Do stellar-mass and super-massive black holes have similar dining habits?

R Arcodia,K Nandra,G Ponti,A Merloni

doi:10.1051/0004-6361/202037969

Abstract

Over the years, numerous attempts have been made to connect the phenomenology and physics of mass accretion onto stellar-mass and super-massive black holes in a scale-invariant fashion. In this paper, we explore this connection at the radiatively efficient (and non-jetted) end of accretion modes by comparing the relationship between the luminosity of the accretion disc and corona in the two source classes. Motivated by the apparently tight relationship between these two quantities in active galactic nuclei (AGNs), we analyse 458 RXTE-PCA archival observations of the X-ray binary (XRB) GX 339–4, using this object as an exemplar for the properties of XRBs in general. We focus on the soft and soft-intermediate states, which have been suggested to be analogous to radiatively efficient AGNs. The observed scatter in the logLdisc − logLcoronarelationship of GX 339–4 is high (∼0.43 dex) and significantly larger than in a representative sample of radiatively efficient, non- or weakly jetted AGNs (∼0.30 dex). At first glance, this would appear contrary to the hypothesis that the systems simply scale with mass. On the other hand, we also find that GX 339–4 and our AGN sample show different accretion rate and power-law index distributions, with the latter in particular being broader in GX 339–4 (dispersion of ∼0.16 cf. ∼0.08 for AGN). GX 339–4 also shows an overall softer slope, with a mean value of ∼2.20 as opposed to ∼2.07 for the AGN sample. Remarkably, once similarly broad Γ andṁdistributions are selected, the AGN sample overlaps nicely with GX 339–4 observations in the mass-normalised logLdisc − logLcoronaplane, with a scatter of ∼0.30 − 0.33 dex in both cases. This indicates that a mass-scaling of properties might hold after all, with our results being consistent with the disc-corona systems in AGNs and XRBs exhibiting the same physical processes, albeit under different conditions for instance in terms of temperature, optical depth and/or electron energy distribution in the corona, heating-cooling balance, coronal geometry and/or black hole spin.

Highlights

IntroductionThere is evidence that the phenomenology of how black holes (BHs) accrete matter is somewhat analogous
An intriguing and long-standing question exists as to whether the accretion flow around black holes (BHs) is similar among masses (m = MBH/M ) that are orders of magnitude apart, ranging from X-ray binaries (XRBs; m ∼ 5−15; Casares et al 2017) to active galactic nuclei (AGNs; m ∼ 106−1010; Padovani et al 2017)
In Appendix C we further discussed our choice and we presented our tests with BHSPEC performed in order to verify the impact of a different disc model on our results

Summary

Introduction

There is evidence that the phenomenology of how BHs accrete matter is somewhat analogous Noda & Done 2018; Vahdat Motlagh et al 2019) were connected to XRBs in the soft states (SS; Maccarone et al 2003) and soft-intermediate states (SIMS; Sobolewska et al 2009). This picture has been confirmed and expanded by Körding et al (2006) to include the analogy between hard-intermediate states in XRBs, where there is some disc contribution but the radio jet is present as well, and radiatively efficient radio-loud quasars; and by analysing AGNs

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Results

Discussion

Conclusion