dc.contributor.author | Acero, F. | en_US |
dc.contributor.author | Büsching, I. | en_US |
dc.contributor.author | Davids, I.D. | en_US |
dc.contributor.author | De Jager, O.C. | en_US |
dc.contributor.author | Holleran, M. | |
dc.contributor.author | Raubenheimer, B.C. | |
dc.contributor.author | Venter, C. | |
dc.contributor.author | H.E.S.S. Collaboration | |
dc.date.accessioned | 2012-02-29T09:51:58Z | |
dc.date.available | 2012-02-29T09:51:58Z | |
dc.date.issued | 2010 | en_US |
dc.identifier.citation | Acero, F. et al. 2010. PKS 2005-489 at VHE: four years of monitoring with HESS and simultaneous multi-wavelength observations. Astronomy & astrophysics, 511: Article no A52. [https://doi.org/10.1051/0004-6361/200913073] | en_US |
dc.identifier.issn | 0004-6361 | en_US |
dc.identifier.issn | 1432-0746 (Online) | en_US |
dc.identifier.uri | http://hdl.handle.net/10394/6128 | |
dc.identifier.uri | https://doi.org/10.1051/0004-6361/200913073 | |
dc.identifier.uri | https://www.aanda.org/articles/aa/pdf/2010/03/aa13073-09.pdf | |
dc.description.abstract | Aims. Our aim is to study the very high energy (VHE; E>100 GeV) γ-ray emission from BL Lac objects and the evolution in time of their broad-band spectral energy distribution (SED).
Methods. VHE observations of the high-frequency peaked BL Lac object PKS 2005-489 were made with the High Energy Stereoscopic System (HESS) from 2004 through 2007. Three simultaneous multi-wavelength campaigns at lower energies were performed during the HESS data taking, consisting of several individual pointings with the XMM-Newton and RXTE satellites.
Results. A strong VHE signal, ~17σ total, from PKS 2005-489 was detected during the four years of HESS observations (90.3 h live time). The integral flux above the average analysis threshold of 400 GeV is ~3% of the flux observed from the Crab Nebula and varies weakly on time scales from days to years. The average VHE spectrum measured from ~300 GeV to ~5 TeV is characterized by a power law with a photon index, . At X-ray energies the flux is observed to vary by more than an order of magnitude between 2004 and 2005. Strong changes in the X-ray spectrum () are also observed, which appear to be mirrored in the VHE band.
Conclusions. The SED of PKS 2005-489, constructed for the first time with contemporaneous data on both humps, shows significant evolution. The large flux variations in the X-ray band, coupled with weak or no variations in the VHE band and a similar spectral behavior, suggest the emergence of a new, separate, harder emission component in September 2005 | |
dc.language.iso | en | |
dc.publisher | EDP Sciences | en_US |
dc.subject | Galaxies: active | |
dc.subject | BL Lacertae objects: individual: PKS 2005-489 | |
dc.subject | Gamma rays: galaxies | |
dc.subject | X-rays: individuals: PKS 2005-489 | |
dc.title | PKS 2005-489 at VHE: four years of monitoring with HESS and simultaneous multi-wavelength observations | en_US |
dc.contributor.researchID | 10859748 - Holleran, Mathew | |
dc.contributor.researchID | 12006653 - Venter, Christo | |
dc.contributor.researchID | 10179240 - Raubenheimer, Barend Christoffel | |
dc.contributor.researchID | 13235176 - Büsching, Ingo | |
dc.contributor.researchID | 10065857 - De Jager, Ocker Cornelis | |
dc.contributor.researchID | 13146629 - Davids, Isak Delberth | |