Microscopic Entropy of AdS$_3$ Black Holes Revisited

TL;DR

This paper revisits the microscopic understanding of AdS$_3$ black holes, proposing an entropy extremization principle and interpreting supersymmetric black holes as constrained ensembles of BPS microstates, enhancing the understanding of their charge constraints.

Contribution

It introduces an entropy extremization principle for AdS$_3$ black holes and interprets BPS states as constrained microstate ensembles, clarifying charge constraints.

Findings

Formulated an entropy extremization principle for AdS$_3$ black holes.

Provided a microscopic interpretation of charge constraints in BPS black holes.

Developed thermodynamics and attractor mechanism for nearBPS AdS$_3$ black holes.

Abstract

We revisit the microscopic description of AdS$_3$ black holes in light of recent progress on their higher dimensional analogues. The grand canonical partition function that follows from the AdS$_3$/CFT$_2$ correspondence describes BPS and nearBPS black hole thermodynamics. We formulate an entropy extremization principle that accounts for both the black hole entropy and a constraint on its charges, in close analogy with asymptotically AdS black holes in higher dimensions. We are led to interpret supersymmetric black holes as ensembles of BPS microstates satisfying a charge constraint that is not respected by individual states. This interpretation provides a microscopic understanding of the hitherto mysterious charge constraints satisfied by all BPS black holes in AdS. We also develop thermodynamics and a nAttractor mechanism of AdS$_3$ black holes in the nearBPS regime.