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Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Experimentelle Elementarteilchenphysik

Humboldt-Universität zu Berlin | Mathematisch-Naturwissen­schaft­liche Fakultät | Institut für Physik | Experimentelle Elementarteilchenphysik | H.E.S.S. | Talks & Papers | Discovery of VHE gamma-rays from the high-frequency-peaked BL Lacertae object RGB J0152+017

The H Collaboration (2008)

Discovery of VHE gamma-rays from the high-frequency-peaked BL Lacertae object RGB J0152+017

aap, 481:L103-L107.

Aims: The BL Lac object RGB J0152+017 (z=0.080) was predicted to be a very high-energy (VHE; >100 GeV) gamma-ray source, due to its high X-ray and radio fluxes. Our aim is to understand the radiative processes by investigating the observed emission and its production mechanism using the High Energy Stereoscopic System (HESS) experiment. Methods: We report recent observations of the BL Lac source RGB J0152+017 made in late October and November 2007 with the HESS array consisting of four imaging atmospheric Cherenkov telescopes. Contemporaneous observations were made in X-rays by the Swift and RXTE satellites, in the optical band with the ATOM telescope, and in the radio band with the Nançay Radio Telescope. Results: A signal of 173 gamma-ray photons corresponding to a statistical significance of 6.6sigma was found in the data. The energy spectrum of the source can be described by a powerlaw with a spectral index of Gamma=2.95±0.36^stat± 0.20^syst. The integral flux above 300 GeV corresponds to 2% of the flux of the Crab nebula. The source spectral energy distribution (SED) can be described using a two-component non-thermal synchrotron self-Compton (SSC) leptonic model, except in the optical band, which is dominated by a thermal host galaxy component. The parameters that are found are very close to those found in similar SSC studies in TeV blazars. Conclusions: RGB J0152+017 is discovered as a source of VHE gamma-rays by HESS The location of its synchrotron peak, as derived from the SED in Swift data, allows clear classification as a high-frequency-peaked BL Lac (HBL).

Provided by the SAO/NASA Astrophysics Data System