2012A&A...537A.114A

Query : 2012A&A...537A.114A

2012A&A...537A.114A - Astronomy and Astrophysics, volume 537A, 114-114 (2012/1-1)

Discovery of extended VHE γ-ray emission from the vicinity of the young massive stellar cluster Westerlund 1.

ABRAMOWSKI A., ACERO F., AHARONIAN F., AKHPERJANIAN A.G., ANTON G., BALZER A., BARNACKA A., BARRES DE ALMEIDA U., BECHERINI Y., BECKER J., BEHERA B., BERNLOEHR K., BIRSIN E., BITEAU J., BOCHOW A., BOISSON C., BOLMONT J., BORDAS P., BRUCKER J., BRUN F., BRUN P., BULIK T., BUESCHING I., CARRIGAN S., CASANOVA S., CERRUTI M., CHADWICK P.M., CHARBONNIER A., CHAVES R.C.G., CHEESEBROUGH A., CHOUNET L.-M., CLAPSON A.C., COIGNET G., COLOGNA G., CONRAD J., DALTON M., DANIEL M.K., DAVIDS I.D., DEGRANGE B., DEIL C., DICKINSON H.J., DJANNATI-ATAIE A., DOMAINKO W., DRURY L.O'C., DUBOIS F., DUBUS G., DUTSON K., DYKS J., DYRDA M., EGBERTS K., EGER P., ESPIGAT P., FALLON L., FARNIER C., FEGAN S., FEINSTEIN F., FERNANDES M.V., FIASSON A., FONTAINE G., FOERSTER A., FUESSLING M., GALLANT Y.A., GAST H., GERARD L., GERBIG D., GIEBELS B., GLICENSTEIN J.F., GLUECK B., GORET P., GOERING D., HAEFFNER S., HAGUE J.D., HAMPF D., HAUSER M., HEINZ S., HEINZELMANN G., HENRI G., HERMANN G., HINTON J.A., HOFFMANN A., HOFMANN W., HOFVERBERG P., HOLLER M., HORNS D., JACHOLKOWSKA A., DE JAGER O.C., JAHN C., JAMROZY M., JUNG I., KASTENDIECK M.A., KATARZYNSKI K., KATZ U., KAUFMANN S., KEOGH D., KHANGULYAN D., KHELIFI B., KLOCHKOV D., KLUZNIAK W., KNEISKE T., KOMIN NU., KOSACK K., KOSSAKOWSKI R., LAFFON H., LAMANNA G., LENNARZ D., LOHSE T., LOPATIN A., LU C.-C., MARANDON V., MARCOWITH A., MASBOU J., MAURIN D., MAXTED N., MAYER M., McCOMB T.J.L., MEDINA M.C., MEHAULT J., MODERSKI R., MOULIN E., NAUMANN C.L., NAUMANN-GODO M., DE NAUROIS M., NEDBAL D., NEKRASSOV D., NGUYEN N., NICHOLAS B., NIEMIEC J., NOLAN S.J., OHM S., DE ONA WILHELMI E., OPITZ B., OSTROWSKI M., OYA I., PANTER M., PAZ ARRIBAS M., PEDALETTI G., PELLETIER G., PETRUCCI P.-O., PITA S., PUEHLHOFER G., PUNCH M., QUIRRENBACH A., RAUE M., RAYNER S.M., REIMER A., REIMER O., RENAUD M., DE LOS REYES R., RIEGER F., RIPKEN J., ROB L., ROSIER-LEES S., ROWELL G., RUDAK B., RULTEN C.B., RUPPEL J., SAHAKIAN V., SANCHEZ D., SANTANGELO A., SCHLICKEISER R., SCHOECK F.M., SCHULZ A., SCHWANKE U., SCHWARZBURG S., SCHWEMMER S., SHEIDAEI F., SIKORA M., SKILTON J.L., SOL H., SPENGLER G., STAWARZ L., STEENKAMP R., STEGMANN C., STINZING F., STYCZ K., SUSHCH I., SZOSTEK A., TAVERNET J.-P., TERRIER R., TLUCZYKONT M., VALERIUS K., VAN ELDIK C., VASILEIADIS G., VENTER C., VIALLE J.P., VIANA A., VINCENT P., VOELK H.J., VOLPE F., VOROBIOV S., VORSTER M., WAGNER S.J., WARD M., WHITE R., WIERZCHOLSKA A., ZACHARIAS M., ZAJCZYK A., ZDZIARSKI A.A., ZECH A. and ZECHLIN H.-S.

Abstract (from CDS):

Result. obtained in very-high-energy (VHE; E≥100GeV) γ-ray observations performed with the H.E.S.S. telescope array are used to investigate particle acceleration processes in the vicinity of the young massive stellar cluster Westerlund 1 (Wd 1). Imaging of Cherenkov light from γ-ray induced particle cascades in the Earth's atmosphere is used to search for VHE γ rays from the region around Wd1. Possible catalogued counterparts are searched for and discussed in terms of morphology and energetics of the H.E.S.S. source. The detection of the degree-scale extended VHE γ-ray source HESS J1646-458 is reported based on 45h of H.E.S.S. observations performed between 2004 and 2008. The VHE γ-ray source is centred on the nominal position of Wd 1 and detected with a total statistical significance of ∼20σ. The emission region clearly extends beyond the H.E.S.S. point-spread function (PSF). The differential energy spectrum follows a power law in energy with an index of Γ=2.19±0.08stat±0.20sys and a flux normalisation at 1TeV of Φ0=(9.0±1.4stat±1.8sys)x10–12/TeV/cm2/s. The integral flux above 0.2TeV amounts to (5.2±0.9)x10–11/cm2/s. Four objects coincident with HESS J1646-458 are discussed in the search of a counterpart, namely the magnetar CXOU J164710.2-455216, the X-ray binary 4U 1642-45, the pulsar PSR J1648-4611 and the massive stellar cluster Wd 1. In a single-source scenario, Wd 1 is favoured as site of VHE particle acceleration. Here, a hadronic parent population would be accelerated within the stellar cluster. Beside this, there is evidence for a multi-source origin, where a scenario involving PSR J1648-4611 could be viable to explain parts of the VHE γ-ray emission of HESS J1646-458.

Abstract Copyright: ∼

Journal keyword(s): open clusters and associations: general - gamma rays: stars - astroparticle physics

Simbad objects: 33

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Number of rows : 33
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 17418 0
2 LHA 120-N 51D HII 05 25 17.3 -67 22 47           ~ 114 0
3 M 1 SNR 05 34 30.9 +22 00 53           ~ 6186 1
4 NAME 30 Dor C Superbubble Rad 05 35 50.8 -69 12 22           ~ 47 1
5 HD 259440 HXB 06 32 59.2566076656 +05 48 01.160755848 9.17 9.63 9.15     B0pe 219 0
6 NAME Vela X Psr 08 33 08.880 -45 11 24.36           ~ 281 1
7 NAME Vela Jr SN BL? 08 52.0 -46 20           ~ 474 2
8 RCW 38 SFR 08 59 05.50 -47 30 39.4           ~ 305 2
9 Cl Westerlund 2 OpC 10 23 58.1 -57 45 49           ~ 356 0
10 ESO 134-11 HII 14 40 29 -62 38.7           ~ 564 1
11 NAME Lupus SN SNR 15 02 22.1 -42 05 49           ~ 1327 1
12 HESS J1634-472 gam 16 34 51.11927 -47 14 01.9360           ~ 28 0
13 SNR G337.8-00.1 SNR 16 39.0 -46 59           ~ 76 0
14 AX J1640.7-4632 BL? 16 40 43.2 -46 31 48           ~ 158 2
15 SNR G338.5+00.1 SNR 16 41 09 -46 19.0           ~ 44 0
16 [R2003] 447 ? 16 45.6 -44 46           ~ 3 0
17 4U 1642-45 LXB 16 45 47.7 -45 36 40     14.30     ~ 416 1
18 HESS J1646-458 gam 16 46 00.0 -45 48 00           ~ 12 0
19 SNR G340.4+00.4 SNR 16 46.5 -44 39           ~ 37 0
20 Cl Westerlund 1 Cl* 16 47 02.4 -45 51 07           ~ 565 0
21 PSR J1647-4552 Psr 16 47 10.18 -45 52 16.7           ~ 198 1
22 SNR G340.6+00.3 SNR 16 47.7 -44 34           ~ 36 0
23 PSR J1648-4611 Psr 16 48 22.02 -46 11 16.0           ~ 65 0
24 2FGL J1650.6-4603 gam 16 50 36.0 -46 03 00           ~ 4 0
25 2FGL J1651.8-4439 gam 16 52 20.89 -44 28 00.8           ~ 2 0
26 2FGL J1653.9-4627 gam 16 53 54.0 -46 27 00           ~ 2 0
27 1FGL J1711.7-3944c BL? 17 12 27 -39 41.2     12.27     ~ 722 1
28 SNR G353.6-00.7 SNR 17 31 55.0 -34 42 36           ~ 142 0
29 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 14385 0
30 NAME Arches Cluster Cl* 17 45 50.5 -28 49 28           ~ 735 0
31 PSR B1823-13 Psr 18 26 13.06 -13 34 48.1           ~ 419 1
32 V* V479 Sct HXB 18 26 15.0561548880 -14 50 54.247274304 12.02 12.23 11.27 11.04   ON6V((f))z 570 2
33 3C 461 BL? 23 23 24.000 +58 48 54.00     14.30     ~ 2789 1

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