Discovery of Very High Energy gamma-Ray Emission from Centaurus a with H.E.S.S.

Discovery of Very High Energy gamma-Ray Emission from Centaurus a with H.E.S.S.

We report the discovery of faint very high energy (VHE; E > 100 GeV) gamma-ray emission from the radio galaxy Centaurus A in observations performed with the High Energy Stereoscopic System (H.E.S.S.) experiment, an imaging atmospheric Cherenkov telescope array consisting of four telescopes lo...

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Main Authors: Aharonian, F., Akhperjanian, A., Anton, G., De Almeida, U., Bazer-Bachi, A., Becherini, Y., Behera, B., Benbow, W., Bernlöhr, K., Boisson, C., Bochow, A., Borrel, V., Brion, E., Brucker, J., Brun, P., BüHLER, R., Bulik, T., Büsching, I., Boutelier, T., Chadwick, P., Charbonnier, A., Chaves, R., Cheesebrough, A., Chounet, L., Clapson, A., Coignet, G., Dalton, M., Daniel, M., Davids, I., Degrange, B., Deil, C., Dickinson, H., Djannati-Ataï, A., Domainko, W., Drury, L., Dubois, F., Dubus, G., Dyks, J., Dyrda, M., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Füling, M., Gabici, S., Gallant, Y., Gerard, L., Giebels, B., Glicenstein, J., Glück, B., Goret, P., Göhring, D., Häuser, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, P., Horns, D., Jacholkowska, A., De Jager, O., Jahn, C., Jung, I., Katarzynski, K., Katz, U., Kaufmann, S., Kendziorra, E., Kerschhaggl, M., Khangulyan, D., Khélifi, B., Keogh, D., Kluzniak, W., Kneiske, T., Komin, N., Kosack, K., Lamanna, G., Latham, I., Lenain, J., Lohse, T., Marandon, V., Martin, J., Martineau-Huynh, O., Marcowith, A., Maurin, D., McComb, T., Medina, C., Moderski, R., Moulin, E., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Niemiec, J., Nolan, S., Ohm, S., Olive, J., de Oña Wilhelmi, E., Orford, K., Ostrowski, M., Panter, M., Paz Arribas, M., Pedaletti, G., Pelletier, G., Petrucci, P., Pita, S., Pühlhofer, G., Punch, M., Quirrenbach, A., Raubenheimer, B., Raue, M., Rayner, S., Renaud, M., Rieger, F., Ripken, J., Rob, L., Rosier Lees, S., Rowell, G., Rudak, B., Rulten, C., Ruppel, J., Sahakian, V., Santangelo, A., Schlickeiser, R., Schöck, F., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sikora, M., Skilton, J., Sol, H., Spangler, D., Stawarz, L., Steenkamp, R., Stegmann, C., Superina, G., Szostek, A., Tam, P., Tavernet, J., Terrier, R., Tibolla, Omar, Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Venter, L., Vialle, J., Vincent, P., Vink, J., Vivier, M., Volk, H., Volpe, F., Wagner, S., Ward, M., Zdziarski, A., Zech, A.
Format: Journal Article
Published: Institute of Physics Publishing 2009
Online Access:http://iopscience.iop.org/1538-4357/695/1/L40/pdf/apjl_695_1_40.pdf
http://hdl.handle.net/20.500.11937/23667
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Summary:We report the discovery of faint very high energy (VHE; E > 100 GeV) gamma-ray emission from the radio galaxy Centaurus A in observations performed with the High Energy Stereoscopic System (H.E.S.S.) experiment, an imaging atmospheric Cherenkov telescope array consisting of four telescopes located in Namibia. Centaurus A has been observed for more than 120 hr. A signal with a statistical significance of 5.0sigma is detected from the region including the radio core and the inner kpc jets. The integral flux above an energy threshold of ~250 GeV is measured to be 0.8% of the flux of the Crab Nebula (apparent luminosity: L(>250 GeV) ˜2.6 × 1039 erg s-1, adopting a distance of 3.8 Mpc). The spectrum can be described by a power law with a photon index of 2.7 ± 0.5stat ± 0.2sys. No significant flux variability is detected in the data set. However, the low flux only allows detection of variability on the timescale of days to flux increments above a factor of ~15-20 (3sigma and 4sigma, respectively). The discovery of VHE gamma-ray emission from Centaurus A reveals particle acceleration in the source to >TeV energies and, together with M 87, establishes radio galaxies as a class of VHE emitters.

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