Hawking radiation from dilatonic black holes via anomalies

TL;DR

This paper extends the anomaly cancellation method to derive Hawking radiation from various dilatonic black holes, including rotating and extremal cases, confirming the universality of the anomaly approach.

Contribution

It applies the gravitational anomaly method to a broader class of black holes, including dilatonic, Kaluza-Klein, and Kerr-Sen types, and discusses properties near extremality.

Findings

Hawking radiation flux matches blackbody radiation at Hawking temperature.

Method successfully applies to static, rotating, and extremal dilatonic black holes.

Supports the universality of anomaly-based Hawking radiation derivation.

Abstract

Recently, Hawking radiation from a Schwarzschild-type black hole via gravitational anomaly at the horizon has been derived by Robinson and Wilczek. Their result shows that, in order to demand general coordinate covariance at the quantum level to hold in the effective theory, the flux of the energy momentum tensor required to cancel gravitational anomaly at the horizon of the black hole, is exactly equal to that of (1+1)-dimensional blackbody radiation at the Hawking temperature. In this paper, we attempt to apply the analysis to derive Hawking radiation from the event horizons of static, spherically symmetric dilatonic black holes with arbitrarily coupling constant $\alpha$, and that from the rotating Kaluza-Klein $(\alpha = \sqrt{3})$ as well as the Kerr-Sen ($\alpha = 1$) black holes via an anomalous point of view. Our results support Robinson-Wilczek's opinion. In addition, the properties of the obtained physical quantities near the extreme limit are qualitatively discussed.