Some considerations about NS5 and LST Hawking radiation

TL;DR

This paper compares Hawking radiation in NS5 and LST black hole models using semi-classical methods, revealing non-thermal behavior in NS5 due to energy conservation, while LST remains thermal.

Contribution

It demonstrates the application of complex path and gravitational anomaly methods to these models and clarifies the thermal properties related to energy dependence.

Findings

NS5 exhibits non-thermal Hawking radiation due to energy conservation.

LST maintains thermal radiation with energy-independent temperature.

Both methods agree on the temperature calculations for the models.

Abstract

We have studied the Hawking radiation corresponding to the NS5 and Little String Theory (LST) black hole models using two semi-classical methods: the complex path method and a gravitational anomaly. After summarizing some known concepts about the thermodynamics of these theories, we have computed the emission rates for the two black hole models. The temperature calculated from, e.g. the well-known surface gravity expression, is shown to be identical to that obtained from both the computation of the gravitational anomaly and the complex path method. Moreover, the two semi-classical methods show that NS5 exhibits non-thermal behavior that contrasts with the thermal behavior of LST. We remark that energy conservation is the key factor leading to a non-thermal profile for NS5. In contrast, LST keeps a thermal profile even when energy conservation is considered because temperature in this model does not depend on energy.