X -ray Variability ofthe Seyfert 1 M arkarian 335:Power Spectrum and Tim e Lags

A B ST R A C T Toinvestigatefurtherthecom parison between AGN and blackholeX-ray binaries,we have studied the m ain X-ray variability propertiesofthe Seyfert1 Galaxy M rk 335. W e putparticularem phasison the X-ray tim e lags,which isa potentially im portant diagnosticofphysicalm odels.From a 100ksecobservation by XM M -Newton weshow thatthe powerspectrum ofthissource iswelltted by a bending powerlaw m odel, and the bend tim e-scale Tb isprecisely atthe value predicted by the Tb vsHline- width relation ofM cHardy etal.Variationsin dierentenergy bandsshow tim e-scale dependenttim e lags,wherehigherenergy bandslag lowerones.The lag, �,variesas a function oftheFourierfrequency, f,ofthevariability com ponentin thelightcurves as � / f 1 atlow frequencies,butthere isa sharp cut-oin the lagsata frequency closeto thebend frequency in thepowerspectrum .Sim ilarbehaviourisseen in black hole X-ray binary system s.The length ofthe tim e lags increases continuously with energy separation,in an alm ostlog-linearrelation.W e show thatthe lag spectra can be produced by uctuations propagating through the accretion ow as long as the energy spectrum oftheX-ray em itting region hardenstowardsthecentre. K ey w ords: Galaxies:active