"On the Observational Difference between the Accretion Disk-Corona Conn" by Hezhen Liu, B. Luo et al.

Physics and Astronomy Publications

Title

On the Observational Difference between the Accretion Disk-Corona Connections among Super- And Sub-Eddington Accreting Active Galactic Nuclei

Authors

Hezhen Liu, Nanjing University
B. Luo, Nanjing University
W. N. Brandt, Pennsylvania State University
Michael S. Brotherton, University of Wyoming
Sarah C. Gallagher, University of Western OntarioFollow
Q. Ni, Pennsylvania State University
Ohad Shemmer, University of North Texas
J. D. Timlin, Pennsylvania State University

Document Type

Article

Publication Date

4-1-2021

Journal

Astrophysical Journal

Volume

910

Issue

URL with Digital Object Identifier

10.3847/1538-4357/abe37f

Abstract

We present a systematic X-ray and multiwavelength study of a sample of 47 active galactic nuclei (AGNs) with reverberation mapping measurements. This sample includes 21 super-Eddington accreting AGNs and 26 sub-Eddington accreting AGNs. Using high-state observations with simultaneous X-ray and UV/optical measurements, we investigate whether super-Eddington accreting AGNs exhibit different accretion disk-corona connections compared to sub-Eddington accreting AGNs. We find tight correlations between the X-ray-to-UV/optical spectral slope parameter (α OX) and the monochromatic luminosity at 2500 Å (L 2500Å) for both the super- and sub-Eddington subsamples. The best-fit α OX-L 2500Å relations are consistent overall, indicating that super-Eddington accreting AGNs are not particularly X-ray weak in general compared to sub-Eddington accreting AGNs. We find dependences of α OX on both the Eddington ratio (L Bol/L Edd) and black hole mass (M BH) parameters for our full sample. A multivariate linear regression analysis yields, with a scatter similar to that of the α OX-L 2500Å relation. The hard (rest-frame >2 keV) X-ray photon index (Γ) is strongly correlated with L Bol/L Edd for the full sample and the super-Eddington subsample, but these two parameters are not significantly correlated for the sub-Eddington subsample. A fraction of super-Eddington accreting AGNs show strong X-ray variability, probably due to small-scale gas absorption, and we highlight the importance of employing high-state (intrinsic) X-ray radiation to study the accretion disk-corona connections in AGNs.