Negative X-ray reverberation time delays from MCG-6-30-15 and Mrk766

Abstract

We present an X-ray time lag analysis, as a function of Fourier frequency, for MCG-6-30-15 and Mrk766 using long-termXMM-Newtonlight curves in the 0.5-1.5 and the 2-4keV energy bands, together with some physical modelling of the corresponding time lag spectra. Both the time lag spectra of MCG-6-30-15 and Mrk766 show negative values (i.e. soft band variations lag behind the corresponding hard band variations) at high frequencies, around 10-3Hz, similar to those previously observed from 1H0707-495. The remarkable morphological resemblance between the time lag spectra of MCG-6-30-15 and Mrk766 indicate that the physical processes responsible for the observed soft time delays are very similar in the two sources, favouring a reflection scenario from material situated very nearby to the central black hole. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.