# Marc Mars: Existence and uniqueness of rigidly rotating stars in second order perturbation theory

**Time: **
Tue 2019-10-08 10.00 - 11.00

**Location: **
Seminar Hall Kuskvillan, Institut Mittag-Leffler

**Lecturer: **
Marc Mars, University of Salamanca

### Abstract

The Hartle-Thorne model describes slowly, rigidly rotating stars in the strong field regime by using perturbation theory up to second order. The model involves a number of hypotheses, some explicit and some implicit, on the structure and regularity of the perturbation tensors. In this talk I present work in collaboration with Reina and Vera where slowly, rigidly rotating fluid balls are analyzed consistently in second order perturbation theory by imposing only basic differentiability requirements. We prove in particular that, at this level of approximation, the spacetime is fully determined by two parameters, namely the central pressure and the rotation parameter of the fluid.