Jet Signatures in the Spectra of Accreting Black Holes

TL;DR

This paper investigates jet signatures in accreting black holes, revealing characteristic spectral features and variability patterns that help distinguish jet emission from other sources in X-ray binaries.

Contribution

It introduces detailed simulations of jet spectra and variability, highlighting specific high-energy signatures and the impact of magnetic reconnection events.

Findings

Detection of a gamma-ray peak above 10^22 Hz

Identification of spectral breaks in optical/UV range

Correlation between jet activity and gamma-ray to X-ray luminosity ratio

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 gamma-ray peak above ~10^22 Hz, (ii) a break in the optical/UV spectrum, with a change in luminosity from L ~ nu^0 to L ~ nu, followed by another break at higher frequencies where the spectrum roughly returns to L ~ nu^0, 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 gamma-rays to X-rays changes from L_gamma / L_X > 1 in the BZ jet to L_gamma / L_X < 1 during the launching of the transient plasmoid.