Novel mechanism for vorticity generation in black-hole accretion disks

TL;DR

This paper investigates how vorticity is generated in black-hole accretion disks within relativistic and modified gravity frameworks, revealing that Kerr black holes produce more vorticity than Schwarzschild ones, especially near the isco.

Contribution

It introduces a new relativistic vorticity generation mechanism in accretion disks, comparing effects in GR and modified gravity, highlighting the dominance of relativistic drive near the isco.

Findings

Kerr geometry enhances vorticity generation compared to Schwarzschild.

Relativistic drive peaks near the innermost stable circular orbit.

Baroclinic drive dominates at larger disk radii.

Abstract

Vorticity generation in accretion disks around Schwarzschild and Kerr black holes is investigated in the context of magnetofluid dynamics derived for both General Relativity (GR), and modified gravity formulations. In both cases, the Kerr geometry leads to a "stronger" generation of vorticity than its Schwarzschild counterpart. Of the two principal sources, the relativistic drive peaks near the innermost stable circular orbit (isco), whereas the baroclinic drive dominates at larger distances. Consequences of this new relativistic vorticity source are discussed in several astrophysical settings.