Scalar absorption by spinning D3-branes

TL;DR

This paper investigates how scalar fields are absorbed by spinning D3-branes, revealing universal behaviors in absorption coefficients across various supergravity backgrounds and including both extremal and non-extremal cases.

Contribution

It provides a detailed analysis of scalar absorption by multi-center spinning D3-branes, uncovering universal patterns and extending understanding to non-extremal configurations.

Findings

Absorption coefficients show universal behavior related to angular momentum and temperature.

Resonances occur in spherically symmetric D-brane distributions, with similar patterns when excluding the enclosed region.

Non-extremal D-branes exhibit absorption features akin to extremal cases, at half the Hawking temperature.

Abstract

We discuss absorption of scalars by a distribution of spinning D3-branes. The D3-branes are multi-center solutions of supergravity theory. We solve the wave equation in various cases of supergravity backgrounds in which the equation becomes separable. We show that the absorption coefficients exhibit a universal behavior as functions of the angular momentum quantum number and the Hawking temperature. This behavior is similar to the form of the gray-body factors one encounters in scattering by black-holes. Our discussion includes the problematic case of spherically symmetric distributions of D-branes, where resonances arise. We obtain the same universal form for the absorption coefficients, if the region enclosed by the D-branes is excluded from physical considerations. Non-extremal D-branes are also discussed. The results are similar to the extremal cases, albeit at half the Hawking temperature. We speculate that new degrees of freedom enter as one moves away from extremality.