X-RAY VARIABILITY OF ACTIVE GALACTIC NUCLEI IN THE SOFT AND HARD X-RAY BANDS

Abstract

We investigate the X-ray variability characteristics of hard X-ray selected\nAGNs (based on Swift/BAT data) in the soft X-ray band using the RXTE/ASM data.\nThe uncertainties involved in the individual dwell measurements of ASM are\ncritically examined and a method is developed to combine a large number of\ndwells with appropriate error propagation to derive long duration flux\nmeasurements (greater than 10 days). We also provide a general prescription to\nestimate the errors in variability derived from rms values from unequally\nspaced data. Though the derived variability for individual sources are not of\nvery high significance, we find that, in general, the soft X-ray variability is\nhigher than those in hard X-rays and the variability strengths decrease with\nenergy for the diverse classes of AGN. We also examine the strength of\nvariability as a function of the break time scale in the power density spectrum\n(derived from the estimated mass and bolometric luminosity of the sources) and\nfind that the data are consistent with the idea of higher variability at time\nscales longer than the break time scale.\n