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 \sim 56 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 \sim 40 and \sim 330 eV , together with a power-law .
Alternatively , a Comptonisation model also provides a good fit , with a mean electron temperature of \sim 350 eV , although this value is higher when the soft excess is more luminous over the 0.5–10 keV energy band .
In the RGS spectrum of 3C 273 , a strong detection of the O vii He \alpha 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 et al .
( 2003 ) and Rasmussen et al .
( 2003 ) .