X-Ray Spectral Complexity in Quasars

Abstract

We present a comprehensive multi-wavelength analysis of quasar sample identified by cross-matching the 3XMM-DR7 X-ray catalog with the SDSS-DR12 optical catalog. To obtain X-ray luminosities, we modeled the spectra of all sources while accounting for soft excess and absorption, and then computed the absorbed luminosities for the full sample. For a subset of 41 quasars with redshifts z < 0.5, we calculated K-corrected rest-frame optical luminosities using SDSS r-band magnitudes. We found a statistically significant linear correlation between X-ray and optical luminosities logLopt = (1.10 ± 0.07)logLX + (−37.55 ± 3.05) with a strong coefficient of determination (R2 = 0.55) and a highly significant p-value (p < 10−7). This result supports the disk–corona coupling model in active galactic nuclei, wherein optical/UV photons from the accretion disk are Compton upscattered into the X-ray regime by a hot corona.