Probing the extent of the non-thermal emission from the Vela X region at TeV energies with HESS

被引:62
作者
Abramowski, A. [1 ]
Acero, F. [2 ]
Aharonian, F. [3 ,4 ,5 ]
Akhperjanian, A. G. [5 ,6 ]
Anton, G. [7 ]
Balenderan, S. [8 ]
Balzer, A. [7 ]
Barnacka, A. [9 ,10 ]
Becherini, Y. [11 ,12 ]
Tjus, J. Becker [13 ]
Bernloehr, K. [3 ,14 ]
Birsin, E. [14 ]
Biteau, J. [12 ]
Bochow, A. [3 ]
Boisson, C. [15 ]
Bolmont, J. [16 ]
Bordas, P. [17 ]
Brucker, J. [7 ]
Brun, F. [12 ]
Brun, P. [10 ]
Bulik, T. [18 ]
Carrigan, S. [3 ]
Casanova, S. [3 ,19 ]
Cerruti, M. [15 ]
Chadwick, P. M. [8 ]
Charbonnier, A. [16 ]
Chaves, R. C. G. [3 ,10 ]
Cheesebrough, A. [8 ]
Cologna, G. [20 ]
Conrad, J. [21 ]
Couturier, C. [16 ]
Dalton, M. [14 ,22 ]
Daniel, M. K. [8 ]
Davids, I. D. [23 ]
Degrange, B. [12 ]
Deil, C. [3 ]
deWilt, P. [24 ]
Dickinson, H. J. [21 ]
Djannati-Atai, A. [11 ]
Domainko, W. [3 ]
Drury, L. O' C. [4 ]
Dubois, F. [29 ]
Dubus, G. [25 ]
Dutson, K. [26 ]
Dyks, J. [9 ]
Dyrda, M. [27 ]
Egberts, K. [28 ]
Eger, P. [7 ]
Espigat, P. [11 ]
Fallon, L. [4 ]
机构
[1] Univ Hamburg, Inst Expt Phys, D-22761 Hamburg, Germany
[2] Univ Montpellier 2, Lab Universe & Particules Montpellier, CNRS, IN2P3, F-34095 Montpellier 5, France
[3] Max Planck Inst Kernphys, D-69029 Heidelberg, Germany
[4] Dublin Inst Adv Studies, Dublin 2, Ireland
[5] Natl Acad Sci Republ Armenia, Yerevan, Armenia
[6] Yerevan Phys Inst, Yerevan 375036, Armenia
[7] Univ Erlangen Nurnberg, Inst Phys, D-91058 Erlangen, Germany
[8] Univ Durham, Dept Phys, Durham DH1 3LE, England
[9] Nicolaus Copernicus Astron Ctr, PL-00716 Warsaw, Poland
[10] CEA Saclay, DSM Irfu, F-91191 Gif Sur Yvette, France
[11] Univ Paris Diderot, APC, CNRS, IN2P3,CEA Irfu,Observ Paris, F-75205 Paris 13, France
[12] Ecole Polytech, Lab Leprince Ringuet, CNRS, IN2P3, F-91128 Palaiseau, France
[13] Ruhr Univ Bochum, Inst Theoret Phys, Lehrstuhl Weltraum & Astrophys 4, D-44780 Bochum, Germany
[14] Univ Berlin, Inst Phys, D-12489 Berlin, Germany
[15] Univ Paris Diderot, CNRS, Observ Paris, LUTH, F-92190 Meudon, France
[16] Univ Paris 07, Univ Paris 06, LPNHE, CNRS,IN2P3, F-75252 Paris 5, France
[17] Univ Tubingen, Inst Astron & Astrophys, D-72076 Tubingen, Germany
[18] Univ Warsaw, Astron Observ, PL-00478 Warsaw, Poland
[19] North West Univ, Unit Space Phys, ZA-2520 Potchefstroom, South Africa
[20] Heidelberg Univ, Landessternwarte, D-69117 Heidelberg, Germany
[21] Stockholm Univ, Dept Phys, Oskar Klein Ctr, Albanova Univ Ctr, S-10691 Stockholm, Sweden
[22] Univ Bordeaux 1, CNRS, IN2P3, Ctr Etud Nucl Bordeaux Gradignan, F-33175 Gradignan, France
[23] Univ Namibia, Dept Phys, Windhoek, Namibia
[24] Univ Adelaide, Sch Chem & Phys, Adelaide, SA 5005, Australia
[25] UJF Grenoble 1, CNRS, INSU, IPAG,UMR 5274, F-38041 Grenoble, France
[26] Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England
[27] Inst Fizyki Jadrowej PAN, PL-31342 Krakow, Poland
[28] Univ Innsbruck, Inst Astro & Teilchenphys, A-6020 Innsbruck, Austria
[29] Univ Savoie, Lab Annecy le Vieux Phys Particules, CNRS, IN2P3, F-74941 Annecy Le Vieux, France
[30] Uniwersytet Jagiellonski, Obserwatorium Astron, PL-30244 Krakow, Poland
[31] Nicolaus Copernicus Univ, Torun Ctr Astron, PL-87100 Torun, Poland
[32] Charles Univ Prague, Fac Math & Phys, Inst Particle & Nucl Phys, CR-18000 Prague 8, Czech Republic
[33] Univ Leeds, Sch Phys & Astron, Leeds LS2 9JT, W Yorkshire, England
关键词
radiation mechanisms: non-thermal; ISM: individual objects: Vela X; ISM: individual objects: HESS J0835-455; gamma rays: general; PULSAR WIND NEBULA; ATMOSPHERIC CHERENKOV TELESCOPES; RAY-EMISSION; CRAB-NEBULA; GAMMA-RAYS; RADIO; EVOLUTION; SYSTEM; DISCOVERY; JET;
D O I
10.1051/0004-6361/201219919
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Context. Vela X is a region of extended radio emission in the western part of the Vela constellation: one of the nearest pulsar wind nebulae, and associated with the energetic Vela pulsar (PSR B0833-45). Extended very-high-energy (VHE) gamma-ray emission (HESS J0835-455) was discovered using the H. E. S. S. experiment in 2004. The VHE gamma-ray emission was found to be coincident with a region of X-ray emission discovered with ROSAT above 1.5 keV (the so-called Vela X cocoon): a filamentary structure extending southwest from the pulsar to the centre of Vela X. Aims. A deeper observation of the entire Vela X nebula region, also including larger offsets from the cocoon, has been performed with H. E. S. S. This re-observation was carried out in order to probe the extent of the non-thermal emission from the Vela X region at TeV energies and to investigate its spectral properties. Methods. To increase the sensitivity to the faint gamma-ray emission from the very extended Vela X region, a multivariate analysis method combining three complementary reconstruction techniques of Cherenkov-shower images is applied for the selection of gamma-ray events. The analysis is performed with the On/Off background method, which estimates the background from separate observations pointing away from Vela X; towards regions free of gamma-ray sources but with comparable observation conditions. Results. The gamma-ray surface brightness over the large Vela X region reveals that the detection of non-thermal VHE gamma-ray emission from the PWN HESS J0835-455 is statistically significant over a region of radius 1.2 degrees around the position alpha = 08(h)35(m)00(s), delta = -45 degrees 36'00 '' (J2000). The Vela X region exhibits almost uniform gamma-ray spectra over its full extent: the differential energy spectrum can be described by a power-law function with a hard spectral index Gamma = 1.32 +/- 0.06(stat) +/- 0.12(sys) and an exponential cutoff at an energy of (14.0 +/- 1.6(stat) +/- 2.6(sys)) TeV. Compared to the previous H. E. S. S. observations of Vela X the new analysis confirms the general spatial overlap of the bulk of the VHE gamma-ray emission with the X-ray cocoon, while its extent and morphology appear more consistent with the (more extended) radio emission, contradicting the simple correspondence between VHE gamma-ray and X-ray emissions. Morphological and spectral results challenge the interpretation of the origin of gamma-ray emission in the GeV and TeV ranges in the framework of current models.
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页数:11
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