PP-waves from BPS supergravity monopoles

TL;DR

This paper explores the Penrose limit of BPS supergravity monopoles, revealing supersymmetric pp-wave solutions with enhanced supersymmetry and the necessity of abelianization via gauge coupling rescaling.

Contribution

It introduces the analysis of Penrose limits of non-abelian BPS monopoles, showing supersymmetry enhancement and the embedding in higher dimensions.

Findings

Rescaling gauge coupling to zero yields abelian pp-waves.

Supersymmetry is enhanced in the Penrose limit.

Embedding of solutions in 10-dimensional supergravity is discussed.

Abstract

We discuss the Penrose limit of the Chamseddine-Volkov BPS selfgravitating monopole in four dimensional N=4 supergravity theory with non-abelian gauge multiplets. We analyze the properties of the resulting supersymmetric pp-wave solutions when various Penrose limits are considered. Apart from the usual rescaling of coordinates and fields we find that a rescaling of the gauge coupling constant to zero is required, rendering the theory abelian. We also study the Killing spinor equations showing an enhancement of the supersymmetries preserved by the solutions and discuss the embedding of the pp-wave solution in $d=10$ dimensions.