Speaker
Description
We present a study of the ensemble X-ray variability of Active Galactic Nuclei (AGN) over a large range of timescales (20 ks ≤ T ≤ 14 yrs), redshift (0 ≤ z ≲ 3), luminosities ($10^{40} \leq L_X \leq 10^{46}\ \mbox{erg s}^{−1}$) and black hole (BH) masses $10^6≤M_⊙≤10^9$). Through the use of the "variance–frequency diagram", as a viable alternative to the power spectral density (PSD), we show that the data collected from archival observations and previous literature studies are consistent with a universal PSD form which does not show evidence for systematic evolution of shape or amplitude with redshift or luminosity. We find new evidence that the PSD bend
frequency depends on BH mass and, possibly, on accretion rate. We will discuss the implications for current and future AGN population and cosmological studies
