Junction conditions for composite matter in higher dimensions

Abstract

We derive the junction conditions for a general higher dimensional spherically symmetric radiating star across a comoving surface with an electromagnetic field. The charged composite interior consists of barotropic matter, a null dust and a null string fluid. The higher dimensional generalised Vaidya geometry describes the exterior radiating atmosphere of the charged composite star. We show at the stellar surface that the pressure is determined by the interior heat flux, anisotropy, null string density, charge distribution and the exterior null string density. The charge distribution affects the stellar pressure in general; the higher dimensional charged Vaidya spacetime is special and does not exhibit this feature. The number of dimensions appears explicitly in the surface pressure showing that the dimensions affect the gravitational dynamics. All previous treatments, for matter which is neutral or charged, emerge as special cases in our treatment.