Keele Research Repository

We report on a timing analysis of a new ∼630 ks XMM–Newton observation of the quasar, PG 1211+143. We find a well-defined X-ray power spectrum with a well-detected bend at ∼7 × 10−5 Hz, consistent with the established tbend–MBH correlation for luminous, accreting black holes. We find the linear rms–flux relation commonly observed in accreting black hole systems and investigate the energy-dependence of the rms. The fractional rms is roughly constant with energy on short time-scales (<1 d; within observations) whereas there is enhanced soft band variability on long time-scales (between observations typically spaced by a few days). Additionally, we also report on the optical–UV variability using the Optical Monitor on-board XMM–Newton and a ∼2-month-long overlapping monitoring programme with Swift. We find that, although there is little UV variability within observations (<1 d), UV variations of a few per cent exist on time-scales of ∼days–weeks.