 hours of high quality data were collected with the H.E.S.S. array of Imaging Atmospheric Cherenkov Telescopes (IACTs) and no evidence for a very high energy $\gamma$-ray signal is found. Upper limits on the CMa dwarf galaxy mass of the order of 10$^{9}$ M$_{\odot}$ are derived at the 95% C.L. assuming neutralino masses in the range 500 GeV - 10 TeV and relatively large annihilation cross-sections. Constraints on the velocity-weighted annihilation cross section $<\sigma v>$, are calculated for specific WIMP scenarios, using a NFW model for the DM halo profile and taking advantage of numerical simulations of hierarchical structure formation. 95% C.L. exclusion limits of the order of 5 $\times$ 10$^{-24}$ cm$^{3}$ s$^{-1}$ are reached in the 500 GeV - 10 TeV DM particle mass interval, assuming a total halo mass of 3 $\times$ 10$^{8}$ M$_{\odot}$.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]

F. Aharonian, A.G. Akhperjanian, U. Barres de Almeida, A.R. Bazer-Bachi, B. Behera, et al.. A search for a dark matter annihilation signal towards the Canis Major overdensity with H.E.S.S. The Astrophysical Journal, 2009, 691, pp.175-181. ⟨10.1088/0004-637X/691/1/175⟩. ⟨in2p3-00324687⟩