Astrophys. J., 910, 103-103 (2021/April-1)
On the observational difference between the accretion disk-corona connections among super- and sub-Eddington accreting active galactic nuclei.
LIU H., LUO B., BRANDT W.N., BROTHERTON M.S., GALLAGHER S.C., NI Q., SHEMMER O. and TIMLIN J.D.
Abstract (from CDS):
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 (αOX) and the monochromatic luminosity at 2500 Å (L2500Å) for both the super- and sub-Eddington subsamples. The best-fit αOX-L2500Å 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 αOX on both the Eddington ratio (LBol/LEdd) and black hole mass (MBH) parameters for our full sample. A multivariate linear regression analysis yields αOX=-0.13log(LBol/LEdd)-0.10logMBH-0.69, with a scatter similar to that of the αOX-L2500Å relation. The hard (rest-frame >2 keV) X-ray photon index (Γ) is strongly correlated with LBol/LEdd 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.
© 2021. The American Astronomical Society. All rights reserved.
Accretion - X-ray active galactic nuclei - Radio quiet quasars
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