Revisit the fundamental plane of black-hole activity from sub-Eddington to quiescent state

Qingwen Wu; Ai-Jun Dong

doi:10.1093/mnras/stv1801

paper

Revisit the fundamental plane of black-hole activity from sub-Eddington to quiescent state

arXiv:1509.05088 · doi:10.1093/mnras/stv1801

Abstract

It is very controversial whether radio--X-ray correlation as defined in LH state of XRBs can extend to quiescent state (e.g., X-ray luminosity less than a critical value of $L_{X, c} \sim 1 0^{- 5.5} L_{Edd}$ ) or not. In this work, we collect a sample of XRBs and low luminosity active galactic nuclei (LLAGNs) with wide distribution of Eddington ratios to reexplore the fundamental plane between 5 GHz radio luminosity, $L_{R}$ , 2-10 keV X-ray luminosity, $L_{X}$ , and black hole (BH) mass, $M_{BH}$ , namely $lo g L_{R} = ξ_{X} lo g L_{X} + ξ_{M} lo g M_{BH} + constant$ . For the whole sample, we confirm the former fundamental plane of Merloni et al. and Falcke et al. that $ξ_{X} \sim 0.6$ and $ξ_{M} \sim 0.8$ even after including more quiescent BHs. The quiescent BHs follow the fundamental plane very well, and, however, FR I radio galaxies follow a steeper track comparing other BH sources. After excluding FR Is, we investigate the fundamental plane for BHs in quiescent state with $L_{X} < L_{X, c}$ and sub-Eddington BHs with $L_{X} > L_{X, c}$ respectively, and both subsamples have a similar slope, $ξ_{X} \sim 0.6$ , which support that quiescent BHs may behave similar to those in low-hard state. We further select two subsamples of AGNs with BH mass in a narrow range (FR Is with $M_{BH} = 1 0^{8.8 \pm 0.4}$ and other LLAGNs with $M_{BH} = 1 0^{8.0 \pm 0.4}$ ) to simulate the behavior of a single supermassive BH evolving from sub-Eddington to quiescent state. We find that the highly sub-Eddington sources with $L_{X} / L_{Edd} \sim 1 0^{- 6} - 1 0^{- 9}$ still roughly stay on the extension of radio--X-ray correlation as defined by other sub-Eddington BHs. Our results are consistent with several recent observations in XRBs that the radio--X-ray correlation as defined in low-hard state can extend to highly sub-Eddington quiescent state.

8 pages, 3 figures, MNRAS 453,3447-3454, 2015

Revisit the fundamental plane of black-hole activity from sub-Eddington to quiescent state

Abstract

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