Abstract :
The X-ray emission from AGN is highly variable, on short (minutes/hours/day) and long (months/years) time scales. A particular characteristic of the observed variations is that the higher energy band variations are delayed with respect to lower energy photons. I will use archival Rossi X-ray Timing Explorer (RXTE) light curves and I will study the long term, frequency-dependent, X-ray time lags of the Seyfert galaxies MCG-6-30-15, Ark 564 and Mkn 766 in the 2-4, 4-7, and 7-10 keV bands. The main objective of this project is to investigate how these delays compare with the results from the model fitting of the time lags at higher frequencies.
