62 articles – 637 Notices  [english version]
 HAL : in2p3-00024349, version 1
 arXiv : astro-ph/0506593
 Astronomy and Astrophysics 442 (2005) 895-907
 Multi-wavelength observations of PKS 2155-304 with H.E.S.S
 HESS Collaboration(s)
 (2005)
 The High Energy Stereoscopic System (H.E.S.S.) has observed the high-frequency peaked BL Lac object PKS2155-304 in 2003 between October 19 and November 26 in Very High Energy (VHE) $\gamma$-rays (E $\geq$ 160 GeV for these observations). Observations were carried out simultaneously with the Proportional Counter Array (PCA) on board the Rossi X-ray Timing Explorer satellite (RXTE), the Robotic Optical Transient Search Experiment (ROTSE) and the Nancay decimetric radiotelescope (NRT). Intra-night variability is seen in the VHE band, the source being detected with a high significance on each night it was observed. Variability is also found in the X-ray and optical bands on kilosecond timescales, along with flux-dependent spectral changes in the X-rays. The average H.E.S.S. spectrum shows a very soft power law shape with a photon index of 3.37 $\pm$ 0.07\${stat} \pm 0.10 {syst}. The energy outputs in the 2-10 keV and in the VHE gamma-ray range are found to be similar, with the X-rays and the optical fluxes at a level comparable to some of the lowest historical measurements, indicating that PKS2155-304 was in a low or quiescent state during the observations. Both a leptonic and a hadronic model are used to derive source parameters from these observations.
 Thème(s) : Physique/Astrophysique/Cosmologie et astrophysique extra-galactiquePlanète et Univers/Astrophysique
 Mot(s)-clé(s) : BL Lacertae objects: Individual: PKS 2155-304 – galaxie: active – gamma rays: observations – X-rays:galaxies – radiation mechanisms: non thermal
 Lien vers le texte intégral : http://fr.arXiv.org/abs/astro-ph/0506593
 in2p3-00024349, version 1 http://hal.in2p3.fr/in2p3-00024349 oai:hal.in2p3.fr:in2p3-00024349 Contributeur : Simone Lantz <> Soumis le : Lundi 30 Octobre 2006, 20:39:57 Dernière modification le : Lundi 30 Octobre 2006, 20:57:35