HESS very-high-energy gamma-ray sources without identified counterparts

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) , O. Bolz , V. Borrel (1) , I. Braun , E. Brion (3) , A.M. Brown , R. Bühler , T. Bulik , I. Büsching , T. Boutelier (4) , S. Carrigan , P.M. Chadwick , L.-M. Chounet (5) , A.C. Clapson , 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 (9) , A. Förster , G. Fontaine (5) , Seb. Funk , M. Füssling , Y.A. Gallant (9) , 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. Katarzynski , E. Kendziorra , M. Kerschhaggl , B. Khélifi (5) , D. Keogh , Nu. Komin (9) , K. Kosack , G. Lamanna (6) , I. J. Latham , A. Lemière (8) , M. Lemoine-Goumard (5) , J.-P. Lenain (2) , T. Lohse , J. M. Martin (2) , O. Martineau-Huynh (10) , A. Marcowith (9) , C. Masterson , D. Maurin (10) , G. Maurin (8) , T. J. L.Mccomb , R. Moderski , Emmanuel Moulin (3) , M. de Naurois (10) , D. Nedbal , 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) , S. Ranchon (6) , B.C. Raubenheimer , M. Raue , S.M. Rayner , M. Renaud , J. Ripken , L. Rob , L. Rolland (3) , S. Rosier-Lees (6) , G. Rowell , B. Rudak , J. Ruppel , V. Sahakian , A. Santangelo , R. Schlickeiser , F. Schöck , 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) , 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 , A.A. Zdziarski , A. Zech (2)

1 CESR - Centre d'étude spatiale des rayonnements
2 LUTH (UMR_8102) - Laboratoire Univers et Théories
3 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
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

Context.The detection of gamma rays in the very-high-energy (VHE) energy range (100 GeV-100 TeV) provides a direct view of the parent population of ultra-relativistic particles found in astrophysical sources. For this reason, VHE gamma rays are useful for understanding the underlying astrophysical processes in non-thermal sources. Aims.We investigate unidentified VHE gamma-ray sources that have been discovered with HESS in the most sensitive blind survey of the Galactic plane at VHE energies conducted so far. Methods.The HESS array of imaging atmospheric Cherenkov telescopes (IACTs) has a high sensitivity compared with previous instruments (~ in 25 h observation time for a point-source detection), and with its large field of view, is well suited for scan-based observations. The on-going HESS survey of the inner Galaxy has revealed a large number of new VHE sources, and for each we attempt to associate the VHE emission with multi-wavelength data in the radio through X-ray wavebands. Results. For each of the eight unidentified VHE sources considered here, we present the energy spectra and sky maps of the sources and their environment. The VHE morphology is compared with available multi-wavelength data (mainly radio and X-rays). No plausible counterparts are found.

Mots clés: gamma rays: observations; Galaxy: general; cosmic rays; surveys

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.. HESS very-high-energy gamma-ray sources without identified counterparts. Astronomy and Astrophysics - A&A, 2008, 477, pp.353-363. ⟨10.1051/0004-6361:20078516⟩. ⟨in2p3-00196769⟩