Revisiting the Westerlund 2 field with the HESS telescope array

被引:50
作者
Abramowski, A. [1 ]
Acero, F. [15 ]
Aharonian, F. [2 ,13 ,34 ]
Akhperjanian, A. G. [3 ,34 ]
Anton, G. [16 ]
Barnacka, A. [7 ,24 ]
de Almeida, U. Barres [8 ]
Bazer-Bachi, A. R. [4 ]
Becherini, Y. [12 ]
Becker, J. [21 ]
Behera, B. [14 ]
Bernloehr, K. [2 ,5 ]
Bochow, A. [2 ]
Boisson, C. [6 ]
Bolmont, J. [19 ]
Bordas, P. [18 ]
Borrel, V. [4 ]
Brucker, J. [16 ]
Brun, F. [19 ]
Brun, P. [7 ]
Bulik, T. [29 ]
Buesching, I. [9 ]
Boutelier, T. [17 ]
Casanova, S. [2 ]
Cerruti, M. [6 ]
Chadwick, P. M. [8 ]
Charbonnier, A. [19 ]
Chaves, R. C. G. [2 ]
Cheesebrough, A. [8 ]
Conrad, J. [31 ]
Chounet, L. -M. [10 ]
Clapson, A. C. [2 ]
Coignet, G. [11 ]
Dalton, M. [5 ]
Daniel, M. K. [8 ]
Davids, I. D. [9 ,22 ]
Degrange, B. [10 ]
Deil, C. [11 ]
Dickinson, H. J. [8 ]
Djannati-Atai, A. [12 ]
Domainko, W. [2 ]
Drury, L. O'C. [13 ]
Dubois, F. [11 ]
Dubus, G. [17 ]
Dyks, J. [24 ]
Dyrda, M. [28 ]
Egberts, K. [2 ,30 ]
Eger, P. [16 ]
Espigat, P. [12 ]
Fallon, L. [13 ]
机构
[1] Univ Hamburg, Inst Expt Phys, D-22761 Hamburg, Germany
[2] Max Planck Inst Kernphys, D-69029 Heidelberg, Germany
[3] Yerevan Phys Inst, Yerevan 375036, Armenia
[4] UPS, CNRS, Ctr Etud Spatiale Rayonnements, F-31029 Toulouse 4, France
[5] Humboldt Univ, Inst Phys, D-12489 Berlin, Germany
[6] Univ Paris Diderot, LUTH, Observ Paris, CNRS, F-92190 Meudon, France
[7] CEA Saclay, DSM, IRFU, F-91191 Gif Sur Yvette, France
[8] Univ Durham, Dept Phys, Durham DH1 3LE, England
[9] North West Univ, Unit Space Phys, ZA-2520 Potchefstroom, South Africa
[10] Ecole Polytech, Lab Leprince Ringuet, CNRS, IN2P3, F-91128 Palaiseau, France
[11] Univ Savoie, Lab Annecy le Vieux Phys Particules, CNRS, IN2P3, F-74941 Annecy Le Vieux, France
[12] Univ Paris 07, CNRS, CEA, Observ Paris,UMR 7164, F-75205 Paris 13, France
[13] Dublin Inst Adv Studies, Dublin 2, Ireland
[14] Univ Heidelberg, Landessternwarte, D-69117 Heidelberg, Germany
[15] Univ Montpellier 2, Lab Phys Theor & Astroparticules, CNRS, IN2P3,CC 70, F-34095 Montpellier 5, France
[16] Univ Erlangen Nurnberg, Inst Phys, D-91058 Erlangen, Germany
[17] Univ Grenoble 1, Lab Astrophys Grenoble, INSU, CNRS, F-38041 Grenoble 9, France
[18] Univ Tubingen, Inst Astron & Astrophys, D-72076 Tubingen, Germany
[19] Univ Paris 07, LPNHE, Univ Paris 06, CNRS,IN2P3, F-75252 Paris 5, France
[20] Charles Univ Prague, Fac Math & Phys, Inst Particle & Nucl Phys, CR-18000 Prague 8, Czech Republic
[21] Ruhr Univ Bochum, Inst Theoret Phys, Lehrstuhl Weltraum & Astrophys 4, D-44780 Bochum, Germany
[22] Univ Namibia, Dept Phys, Windhoek, Namibia
[23] Uniwersytet Jagiellonski, Obserwatorium Astron, PL-30244 Krakow, Poland
[24] Nicolaus Copernicus Astron Ctr, PL-00716 Warsaw, Poland
[25] Univ Leeds, Sch Phys & Astron, Leeds LS2 9JT, W Yorkshire, England
[26] Univ Adelaide, Sch Chem & Phys, Adelaide, SA 5005, Australia
[27] Nicholas Copernicus Univ, Torun Ctr Astron, PL-87100 Torun, Poland
[28] Inst Fizyki Jadrowej PAN, PL-31342 Krakow, Poland
[29] Univ Warsaw, Astron Observ, PL-00478 Warsaw, Poland
[30] Leopold Franzens Univ Innsbruck, Inst Astro & Teilchenphys, A-6020 Innsbruck, Austria
[31] Stockholm Univ, Oskar Klein Ctr, Dept Phys, Albanova Univ Ctr, S-10691 Stockholm, Sweden
[32] Royal Inst Technol KTH, Oskar Klein Ctr, Dept Phys, S-10691 Stockholm, Sweden
[33] Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England
[34] Natl Acad Sci Republ Armenia, Yerevan, Armenia
[35] Nagoya Univ, Dept Astrophys, Chikusa Ku, Nagoya, Aichi 4648602, Japan
基金
英国科学技术设施理事会; 新加坡国家研究基金会;
关键词
gamma rays: stars; HII regions; GAMMA-RAY EMISSION; PULSAR WIND NEBULAE; LARGE-AREA TELESCOPE; CLUSTER WESTERLUND-2; X-RAY; DISCOVERY; GALAXY; RADIO; EVOLUTION; RADIATION;
D O I
10.1051/0004-6361/201015290
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Aims. Previous observations with the HESS 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, HESS J1026-582, was discovered with a statistical significance of 7 sigma. It is positionally coincident with the Fermi LAT pulsar PSRJ1028-5819. 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 HESS 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.
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