Abstract
The HESS experiment (High Energy Stereoscopic System), consisting of four imaging atmospheric Cherenkov telescopes (IACTs) in Namibia, has observed many extragalactic objects in the search for very high energy (VHE) γ-ray emission. These objects include active galactic nuclei (AGN), notably Blazars, Seyferts, radio galaxies, starburst galaxies and others. Beyond the established sources, γ-ray emission has been detected for the first time from several of these objects by HESS, and their energy spectra and variability characteristics have been measured. Multi-wavelength campaigns, including X-ray satellites, radio telescopes, and optical observations, have been carried out for AGNs, in particular for PKS 2155-304, H 2356-309 and 1ES 1101-232, for which the implications concerning emission models are presented. Also results from the investigations of VHE flux variability from the giant radio galaxy M 87 are shown.
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Aharonian, F.A., et al.: TeV gamma rays from the blazar H1426+428 and the diffuse extragalactic background radiation. Astron. Astrophys. 384, L23–L26 (2002)
Aharonian, F.A., et al.: Is the giant radio galaxy M 87 a TeV gamma-ray emitter?. Astron. Astrophys. 403, L1–L5 (2003)
Aharonian, F.A., et al. (HESS Collaboration): HESS observations of PKS2155-304. Astron. Astrophys. 430, 865–875 (2005a)
Aharonian, F.A., et al. (HESS Collaboration): Discovery of VHE gamma-rays from PKS2005-489. Astron. Astrophys. 436, L17–L20 (2005b)
Aharonian, F.A., et al. (HESS Collaboration): Observations of selected AGN with HESS. Astron. Astrophys. 441, 465–472 (2005c)
Aharonian, F.A., et al. (HESS Collaboration): A search for very high energy gamma-ray emission from the starburst galaxy NGC 253 with HESS. Astron. Astrophys. 442, 177–183 (2005d)
Aharonian, F.A., et al. (HESS Collaboration): Multi-wavelength observations of PKS 2155-304 with HESS. Astron. Astrophys. 442, 895–907 (2005e)
Aharonian, F.A., et al.: Evidence for VHE gamma-ray emission from the distant BL Lac PG 1553+113. Astron. Astrophys. 448, L19–L23 (2006a)
Aharonian, F.A., et al.: A low level of extragalactic background light as revealed by gamma-rays from blazars. Nature 440, 1018–1021 (2006b)
Aharonian, F.A., et al.: Stepping up in redshift: detection of VHE gamma-ray emission from 1ES 1101-232 with HESS and broadband characterisation (2006c, in preparation)
Aharonian, F.A., et al.: Discovery of fast variability of TeV γ-ray emission from the giant radio galaxy M 87. Science 314, 1424–1427 (2006d)
Aharonian, F.A., et al.: Discovery of very high energy γ-ray emission from the BL Lac object H2356-309 with the HESS Cherenkov telescopes. Astron. Astrophys. 455, 461–466 (2006e)
Bai, J.M., Lee, M.G.: Are Centaurus A and M 87 TeV gamma-ray sources?. Astrophys. J. 549, L173–L177 (2001)
Beilicke, M., Benbow, W., Cornils, R., et al.: Observation of the giant radio galaxy M 87 at TeV energies with the HESS Cherenkov telescopes. In: Proc. of the 29th ICRC, Pune, vol. 4, pp. 299–302 (2005)
Benbow, W.: Cosmic ray backgr. reject. & spectral analysis techniques. In: Proc. Towards a Network of Atmospheric Cherenkov Detectors VII Palaiseau, p. 163 (2005)
Biermann, P.L., et al.: Origin of the highest energy cosmic rays. Nucl. Phys. Suppl. 87, 417–419 (2000)
Costamante, L. doi:10.1007/s10509-007-9418-7 (2007)
Domingo-Santamaria, E., Torres, D.F.: High energy γ-ray emission from the starburst nucleus of NGC 253. Astron. Astrophys. 444, 403–415 (2005)
Götting, N., et al.: Recent results from HEGRA. Eur. Phys. J. C 33, 932–934 (2004)
Grindlay, J.E., et al.: Evidence for the detection of gamma rays from Centaurus A at gamma-ray energies above 300 GeV. Astrophys. J. 197, L9–L12 (1975)
Harris, D.E., et al.: The outburst of HST-1 in the M 87 jet. Astrophys. J. 640, 211–218 (2006)
Hofmann, W.: HESS highlights. In: Proc. of the 29th International Cosmic Ray Conference, Pune vol. 10, pp. 97–114 (2005)
Le Bohec, S., et al.: Observation of M 87 at 400 GeV with the whipple 10 meter telescope. Astrophys. J. 610, 156–160 (2004)
Macchetto, F., et al.: The supermassive black hole of M87 an the kinematics of its associated gaseous disk. Astrophys. J. 489, 579–600 (1997)
Owen, F.N., Eilek, J.A., Kassim, J.A.: M 87 at 90 centimeters: a different picture. Astrophys. J. 543, 611–619 (2000)
Punch, M., et al.: Detection of TeV photons from the active galaxy Markarian 421. Nature 358, 477–478 (1992)
Sreekumar, P., et al.: GeV emission from the nearby radio galaxy Centaurus A. Astropart. Phys. 11, 221–223 (1999)
Völk, H.J., Aharonian, F.A., Breitschwerdt, D.: The nonthermal energy content and gamma-ray emission of starburst galaxies and clusters of galaxies. Space Sci. Rev. 75, 279–297 (1996)
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Beilicke, M. HESS observations of extragalactic objects. Astrophys Space Sci 309, 139–145 (2007). https://doi.org/10.1007/s10509-007-9400-4
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DOI: https://doi.org/10.1007/s10509-007-9400-4