Black hole polarization and new entropy bounds

TL;DR

This paper derives a new entropy bound for charged black holes considering polarization effects and proposes a combined bound for charged rotating objects, advancing the understanding of black hole thermodynamics.

Contribution

It provides a derivation of Zaslavskii's optimized entropy bound through black hole polarization effects and introduces a unified bound for charged rotating objects.

Findings

Derived a tighter entropy bound for charged objects accreting black holes.

Proposed a combined entropy bound for charged rotating objects.

Showed the bound cannot be further tightened using global charges.

Abstract

Zaslavskii has suggested how to tighten Bekenstein's bound on entropy when the object is electrically charged. Recently Hod has provided a second tighter version of the bound applicable when the object is rotating. Here we derive Zaslavskii's optimized bound by considering the accretion of an ordinary charged object by a black hole. The force originating from the polarization of the black hole by a nearby charge is central to the derivation of the bound from the generalized second law. We also conjecture an entropy bound for charged rotating objects, a synthesis of Zaslavskii's and Hod's. On the basis of the no hair principle for black holes, we show that this last bound cannot be tightened further in a generic way by knowledge of ``global'' conserved charges, e.g., baryon number, which may be borne by the object.