2011A&A...525A..46A

Query : 2011A&A...525A..46A

2011A&A...525A..46A - Astronomy and Astrophysics, volume 525A46-46 (2011/1-1)

Revisiting the Westerlund 2 field with the HESS telescope array.

ABRAMOWSKI A., ACERO F., AHARONIAN F., AKHPERJANIAN A.G., ANTON G., BARNACKA A., BARRES DE ALMEIDA U., BAZER-BACHI A.R., BECHERINI Y., BECKER J., BEHERA B., BERNLOEHR K., BOCHOW A., BOISSON C., BOLMONT J., BORDAS P., BORREL V., BRUCKER J., BRUN F., BRUN P., BULIK T., BUESCHING I., BOUTELIER T., CASANOVA S., CERRUTI M., CHADWICK P.M., CHARBONNIER A., CHAVES R.C.G., CHEESEBROUGH A., CONRAD J., CHOUNET L.-M., CLAPSON A.C., COIGNET G., 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., DYKS J., DYRDA M., EGBERTS K., EGER P., ESPIGAT P., FALLON L., FARNIER C., FEGAN S., FEINSTEIN F., FERNANDES M.V., FIASSON A., FOERSTER A., FONTAINE G., FUESSLING M., GABICI S., GALLANT Y.A., GERARD L., GERBIG D., GIEBELS B., GLICENSTEIN J.F., GLUECK B., GORET P., GOERING D., HAGUE J.D., HAMPF D., HAUSER M., HEINZ S., HEINZELMANN G., HENRI G., HERMANN G., HINTON J.A., HOFFMANN A., HOFMANN W., HOFVERBERG P., HOLLERAN M., HOPPE S., HORNS D., JACHOLKOWSKA A., DE JAGER O.C., JAHN C., JUNG I., KATARZYNSKI K., KATZ U., KAUFMANN S., KERSCHHAGGL M., KHANGULYAN D., KHELIFI B., KEOGH D., KLOCHKOV D., KLUZNIAK W., KNEISKE T., KOMIN N., KOSACK K., KOSSAKOWSKI R., LAMANNA G., LENAIN J.-P., LENNARZ D., LOHSE T., LU C.-C., MARANDON V., MARCOWITH A., MASBOU J., MAURIN D., McCOMB T.J.L., MEDINA M.C., MEHAULT J., MODERSKI R., MOULIN E., NAUMANN-GODO M., DE NAUROIS M., NEDBAL D., NEKRASSOV D., NGUYEN N., NICHOLAS B., NIEMIEC J., NOLAN S.J., OHM S., OLIVE J.-F., DE ONA WILHELMI E., OPITZ B., ORFORD K.J., OSTROWSKI M., 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., RYDE F., SAHAKIAN V., SANTANGELO A., SCHLICKEISER R., SCHOECK F.M., SCHOENWALD A., SCHWANKE U., SCHWARZBURG S., SCHWEMMER S., SHALCHI A., SUSHCH I., SIKORA M., SKILTON J.L., SOL H., SPENGLER G., STAWARZ L., STEENKAMP R., STEGMANN C., STINZING F., SZOSTEK A., TAM P.H., TAVERNET J.-P., TERRIER R., TIBOLLA O., TLUCZYKONT M., VALERIUS K., VAN ELDIK C., VASILEIADIS G., VENTER C., VIALLE J.P., VIANA A., VINCENT P., VIVIER M., VOELK H.J., VOLPE F., VOROBIOV S., WAGNER S.J., WARD M., ZDZIARSKI A.A., ZECH A., ZECHLIN H.-S., FUKUI Y., FURUKAWA N., OHAMA A., SANO H., DAWSON J., KAWAMURA A. (The HESS Collaboration)

Abstract (from CDS):

Previous observations with the HESS telescope array revealed the existence of extended very-high-energy (VHE; E>100GeV) γ-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 γ-ray source. The Carina region towards the open cluster Westerlund 2 has been re-observed, increasing the total exposure to 45.9h. The combined dataset includes 33 h of new data and now permits a search for energy-dependent morphology and detailed spectroscopy. A new, hard spectrum VHE γ-ray source, HESSJ1026-582, was discovered with a statistical significance of 7σ. It is positionally coincident with the Fermi LAT pulsar PSRJ1028-5819. The positional coincidence and radio/γ-ray characteristics of the LAT pulsar favors a scenario where the TeV emission originates from a pulsar wind nebula. The nature of HESSJ1023-575 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 HESSJ1023-575 is not yet possible, and contribution from the nearby high-energy pulsar and/or the open cluster remains a possibility.

Abstract Copyright: ∼

Journal keyword(s): gamma rays: stars - HII regions

Simbad objects: 16

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Number of rows : 16
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 M 1 SNR 05 34 31.8 +22 01 03           ~ 6516 1
2 V* CM Tau Psr 05 34 31.9474694616 +22 00 52.153698024           ~ 5476 0
3 NAME Car Arm PoG 10 00 -60.0           ~ 471 1
4 SNR G284.3-01.8 SNR 10 18.3 -59 00           ~ 123 2
5 PSR J1023-5746 Psr 10 23 02.84 -57 46 06.9           ~ 70 0
6 FGES J1023.3-5747 gam 10 23 15.18313 -57 46 34.7840           ~ 57 0
7 V* V712 Car EB* 10 23 58.0126366512 -57 45 48.937268268 15.466 15.473 13.5 12.6   O3If*/WN6+O3If*/WN6 176 0
8 Cl Westerlund 2 OpC 10 23 58.1 -57 45 49           ~ 400 0
9 GUM 29 HII 10 24 14.6 -57 46 58           ~ 219 0
10 WR 20b WR* 10 24 18.3978418584 -57 48 29.776921704     13.7 12.0   WN6ha 59 0
11 NGC 3247 OpC 10 25 52 -57 55.6   7.99 7.6     ~ 39 0
12 PSR J1028-5819 Psr 10 28 27.888 -58 19 06.14           ~ 122 1
13 HESS J1718-385 gam 17 18 07 -38 33.0           ~ 32 0
14 PSR B1823-13 Psr 18 26 13.06 -13 34 48.1           ~ 460 1
15 ARGO J1912+1026 gam 19 12 14.9 +10 21 06           ~ 51 0
16 NAME Carina Region reg ~ ~           ~ 192 0

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