XMM–Newton observations of 3C 273

ABSTRACT A series of nine XMM-Newton observations of the radio-loud quasar 3C 273 arepresented, concentrating mainly on the soft excess. Although most of the individ-ual observations do not show evidence for iron emission, co-adding them reveals aweak, broad line (EW ∼ 56 eV). The soft excess component is found to vary, con-firming previous work, and can be well fitted with multiple blackbody components,with temperatures ranging between ∼ 40 and ∼ 330 eV, together with a power-law.Alternatively, a Comptonisation model also provides a good fit, with a mean electrontemperature of ∼ 350 eV, although this value is higher when the soft excess is moreluminous over the 0.5–10 keV energy band. In the RGS spectrum of 3C 273, a strongdetection of the Ovii Heα absorption line at zero redshift is made; this may originatein warm gas in the local intergalactic medium, consistent with the findings of bothFang et al. (2003) and Rasmussen et al. (2003).Key words: galaxies: active – X-rays: galaxies – galaxies: individual: 3C 273