Penrose limits in massive type-IIA AdS$_3$ background

Abstract

In this paper we consider the non-Abelian T-dual geometry of the type IIB supergravity theory on AdS 3 × S 3 × T 4 background along a convenient SU(2) subgroup of the SO(4) R-symmetry. We examine various null geodesics of the resulting massive type IIA supergravity theory and investigate the Penrose limits along these geodesics. We find that one of the resulting backgrounds admits pp-wave geometry in the neighbourhood of a suitable null geodesic. We carry out the supersymmetry analysis of the resulting pp-wave geometry and observe that it preserves sixteen supercharges. Further we comment on the possible gauge theory dual of the resulting pp-wave background.