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 ($\alpha_{ \rm OX}$) and the monochromatic luminosity at $2500~\r{ A}$ ($L_{ \rm 2500~\r{ A}}$) for both the super- and sub-Eddington subsamples. The best-fit $\alpha_{ \rm OX}-L_{ \rm 2500~\r{ A}}$ 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 $\alpha_{ \rm OX}$ on both the Eddington ratio ($L_{ \rm Bol}/L_{ \rm Edd}$) and black hole mass ($M_{ \rm BH}$) parameters for our full sample. A multi-variate linear regression analysis yields $\alpha_{ \rm OX}=-0.13 { \rm log}(L_{ \rm Bol}/L_{ \rm Edd})-0.10 { \rm log}M_{ \rm BH}-0.69$, with a scatter similar to that of the $\alpha_{ \rm OX}-L_{ \rm 2500~\r{ A}}$ relation. The hard (rest-frame $>2\rm ~keV$) X-ray photon index ($\Gamma$) is strongly correlated with $L_{ \rm Bol}/L_{ \rm Edd}$ 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.
Categories: astro-ph.GA astro-ph.HE