2025/01/26 by Mallick, Labani, Pinto, Ciro, Tomsick, John +6
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Space Physics (physics.space-ph)
paper · doi:10.48550/arxiv.2501.15380
Understanding the nature of the accretion disk, its interplay with the X-ray corona, and assessing black hole spin demographics are some open challenges in astrophysics. In this work, we examine the predictions of the standard α-disk model, origin of the soft X-ray excess, and measure the black hole spin parameter by applying the updated high-density disk reflection model to the XMM-Newton/NuSTAR broadband (0.3-78 keV) X-ray spectra of a sample of Type-1 AGN. Our Bayesian analysis confirms that the high-density relativistic reflection model with a broken power-law emissivity profile can simultaneously fit the soft X-ray excess, broad iron K line, and Compton hump for ∼70% of the sample, while an additional warm Comptonization model is still required to describe the observed soft X-ray excess for the remaining sources. Our first-ever calculation of the disk-to-corona power transfer fraction reveals that the fraction of power released from the accretion disk into the hot corona can have diverse values, the sample median of which is 0.7-0.4+0.2. We find that the transferred power from the accretion disk can potentially soften the X-ray spectrum of the hot corona. The median values of the hot coronal temperature and optical depth for the sample are estimated to be 63-11+23 keV and 0.85-0.27+0.12, respectively. Finally, through joint XMM-Newton+NuSTAR relativistic reflection spectroscopy, we systematically constrain the black hole spin parameter across the broad range of black hole masses, log(M\rm BH/M\odot) ∼ 5.5-9.0, and increase the available spin measurements in the AGN population by ∼20%.