On the branes behind scale-separated AdS$_{3}$ flux vacua

Abstract

We investigate the brane origin of supersymmetric and scale-separated AdS$_3$ flux vacua arising in a class of type IIB orientifold reductions with G$_2$-structure. First, using the effective three-dimensional supergravity together with explicit uplift formulae, we trace back the $F_{(7)}$ and $F_{(3)}$ fluxes responsible for scale separation and identify the type IIB background that is probed by the corresponding D1- and D5-branes. Second, by restoring such D1- and D5-branes, we obtain a type IIB solution that interpolates between the previous background in the asymptotic region and the scale-separated AdS$_3$ flux vacua in the near-horizon region. Third, by working directly in ten dimensions, we construct a codimension-one D1-D5-KK5 intersection whose near-horizon region realises the scale-separated AdS$_3$ flux vacua. Our results provide a higher-dimensional interpretation of these flux vacua in terms of (smeared) brane configurations.