Testing strong gravity in the NLS1 PKS 0558-504

We propose to observe the radioloud NLS1 galaxy PKSvirgul0558504 with XMM for fiveorbits (650 ksec). There has been evidence for QPOs with time scales of 7 ksecand 21 ksec in previous short XMM observations. These time scales are near afrequency ratio of 3:1, a well known result from Galactic Black Hole binaries.The main aims of the proposed XMM observation are to confirm the presence of aQPO like feature at 7 ksec, to search for evidence for the associated 21 ksecmodulation, and for the third possible time scale of 14 ks (the one with a 3:2frequency ratio). Confirmation of the presence of these time scales will providea unique probe of strong gravity in the vicinity of an AGN black hole. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]