2007A&A...475L...9A

Query : 2007A&A...475L...9A

2007A&A...475L...9A - Astronomy and Astrophysics, volume 475L9-13 (2007/11-4)

New constraints on the mid-IR EBL from the HESS discovery of VHE γ-rays from 1ES0229+200.

AHARONIAN F., AKHPERJANIAN A.G., BARRES DE ALMEIDA U., BAZER-BACHI A.R., BEHERA B., BEILICKE M., BENBOW W., BERNLOEHR K., BOISSON C., BOLZ O., BORREL V., BRAUN I., BRION E., BROWN A.M., BUEHLER R., BULIK T., BUESCHING I., BOUTELIER T., CARRIGAN S., CHADWICK P.M., CHOUNET L.-M., CLAPSON A.C., COIGNET G., CORNILS R., COSTAMANTE L., DALTON M., DEGRANGE B., DICKINSON H.J., DJANNATI-ATAIE A., DOMAINKO W., DRURY L.O'C., DUBOIS F., DUBUS G., DYKS J., EGBERTS K., EMMANOULOPOULOS D., ESPIGAT P., FARNIER C., FEINSTEIN F., FIASSON A., FOERSTER A., FONTAINE G., FUNK SEB., FUESSLING M., GALLANT Y.A., GIEBELS B., GLICENSTEIN J.F., GLUECK B., GORET P., HADJICHRISTIDIS C., HAUSER D., HAUSER M., HEINZELMANN G., HENRI G., HERMANN G., HINTON J.A., HOFFMANN A., HOFMANN W., HOLLERAN M., HOPPE S., HORNS D., JACHOLKOWSKA A., DE JAGER O.C., JUNG I., KATARZYNSKI K., KENDZIORRA E., KERSCHHAGGL M., KHELIFI B., KEOGH D., KOMIN N., KOSACK K., LAMANNA G., LATHAM I.J., LEMIERE A., LEMOINE-GOUMARD M., LENAIN J.-P., LOHSE T., MARTIN J.M., MARTINEAU-HUYNH O., MARCOWITH A., MASTERSON C., MAURIN D., MAURIN G., McCOMB T.J.L., MODERSKI R., MOULIN E., DE NAUROIS M., NEDBAL D., NOLAN S.J., OHM S., OLIVE J.-P., DE ONA WILHELMI E., ORFORD K.J., OSBORNE J.L., OSTROWSKI M., PANTER M., PEDALETTI G., PELLETIER G., PETRUCCI P.-O., PITA S., PUEHLHOFER G., PUNCH M., RANCHON S., RAUBENHEIMER B.C., RAUE M., RAYNER S.M., RENAUD M., RIPKEN J., ROB L., ROLLAND L., ROSIER-LEES S., ROWELL G., RUDAK B., RUPPEL J., SAHAKIAN V., SANTANGELO A., SCHLICKEISER R., SCHOECK F., SCHROEDER R., SCHWANKE U., SCHWARZBURG S., SCHWEMMER S., SHALCHI A., SOL H., SPANGLER D., STAWARZ L., STEENKAMP R., STEGMANN C., SUPERINA G., TAM P.H., TAVERNET J.-P., TERRIER R., VAN ELDIK C., VASILEIADIS G., VENTER C., VIALLE J.P., VINCENT P., VIVIER M., VOELK H.J., VOLPE F., WAGNER S.J., WARD M., ZDZIARSKI A.A. and ZECH A.

Abstract (from CDS):

To investigate the very high energy (VHE: >100GeV) γ-ray emission from the high-frequency peaked BL Lac 1ES0229+200. Observations of 1ES0229+200 at energies above 580GeV were performed with the High Energy Stereoscopic System (HESS) in 2005 and 2006. 1ES0229+200 is discovered by HESS to be an emitter of VHE photons. A signal is detected at the 6.6σ level in the HESS observations (41.8h live time). The integral flux above 580GeV is (9.4±1.5stat±1.9syst)x10–13/cm^2/s, corresponding to ∼1.8% of the flux observed from the Crab Nebula. The data show no evidence for significant variability on any time scale. The observed spectrum is characterized by a hard power law (Γ=2.50±0.19stat±0.10syst) from 500GeV to ∼15TeV. The high-energy range and hardness of the observed spectrum, coupled with the object's relatively large redshift (z=0.1396), enable the strongest constraints so far on the density of the Extragalactic Background Light (EBL) in the mid-infrared band. Assuming that the emitted spectrum is not harder than Γint≃1.5, the HESS data support an EBL spectrum ∝λ–1 and density close to the lower limit from source counts measured by Spitzer, confirming the previous indications from the HEGRA data of 1ES1426+428 (z=0.129). Irrespective of the EBL models used, the intrinsic spectrum of 1ES0229+200 is hard, thus locating the high-energy peak of its spectral energy distribution above a few TeV.

Abstract Copyright: ∼

Journal keyword(s): galaxies: BL lacertae objects: individual: 1ES0229+200 - gamma rays: observations

Simbad objects: 6

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Number of rows : 6
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 RX J0232.8+2017 BLL 02 32 48.6148874688 +20 17 17.486717388     18.00 13.96   ~ 387 1
2 HESS J0232+202 gam 02 32 53.2 +20 16 21           ~ 3 1
3 M 1 SNR 05 34 31.8 +22 01 03           ~ 6516 1
4 PMN J1103-2329 BLL 11 03 37.6150845072 -23 29 31.203773520   17.00 16.55 16.61   ~ 405 1
5 RX J1428.5+4240 BLL 14 28 32.6090008440 +42 40 21.048123396   16.95 16.45 14.4   ~ 549 1
6 QSO B2356-309 BLL 23 59 07.9034996184 -30 37 40.671098544   18.414 16.44 16.795   ~ 318 2

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