General relativistic radiation transport: implications for VLBI/EHT observations of AGN discs, winds, and jets

Abstract

In 2019, the Event Horizon Telescope Collaboration (EHTC) has published the first image of a supermassive black hole (SMBH) obtained via the Very Large Baseline Interferometry (VLBI) technique. In the future, it is expected that additional and more sensitive VLBI observations will be pursued for other nearby Active Galactic Nuclei (AGN), and it is therefore important to understand which possible features can be expected in such images. In this paper, we post-process General Relativistic Magneto-Hydrodynamical (GR-MHD) simulations which include resistivity, thus providing a self-consistent jet formation model, including resistive mass loading of a wind launched from a disc in Keplerian rotation. The ray-tracing is done using the General Relativistic Ray-Tracing code GRTRANS assuming synchrotron emission. We study the appearance of the black hole environment including the accretion disc, winds and jets under a large range of condition, varying black hole mass, accretion rate, spin, inclination angle, disc parameters and observed frequency. When we adopt M87-like parameters, we show that we can reproduce a ring-like feature (similar as observed by the EHT) for some of our simulations. The latter suggests that such Keplerian disc models thus could be consistent with the observed results. Depending on their masses, accretion rates, spin and the sensitivity of the observation, we note that other SMBHs may show additional features like winds and jets in the observations.

Truncated accretion discs in black hole X-ray binaries: dynamics and variability signatures

“…As the wind leaves our area of interest (r 60), total emission drops drastically (t = 9000). Our observation of an extended ring structure nicely fits with the GR-MHD ray-traced emission maps by Bandyopadhyay et al (2021), who investigated how the structural components of a BH jet source -the BH, the disc, the spine jet, and the disc wind -may be disentangled by their radiative imprints.…”

“…Note that the spectral properties of an accretion disc depend on the mass of the black hole, accretion rate, line of sight angle, non-thermal particles, R l , R h parameters, etc. (e.g., Bandyopadhyay et al 2021;Mizuno et al 2021;Fromm et al 2021). For this study, we do not intend to do parametric studies.…”