Probing Supermassive Black Hole Spins via X-ray Spectroscopy

The X-ray relativistically broadened fluorescent iron line and the Compton hump reflected from the innermost accretion flows around a supermassive black hole (SMBH) can be used to probe black hole spin rates. In particular, X-ray spectroscopy helps us measure the SMBH spins in nearby Seyfert 1 galaxies whose central innermost regions are not largely blocked by the dusty torus. In this study, a MCMC-based method is employed to probe the best-fit parameters of a relativistic reflection model in X-ray archival data of a sample of nearby Seyfert 1 active galaxies observed by the XMM-Newton and NuSTAR space telescopes. Future high-resolution X-ray spectroscopic observations with the Advanced Telescope for High-ENergy Astrophysics (Athena) as demonstrated by simulations will certainly allow us to put better constraints on SMBH spins, which have profound implications for our understanding of the mechanism behind ultra-fast outflows launched at the centers of Seyfert 1 galaxies.