Revisiting the "Fundamental Plane" of Black Hole Activity at Extremely Low Luminosities

Feng Yuan; Zhaolong Yu; Luis C. Ho

doi:10.1088/0004-637X/703/1/1034

paper

Revisiting the "Fundamental Plane" of Black Hole Activity at Extremely Low Luminosities

arXiv:0902.3704 · doi:10.1088/0004-637X/703/1/1034

Abstract

We investigate the origin of the X-ray emission in low-luminosity AGNs (LLAGNs). Yuan & Cui (2005) predicted that the X-ray emission should originate from jets rather than from an advection-dominated accretion flow (ADAF) when the X-ray luminosity $L_{X}$ of the source is below a critical value of $L_{X, crit} \approx 1 0^{- 6} L_{Edd}$ . This prediction implies that the X-ray spectrum in such sources should be fitted by jets rather than ADAFs. Furthermore, below $L_{X, crit}$ the correlation between radio ( $L_{R}$ ) and X-ray ( $L_{X}$ ) luminosities and the black hole mass ( $M$ )--the so-called fundamental plane of black hole activity--should deviate from the general correlation obtained by Merloni, Heinz & Di Matteo (2003) and become steeper. The Merloni et al. correlation is described by $log L_{R} = 0.6 log L_{X} + 0.78 log M + 7.33$ , while the predicted correlation is $log L_{R} = 1.23 log L_{X} + 0.25 log M - 13.45$ . We collect data from the literature to check the validity of these two expectations. We find that among the 16 LLAGNs with good X-ray and radio spectra, 13 are consistent with the Yuan & Cui prediction. For the 22 LLAGNs with $L_{X} < L_{X, crit}$ , the fundamental plane correlation is described by $log L_{R} = 1.22 log L_{X} + 0.23 log M - 12.46$ , also in excellent agreement with the prediction.

arXiv comment24 pages, 2 tables, 3 figures; accepted by ApJ

Revisiting the "Fundamental Plane" of Black Hole Activity at Extremely Low Luminosities

Abstract

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