Hawking Radiation from Small Black Holes at Strong Coupling and Large N

TL;DR

This paper investigates the holographic dual of Hawking radiation from small black holes in strongly coupled large N gauge theories, revealing features similar to weakly-coupled Hawking radiation through stress tensor analysis.

Contribution

It computes the holographic stress tensor for a black string solution, demonstrating key features of the Unruh state in strongly coupled gauge theories at large N and strong coupling.

Findings

Stress tensor exhibits negative energy density near the horizon.

Positive energy density observed at infinity.

No flux terms at leading order in N, consistent with black droplet phase.

Abstract

In a previous work an approximate static metric was found of a test black string that stretches from the boundary to the horizon of the planar Schwarzschild-AdS_5 geometry. This is the gravity dual of the Unruh state for \mathcal{N}=4, SU(N) super Yang-Mills theory on a 4-dimensional Schwarzschild background, at large N and large 'tHooft coupling. We compute the holographic stress tensor of the gravitational solution and it turns out to possess many essential features of the Unruh state for weakly-coupled Hawking radiation, such as the appearance of a negative energy density near the black hole horizon and a positive energy density at infinity. It also confirms recent results that at leading order in N, the expectation value of the stress tensor in the Unruh state is finite on both the future and past horizons, and that at this order there are no flux terms as is expected in the black droplet phase.