XMM-Newton observations of 3C 273

A series of nine XMM-Newton observations of the radio-loud quasar 3C 273 are presented, concentrating mainly on the soft excess. Although most of the individual observations do not show evidence for iron emission, co-adding them reveals a weak, broad line (EW similar to56 eV). The soft excess component is found to vary, confirming previous work, and can be well fitted with multiple blackbody components, with temperatures ranging between similar to40 and similar to330 eV, together with a power law. Alternatively, a Comptonization model also provides a good fit, with a mean electron temperature of similar to350 eV, although this value is higher when the soft excess is more luminous over the 0.5-10 keV energy band. In the reflection grating spectrometer spectrum of 3C 273, a strong detection of the O VII Healpha absorption line at zero redshift is made; this may originate in warm gas in the local intergalactic medium, consistent with the findings of both Fang, Sembach & Canizares and Rasmussen, Kahn Paerels.