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

TL;DR

This paper models the appearance of black hole environments using relativistic radiation transport simulations, helping interpret VLBI/EHT observations of AGN discs, winds, and jets, and assessing how different parameters influence observable features.

Contribution

It introduces self-consistent GR-MHD simulations with resistivity and ray-tracing to predict observable signatures of SMBHs, including disc, wind, and jet features, under various conditions.

Findings

Reproduced EHT-like ring features with M87 parameters.

Identified how black hole properties affect observable structures.

Suggested other SMBHs may show winds and jets depending on parameters.

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.