A Physical Link Between Jet Formation and Hot Plasma in Active Galactic Nuclei

Abstract

Recent observations suggest that in black hole X-ray binaries jet/outflow formation is related to the hot plasma in the vicinity of the black hole, either in the form of an advection-dominated accretion flow at low accretion rates or in a disk corona at high accretion rates. We test the viability of this scenario for supermassive black holes using two samples of active galactic nuclei distinguished by the presence (radio-strong) and absence (radio-weak) of well-collimated, relativistic jets. Each is centered on a narrow range of black hole mass but spans a very broad range of Eddington ratios, effectively simulating, in a statistical manner, the behavior of a single black hole evolving across a wide spread in accretion states. Unlike the relationship between the radio and optical luminosity, which shows an abruptly break between high-and low-luminosity sources at an Eddington ratio of ∼ 1%, the radio emission-a measure of the jet power-varies continuously with the hard X-ray (2-10 keV) luminosity, roughly as L R ∝ L 0.6−0.75 X . This relation, which holds for both radio-weak and radio-strong active galaxies, is similar to the one seen in X-ray binaries. Jet/outflow formation appears to be closely linked to the conditions that give rise to the hot, optically thin coronal emission associated with accretion flows, both in the regime of low and high accretion rates.

On the Thermal Line Emission From the Outflows in Ultraluminous X-Ray Sources

“…A similar feature has been found in active galactic nuclei (AGNs; Wu et al 2013). These imply that the jet formation may probably be related to the hot coronae above the thin disks (Merloni & Fabian 2002;Cao 2004;Zdziarski et al 2011;Wu et al 2013). The calculations of magnetically accelerated outflows show that hot gas (probably in the corona) is necessary for launching an outflow from the radiation-pressure-dominated accretion disk (Cao 2014).…”

“…A radio-X-ray correlation in Cygnus X-1 is found to extend to the high/soft state only if its hard X-ray emission is considered (after subtracting the blackbody component emitted from the thin disk; Zdziarski et al 2011). A similar feature has been found in active galactic nuclei (AGNs; Wu et al 2013). These imply that the jet formation may probably be related to the hot coronae above the thin disks (Merloni & Fabian 2002;Cao 2004;Zdziarski et al 2011;Wu et al 2013).…”

On the efficiency of jet production in FR II radio galaxies and quasars

“…Cao 2004;Wu et al 2013). However, in order to produce at λ Edd > 0.01 jets with Pj/L d approaching unity, as is observed for many objects, requires magnetic fluxes in the central regions too large to be supported by disc coronas.…”

The Outflows Accelerated by the Magnetic Fields and Radiation Force of Accretion Disks

“…Therefore, it is difficult for the outflows to be driven from the photospheres of the radiation-dominated disks. This implies that hot gas (probably in the corona) is necessary for launching an outflow from the radiation-pressure-dominated disk, which provides a natural explanation for the observational evidence that relativistic jets are related to hot plasma in some X-ray binaries and AGNs (Zdziarski et al 2011;Wu et al 2013).…”