Discovery of VHE emission towards the Carina arm region with the H.E.S.S. telescope array: HESS J1018-589

A. Abramowski , Fabio Acero (1) , F. Aharonian , A. G. Akhperjanian , G. Anton , Agnès Balzer , A. Barnacka , U. Barres de Almeida , Y. Becherini (2, 3) , J. Becker , B. Behera , K. Bernlöhr , E. Birsin , J. Biteau (2) , A. Bochow , C. Boisson , J. Bolmont , P. Bordas , J. Brucker , F. Brun (2) , P. Brun , T. Bulik , I. Büsching , S. Carrigan , S. Casanova , M. Cerruti , P. M. Chadwick , A. Charbonnier , R. C. G. Chaves , A. Cheesebrough , A. C. Clapson , G. Cologna , J. Conrad , M. Dalton , M. K. Daniel , I. D. Davids , B. Degrange (2) , C. Deil , H. J. Dickinson , A. Djannati-Ataï (4) , W. Domainko , L. O'C. Drury , G. Dubus , K. Dutson , J. Dyks , M. Dyrda , K. Egberts , P. Eger , P. Espigat (3) , L. Fallon , C. Farnier (1) , S. Fegan , F. Feinstein (1) , M. V. Fernandes , A. Fiasson (5) , F. Krayzel (5) , G. Fontaine (2) , A. Förster , M. Füssling , Y. A. Gallant (1) , H. Gast , L. Gérard (3) , D. Gerbig , B. Giebels (2) , J. F. Glicenstein , B. Glück , P. Goret , D. Göring , S. Häffner , J. D. Hague , D. Hampf , M. Hauser , S. Heinz , G. Heinzelmann , G. Henri , G. Hermann , J. A. Hinton , A. Hoffmann , W. Hofmann , P. Hofverberg , M. Holler , D. Horns , A. Jacholkowska , O. C. de Jager , C. Jahn , M. Jamrozy , I. Jung , M. A. Kastendieck , K. Katarzyński , U. Katz , S. Kaufmann , D. Keogh , D. Khangulyan , B. Khélifi (2) , D. Klochkov , W. Kluźniak , T. Kneiske , Nu. Komin (5) , K. Kosack , R. Kossakowski (5) , H. Laffon (2) , G. Lamanna (5) , D. Lennarz , T. Lohse , A. Lopatin , C. -C. Lu , V. Marandon , Alexandre Marcowith (1) , Julien Masbou (5) , D. Maurin , N. Maxted , M. Mayer , T. J. L. Mccomb , M. C. Medina , J. Méhault (6) , R. Moderski , Emmanuel Moulin , C. L. Naumann , M. Naumann-Godo , M. de Naurois (2) , D. Nedbal , D. Nekrassov , N. Nguyen , B. Nicholas , J. Niemiec , S. J. Nolan , S. Ohm , E. de Oña Wilhelmi , B. Opitz , M. Ostrowski , I. Oya , M. Panter , M. Paz Arribas , G. Pedaletti , G. Pelletier , P. -O. Petrucci , S. Pita (3) , G. Pühlhofer , M. Punch (3) , A. Quirrenbach , M. Raue , S. M. Rayner , A. Reimer , O. Reimer , Matthieu Renaud (1) , R. de Los Reyes , F. Rieger , J. Ripken , L. Rob , S. Rosier-Lees (5) , G. Rowell , B. Rudak , C. B. Rulten , J. Ruppel , V. Sahakian , D. A. Sanchez , A. Santangelo , R. Schlickeiser , F. M. Schöck , A. Schulz , U. Schwanke , S. Schwarzburg , S. Schwemmer , F. Sheidaei (3) , J. L. Skilton , H. Sol , G. Spengler , Ł. Stawarz , R. Steenkamp , C. Stegmann , F. Stinzing , K. Stycz , I. Sushch , A. Szostek , J. -P. Tavernet , R. Terrier (3) , M. Tluczykont , K. Valerius , C. van Eldik , George Vasileiadis (1) , C. Venter , A. Viana , P. Vincent , H. J. Völk , F. Volpe , S. Vorobiov (1) , M. Vorster , S. J. Wagner , M. Ward , R. White , A. Wierzcholska , M. Zacharias , A. Zajczyk , A. A. Zdziarski , A. Zech , H. -S. Zechlin

1 LUPM - Laboratoire Univers et Particules de Montpellier
2 LLR - Laboratoire Leprince-Ringuet
3 APC (UMR_7164) - AstroParticule et Cosmologie
4 APC - AHE - APC - Astrophysique des Hautes Energies
5 LAPP - Laboratoire d'Annecy de Physique des Particules
6 GLAST

The observational coverage with HESS of the Carina region in VHE gamma-rays benefits from deep exposure (40 h) of the neighboring open cluster Westerlund 2. The observations have revealed a new extended region of VHE gamma-ray emission. The new VHE source HESS J1018-589 shows a bright, point-like emission region positionally coincident with SNR G284.3-1.8 and 1FGL J1018.6 - 5856 and a diffuse extension towards the direction of PSR J1016-5857. A soft Gamma=2.7+-0.5 photon index, with a differential flux at 1TeV of N0=(4.2+-1.1)10^-13 TeV^-1 cm^-2 s^-1 is found for the point-like source, whereas the total emission region including the diffuse emission region is well fit by a power-law function with spectral index Gamma=2.9+-0.4 and differential flux at 1TeV of N0=(6.8+-1.6) 10^-13 TeV^-1 cm^-2 s^-1. This H.E.S.S. detection motivated follow-up X-ray observations with the XMM-Newton satellite to investigate the origin of the VHE emission. The analysis of the XMM-Newton data resulted in the discovery of a bright, non-thermal point-like source (XMMU J101855.4-58564) with a photon index of Gamma=1.65+-0.08 in the center of SNRG284.3-1.8, and a thermal, extended emission region coincident with its bright northern filament. The characteristics of this thermal emission are used to estimate the plasma density in the region as n~0.5 cm^-3(2.9kpc/d)^2. The position of XMMUJ101855.4-58564 is compatible with the position reported by the Fermi-LAT collaboration for the binary system 1FGL J1018.6-5856 and the variable Swift XRT source identified with it. The new X-ray data are used alongside archival multi-wavelength data to investigate the relationship between the VHE gamma-ray emission from HESSJ1018-589 and the various potential counterparts in the Carina arm region.

Domaines: Phénomènes cosmiques de haute energie [astro-ph.HE]; Phénomènes cosmiques de haute energie [astro-ph.HE]

A. Abramowski, Fabio Acero, F. Aharonian, A. G. Akhperjanian, G. Anton, et al.. Discovery of VHE emission towards the Carina arm region with the H.E.S.S. telescope array: HESS J1018-589. Astronomy and Astrophysics - A&A, 2012, 541, pp.A5. ⟨10.1051/0004-6361/201218843⟩. ⟨in2p3-00684777⟩