3D simulations of the accretion process in Kerr space-time with arbitrary value of the spin parameter

TL;DR

This paper uses 3D general relativistic hydrodynamic simulations to study accretion in Kerr space-time, revealing equatorial outflows at high spin parameters, which could help distinguish black holes from super-spinars.

Contribution

The study extends previous 2.5D simulations to full 3D, confirming equatorial outflows and analyzing their dependence on the spin parameter and object radius.

Findings

Equatorial outflows form for high spin parameters.

Outflow onset depends mainly on the compact object radius.

Outflows are unlikely around black holes with |a_*| ≤ 1.

Abstract

We present the results of three-dimensional general relativistic hydrodynamic simulations of adiabatic and spherically symmetric accretion in Kerr space-time. We consider compact objects with spin parameter $|a_*| \le 1$ (black holes) and with $|a_*| > 1$ (super-spinars). Our full three-dimensional simulations confirm the formation of equatorial outflows for high values of $|a_*|$, as found in our previous work in 2.5 dimensions. We show that the critical value of $|a_*|$ determining the onset of powerful outflows depends mainly on the radius of the compact object. The phenomenon of equatorial outflows can hardly occur around a black hole and may thus be used to test the bound $|a_*| \le 1$ for astrophysical black hole candidates.