Tidal heating in a Riemann-Cartan spacetime

TL;DR

This paper explores how torsion in a Riemann-Cartan spacetime affects black hole tidal heating, revealing modifications to Hawking radiation and gravitational energy loss.

Contribution

It extends the Hawking-Hartle tidal heating formula to include torsion effects, showing new phenomenological implications for black hole physics.

Findings

Torsion introduces additional terms in tidal heating calculations.

Modifications affect the Bondi mass and gravitational radiation.

Hawking radiation spectrum is altered by torsion effects.

Abstract

We consider possible perturbations of the black hole event horizon induced by matter with spin, extending the derivation of the Hawking-Hartle formula (tidal heating) in the presence of torsion. When specialised to theories with a non-vanishing (pseudo-)traceless component of the (con)torsion tensor, we remarkably find that the tidal heating phenomenon gets modified by additional torsion-dependent terms, in agreement with previous investigations based on Jacobson's spacetime thermodynamics approach. These results lead to relevant phenomenological and theoretical consequences: modifications in the Hawking-Hartle term change the Bondi mass associated with the gravitational radiation observed at infinity, and modify the Hawking radiation spectrum of evaporating black holes.