Description
Through the years several attempts have been made to connect the phenomenology and physics of mass accretion around stellar-mass and super-massive black holes in a scale-invariant fashion. We here try to improve on this connection for the radiatively-efficient end of accretion modes, testing the disk-corona energetic interplay in soft and soft-intermediate states of the X-ray binary (XRB) GX 339-4 with 458 RXTE-PCA archival observations. The observed scatter in the $\log L_{disk}- \log L_{corona}$ plane of XRBs is very high ($\sim0.43\,$dex) and significantly larger than in representative samples of radiatively-efficient Active Galactic Nuclei (AGN, typically $\sim0.30\,$dex). This is likely related to the XRBs power-law index distribution being broader (dispersion of $\sim0.16$ as opposed to $\sim0.08$), even accounting for the measured uncertainties, and shifted to softer slopes (mean value of $\sim2.20$ as opposed to $\sim2.07$). It is notwithstanding remarkable that once similarly broad $\Gamma$ and $\dot{m}$ distributions are selected, AGN and XRBs overlap quite nicely in the mass-normalised $\log L_{disk}- \log L_{corona}$ plane with a scatter of $\sim0.30-0.33\,$dex. Thus, as far as the disk-corona interplay is concerned, it seems more relevant how similarly diverse the disk-corona systems are rather than how different the typical one is between the two source classes. However, this common scatter is still higher than $\leq0.20\,$dex, namely what is claimed to be the real physical scatter in the $\log L_{disk}- \log L_{corona}$ in AGN. We conclude that either the two systems are not entirely analogous and should not be scaled without caution, or they are indeed similar, and thus the physical scatter of the disk-corona emission in AGN is not as low as we think, with insightful implications for both accretion physics and quasars cosmology. This analogy will be further pursued studying the AGN population in the eFEDS field with eROSITA in combination with optical spectroscopy and radio coverage adding a third dimension to reach a more comprehensive view on the disk-corona-jet plane.
| Presenter status | eROSITA-DE consortium member |
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