The X-ray monitoring of quasar 3C273

Abstract

XMM-Newton has observed the quasar 3C273 several times between 2000 June and 2005 July. In addition data of NASA's Rossi X-ray Timing Explorer is used. We present the results of this monitoring campaign.The X-ray spectrum of 3C273, in the energy regime of 0.2–100 keV, is believed to be composed of three components: a power law component above about 3 keV, a soft excess below about 2 keV, and an Fe-line. The Fe-line, detected in only a few observations of 3C273, is not detected significantly in individual XMM-observations. Only the 2000 June observations show evidence for a presence of a broad line feature. The high energy component above 3 keV is well described by a single power law model with varying indices and fluxes. The steeper spectra show significantly higher flux levels. The soft excess component below 2 keV also shows variations in flux and spectral slope. Different models are tested to identify the soft excess to be thermal or non-thermal emission.