Imaging a Semi-Analytical Jet model Generated by 3D GRMHD Simulation

TL;DR

This paper uses 3D GRMHD simulations to generate and analyze images of a thin jet around a spinning black hole, revealing unique brightness features and frequency insensitivity across different accretion states.

Contribution

It introduces a semi-analytical jet imaging method based on simulation data, highlighting distinctive brightness patterns and their relation to jet regimes.

Findings

Brighter U-shaped lines appear near jet boundaries.

Jet images are largely insensitive to observation frequency.

Time-averaged images show minor differences between MAD and saturation regimes.

Abstract

Employing 3D GRMHD simulation, we study the images of a geometrically thin jet, whose emissions concentrate on its surface, for accretion system surrounding a central spinning BH. By introducing a strong magnetic field, we observe three phases of BH accretion evolution: (a) initially, both the accretion rate and the magnetic flux on the horizon gradually increase; (b) at an intermediate stage, the magnetic flux approximately reaches saturation, and a jet forms via the Blandford-Znajek (BZ) mechanism; (c) ultimately, the entire system achieves a dynamic equilibrium, and a magnetically arrested disk (MAD) forms. We carefully study the jet images during the saturation and MAD regimes at various frequencies and from different observational angles. We reveal the presence of U-shaped brighter lines near the jet surface boundaries, which can be attributed to the photons whose trajectories skim over the jet surface. The existence of these brighter lines is a unique feature of a geometrically thin jet. Moreover, we notice that the jet images are relatively insensitive to the observed frequencies of interest. Additionally, we observe that the time-averaged images for the highly oscillating MAD regime show only slight differences from those of the saturation regime.