A Fundamental Plane of black hole activity

Abstract

We examine the disc–jet connection in stellar mass and supermassive black holes by investigating the properties of their compact emission in the X‐ray and radio bands. We compile a sample of ∼100 active galactic nuclei with measured masses, 5‐GHz core emission, and 2–10 keV luminosities, together with eight galactic black holes with a total of ∼50 simultaneous observations in the radio and X‐ray bands. Using this sample, we study the correlations between the radio (LR) and the X‐ray (LX) luminosity and the black hole mass (M). We find that the radio luminosity is correlated with bothM and LX, at a highly significant level. In particular, we show that the sources define a ‘Fundamental Plane’ in the three‐dimensional (log LR, log LX, log M) space, given by log LR= (0.60+0.11−0.11) log LX+ (0.78+0.11−0.09) log M+ 7.33+4.05−4.07, with a substantial scatter of σR= 0.88. We compare our results to the theoretical relations between radio flux, black hole mass, and accretion rate derived by Heinz & Sunyaev. Such relations depend only on the assumed accretion model and on the observed radio spectral index. Therefore, we are able to show that the X‐ray emission from black holes accreting at less than a few per cent of the Eddington rate is unlikely to be produced by radiatively efficient accretion, and is marginally consistent with optically thin synchrotron emission from the jet. On the other hand, models for radiatively inefficient accretion flows seem to agree well with the data.

Spectral state transitions of the Ultraluminous X-ray Source IC 342 X-1

“…To confirm or deny the existence of a self-absorbed compact jet and investigate whether a relationship known as the fundamental plane (FP) of black hole activity (Merloni et al 2003;Falcke et al 2004) could be used to estimate the mass of the BH, we obtained simultaneous radio and X-ray observations of X-1.…”

Follow Up of GW170817 and Its Electromagnetic Counterpart by Australian-Led Observing Programmes

“…The compact radio emission detected by VLBA in the central region of NGC 4993 with a brightness temperature exceeding 10 6 K indicates the presence of a low-luminosity active galactic nucleus (LLAGN), allowing us to estimate the black hole mass using the fundamental plane of black hole activity (e.g. Plotkin et al 2012;Merloni, Heinz, & di Matteo 2003;Falcke, Körding, & Markoff 2004). The VLBA flux density was measured to be 0.22 ± 0.04 mJy at 8.7 GHz, which (assuming a flat spectral index) gives a 5-GHz radio luminosity of (2.1 ± 0.04) × 10 36 erg s −1 , while the X-ray luminosity as measured by SWIFT is 5.6 +2.4 −1.9 × 10 39 erg s −1 (Evans et al 2017).…”

Jets at lowest mass accretion rates

“…Such jets are known to emit across a broad range of the electromagnetic spectrum, from radio to X-rays, and perhaps even γ-rays. Sometimes jets can be imaged directly, but often their presence is inferred, such as from flat to slightly inverted spectral energy distribution (SED) in radio through IR (see, e.g., Markoff et al 2001;Maitra et al 2009a;Vila & Romero 2010), correlation between fluxes (see, e.g., Gallo et al 2003;Russell et al 2010), and scaling relations connecting radio and X-ray luminosities with the black hole mass (Merloni et al 2003;Falcke et al 2004;Gültekin et al 2009). …”