Jet Signatures in the Spectra of Accreting Black Holes

Abstract

Jets are observed as radio emission in active galactic nuclei and during the low/hard state in X-ray binaries (XRBs), but their contribution at higher frequencies has been uncertain. We study the dynamics of jets in XRBs using the general-relativistic magnetohydrodynamic code HARM. We calculate the high-energy spectra and variability properties using a general-relativistic radiative transport code based on grmonty. We find the following signatures of jet emission: (i) a significant γ-ray peak above ∼10 22 Hz, (ii) a break in the optical/UV spectrum, with a change from L 0 n ñ n to L n ñ n , followed by another break at higher frequencies where the spectrum roughly returns to L 0 n ñ n , and (iii) a pronounced synchrotron peak near or below ∼10 14 Hz indicates that a significant fraction of any observed X-ray emission originates in the jet. We investigate the variability during a large-scale magnetic field inversion in which the Blandford-Znajek (BZ) jet is quenched and a new transient hot reconnecting plasmoid is launched by the reconnecting field. The ratio of the γ-rays to X-rays changes from L L 1 X > g in the BZ jet to L L 1 X < g during the launching of the transient plasmoid.

Magnetic reconnection and Blandford–Znajek process around rotating black holes

“…This can be associated with change of states in black hole X-ray binaries. Further continuing the same set of GRMHD simulations, O'Riordan, Pe'er & McKinney (2016) showed that for a population of thermal electrons, during launching of the transient plasmoid, when BZ jet is quenched, the ratio of gamma-ray luminosity to X-ray luminosity becomes less than 1 while in the case of the steady BZ jet it remains greater than 1. Beskin & Zheltoukhov (2013), using a force free analytical solution under the assumption of axisymmetric and stationary flow, could explain the profile of the angular velocity of the field lines which were obtained from the 3D GRMHD simulations of McKinney, Tchekhovskoy, Blandford (2012).…”

Effects of Spin on High-Energy Radiation From Accreting Black Holes

“…We give the velocity in units of the Keplerian speed = v r 1 K . The "thinnermadx" models are those considered here (where the number x gives the spin), while the "thickdisk7" and "nonmad" models are the MAD and SANE models considered in O' Riordan et al (2016 Figure 11 we show the effects of varying f¢ v for a black hole with a=0.9. The difference between the observed and comoving power is a factor of  2 .…”

“…100-122;Cadolle Bel et al 2006;Yuan et al 2007;Narayan & McClintock 2008;Niedźwiecki et al 2012Niedźwiecki et al , 2014Qiao & Liu 2015). However, it is also possible that a significant fraction of the X-ray emission originates in jets (e.g., Mirabel & Rodríguez 1994;Markoff et al 2001Markoff et al , 2003Markoff et al , 2005Markoff et al , 2015Falcke et al 2004;Bosch-Ramon et al 2006;Gupta et al 2006;Kaiser 2006;Kylafis et al 2008;Maitra et al 2009;Pe'er & Casella 2009;Pe'er & Markoff 2012;O' Riordan et al 2016).…”

Observational Signatures of Mass-loading in Jets Launched by Rotating Black Holes

“…Although the injected numerical density floors do not affect the dynamics, they can be artificially hot and so might affect the resulting spectra. In O' Riordan et al (2016aRiordan et al ( , 2016b, we considered the case where material from the central regions of the funnel does not contribute significantly to the observed spectrum. That is, we removed the floor material such that the middle of the funnel region was empty.…”

“…This "empty funnel" situation can also be achieved by simply removing floor material from the funnel during the radiative transport calculation. The material to remove can be chosen in a number of ways, for example, as cells in a large bipolar cone (Shcherbakov & McKinney 2013), cells considered artificially hot or dense relative to their neighbors (Chan et al 2015b), or cells with a large value of σ (O' Riordan et al 2016aRiordan et al , 2016b.…”