Revisiting the Westerlund 2 Field with the H.E.S.S. Telescope Array
Abstract
Aims. Previous observations with the H.E.S.S. telescope array revealed the existence of extended very-high-energy (VHE; E>100 GeV) {\gamma}-ray emission, HESS J1023-575, coincident with the young stellar cluster Westerlund 2. At the time of discovery, the origin of the observed emission was not unambiguously identified, and follow-up observations have been performed to further investigate the nature of this {\gamma}-ray source. Methods. The Carina region towards the open cluster Westerlund 2 has been re-observed, increasing the total exposure to 45.9 h. The combined dataset includes 33 h of new data and now permits a search for energy-dependent morphology and detailed spectroscopy. Results. A new, hard spectrum VHE {\gamma}-ray source, HESSJ1026-582, was discovered with a statistical significance of 7{\sigma}. It is positionally coincident with the Fermi LAT pulsar PSR J1028-5819. The positional coincidence and radio/{\gamma}-ray characteristics of the LAT pulsar favors a scenario where the TeV emission originates from a pulsar wind nebula. The nature of HESS J1023-575 is discussed in light of the deep H.E.S.S. observations and recent multi-wavelength discoveries, including the Fermi LAT pulsar PSRJ1022-5746 and giant molecular clouds in the region. Despite the improved VHE dataset, a clear identification of the object responsible for the VHE emission from HESS J1023-575 is not yet possible, and contribution from the nearby high-energy pulsar and/or the open cluster remains a possibility.
Cite
@article{arxiv.1009.3012,
title = {Revisiting the Westerlund 2 Field with the H.E.S.S. Telescope Array},
author = {The HESS Collaboration and A. Abramowski and F. Acero and F. Aharonian and A. G. Akhperjanian and G. Anton and A. Barnacka and U. Barres de Almeida and A. R. Bazer-Bachi and Y. Becherini and J. Becker and B. Behera and K. Bernlöhr and A. Bochow and C. Boisson and J. Bolmont and P. Bordas and V. Borrel and J. Brucker and F. Brun and P. Brun and T. Bulik and I. Büsching and T. Boutelier and S. Casanova and M. Cerruti and P. M. Chadwick and A. Charbonnier and R. C. G. Chaves and A. Cheesebrough and J. Conrad and L. -M. Chounet and A. C. Clapson and G. Coignet and M. Dalton and M. K. Daniel and I. D. Davids and B. Degrange and C. Deil and H. J. Dickinson and A. Djannati-Ataï and W. Domainko and L. O'C. Drury and F. Dubois and G. Dubus and J. Dyks and M. Dyrda and K. Egberts and P. Eger and P. Espigat and L. Fallon and C. Farnier and S. Fegan and F. Feinstein and M. V. Fernandes and A. Fiasson and A. Förster and G. Fontaine and M. Füßling and S. Gabici and Y. A. Gallant and L. Gérard and D. Gerbig and B. Giebels and J. F. Glicenstein and B. Glück and P. Goret and D. Göring and J. D. Hague and D. Hampf and M. Hauser and S. Heinz and G. Heinzelmann and G. Henri and G. Hermann and J. A. Hinton and A. Hoffmann and W. Hofmann and P. Hofverberg and M. Holleran and S. Hoppe and D. Horns and A. Jacholkowska and O. C. de Jager and C. Jahn and I. Jung and K. Katarzyński and U. Katz and S. Kaufmann and M. Kerschhaggl and D. Khangulyan and B. Khélifi and D. Keogh and D. Klochkov and W. Kluźniak24 and T. Kneiske and Nu. Komin and K. Kosack and R. Kossakowski and G. Lamanna and J. -P. Lenain and D. Lennarz and T. Lohse and C. -C. Lu and V. Marandon and A. Marcowith and J. Masbou and D. Maurin and T. J. L. McComb and M. C. Medina and J. Méhault and R. Moderski and E. Moulin and M. Naumann-Godo and M. de Naurois and D. Nedbal and D. Nekrassov and N. Nguyen and B. Nicholas and J. Niemiec and S. J. Nolan and S. Ohm and J-F. Olive and E. de Oña Wilhelmi and B. Opitz and K. J. Orford and M. Ostrowski and M. Panter and M. Paz Arribas and G. Pedaletti1 and G. Pelletier and P. -O. Petrucci and S. Pita1 and G. Pühlhofer and M. Punch and A. Quirrenbach and M. Raue and S. M. Rayner and A. Reimer and O. Reimer and M. Renaud and R. de los Reyes and F. Rieger1 and J. Ripken and L. Rob and S. Rosier-Lees and G. Rowell and B. Rudak and C. B. Rulten and J. Ruppel and F. Ryde and V. Sahakian and A. Santangelo and R. Schlickeiser and F. M. Schöck and A. Schönwald and U. Schwanke and S. Schwarzburg and S. Schwemmer and A. Shalchi and I. Sushch and M. Sikora and J. L. Skilton and H. Sol and G. Spengler and Ł. Stawarz and R. Steenkamp and C. Stegmann and F. Stinzing and A. Szostek and P. H. Tam and J. -P. Tavernet and R. Terrier and O. Tibolla and M. Tluczykont and K. Valerius and C. van Eldik and G. Vasileiadis and C. Venter and J. P. Vialle and A. Viana and P. Vincent and M. Vivier and H. J. Völk and F. Volpe and S. Vorobiov and S. J. Wagner and M. Ward and A. A. Zdziarski and A. Zech and H. -S. Zechlin and Y. Fukui and N. Furukawa and A. Ohama and H. Sano and J. Dawson and A. Kawamura},
journal= {arXiv preprint arXiv:1009.3012},
year = {2015}
}
Comments
Accepted for publication on A&A