Discovery of the two wings of the Kookaburra complex in VHE gamma -rays with H.E.S.S

F. Aharonian , A. G. Akhperjanian , A. R. Bazer-Bachi (1) , M. Beilicke , W. Benbow , D. Berge , K. Bernlöhr , C. Boisson (2) , O. Bolz , V. Borrel (1) , I. Braun , F. Breitling , A. M. Brown , R. Bühler , I. Büsching , S. Carrigan , P. M. Chadwick , L.-M. Chounet (3) , R. Cornils , L. Costamante , B. Degrange (3) , H. J. Dickinson , A. Djannati-Ataï (4) , L. O'C. Drury , G. Dubus (3) , K. Egberts , D. Emmanoulopoulos , P. Espigat (4) , F. Feinstein (5) , E. Ferrero , G. Fontaine (3) , Seb. Funk , S. Funk , Y.A. Gallant (5) , B. Giebels (3) , J. F. Glicenstein (6) , P. Goret (6) , C. Hadjichristidis , D. Hauser , M. Hauser , G. Heinzelmann , G. Henri (7) , G. Hermann , J. A. Hinton , W. Hofmann , M. Holleran , D. Horns , A. Jacholkowska (5) , O. C. de Jager , B. Khélifi (3) , Nu. Komin , A. Konopelko , I. J. Latham , R. Le Gallou , A. Lemière (4) , M. Lemoine-Goumard (3) , T. Lohse , J. M. Martin , O. Martineau-Huynh , A. Marcowith (1) , C. Masterson , T. J. L. Mccomb , M. de Naurois , D. Nedbal , S. J. Nolan , A. Noutsos , K. J. Orford , J. L. Osborne , M. Ouchrif , M. Panter , G. Pelletier (7) , S. Pita (4) , G. Pühlhofer , M. Punch (4) , B. C. Raubenheimer , M. Raue , S. M. Rayner , A. Reimer , O. Reimer , J. Ripken , L. Rob , L. Rolland , G. Rowell , V. Sahakian , L. Saugé (7) , S. Schlenker , R. Schlickeiser , U. Schwanke , H. Sol (2) , D. Spangler , F. Spanier , R. Steenkamp , C. Stegmann , G. Superina (3) , J.-P. Tavernet , R. Terrier (8) , C.G. Théoret (4) , M. Tluczykont (3) , C. van Eldik , G. Vasileiadis (5) , C. Venter , P. Vincent , H. J. Völk , S. J. Wagner , M. Ward

1 CESR - Centre d'étude spatiale des rayonnements
2 LUTH (UMR_8102) - Laboratoire Univers et Théories
3 LLR - Laboratoire Leprince-Ringuet
4 APC (UMR_7164) - AstroParticule et Cosmologie
5 LPTA - Laboratoire de Physique Théorique et Astroparticules
6 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
7 LAOG - Laboratoire d'Astrophysique de Grenoble
8 APC - AHE - APC - Astrophysique des Hautes Energies

Aims. Search for Very High Energy gamma-ray emission in the Kookaburra complex through observations with the H.E.S.S. array. Methods. Stereoscopic imaging of Cherenkov light emission of the gamma-ray showers in the atmosphere is used for the reconstruction and selection of the events to search for gamma-ray signals. Their spectrum is derived by a forward-folding maximum likelihood fit. Results. Two extended gamma-ray sources with an angular (68%) radius of 3.3-3.4' are discovered at high (>13sigma) statistical significance: HESS J1420-607 and HESS J1418-609. They exhibit a flux above 1 TeV of (2.97+/-0.18stat +/-0.60sys)x10-12 and (2.17+/-0.17stat +/-0.43sys)x10-12 cm-2 s-1, respectively, and similar hard photon indices ~2.2. Multi-wavelength comparisons show spatial coincidence with the wings of the Kookaburra. Two pulsar wind nebulae candidates, K3/PSR J1420-6048 and the Rabbit, lie on the edge of the H.E.S.S. sources. Conclusions. The two new sources confirm the non-thermal nature of at least parts of the two radio wings which overlap with the gamma-ray emission and establish their connection with the two X-ray pulsar wind nebulae candidates. Given the large point spread function of EGRET, the unidentified source(s) 3EG J1420-6038/GeV J1417-6100 could possibly be related to either or both H.E.S.S. sources. The most likely explanation for the Very High Energy gamma-rays discovered by H.E.S.S. is inverse Compton emission of accelerated electrons on the Cosmic Microwave Background near the two candidate pulsar wind nebulae, K3/PSR J1420-6048 and the Rabbit. Two scenarios which could lead to the observed large (~10 pc) offset-nebula type morphologies are briefly discussed.

Mots clés: ISM: general; gamma rays: observations; radiation mechanisms: non-thermal

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, A. R. Bazer-Bachi, M. Beilicke, W. Benbow, et al.. Discovery of the two wings of the Kookaburra complex in VHE gamma -rays with H.E.S.S. Astronomy and Astrophysics - A&A, 2006, 456, pp.245-251. ⟨10.1051/0004-6361:20065511⟩. ⟨in2p3-00124916⟩