Göttingen 2025 – scientific programme
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GR: Fachverband Gravitation und Relativitätstheorie
GR 2: Relastro I
GR 2.3: Talk
Tuesday, April 1, 2025, 14:35–14:55, ZHG008
Realistic models of general-relativistic differentially rotating stars — •Marie Cassing1 and Luciano Rezzolla1,2,3 — 1Institute for Theoretical Physics, Frankfurt am Main, Germany — 2Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany — 3School of Mathematics, Trinity College, Dublin, Ireland
General-relativistic equilibria of differentially rotating stars are expected in a number of astrophysical scenarios, from core-collapse supernovae to the remnant of binary neutron-star mergers. The latter, in particular, have been the subject of extensive studies where they were modelled with a variety of laws of differential rotation. Starting from accurate and fully general-relativistic simulations of binary neutron-star mergers with various equations of state, we establish the time when the merger remnant has reached a quasi-stationary equilibrium and extract in this way realistic profiles of differential rotation. This allows us to explore how well traditional laws reproduce such differential-rotation properties and to derive new laws of differential rotation that better match the numerical data. In this way, we have obtained a novel and somewhat surprising result: the stability line computed from the turning-point criterion can have a slope that is not necessarily negative with respect to the central rest-mass density, as previously found with traditional differential-rotation laws. For stellar models reproducing well the properties of the merger remnants, the slope is actually positive, thus reflecting remnants with angular momentum at large distances from the rotation axis, and hence with cores having higher central rest-mass densities and slower rotation rates.
Keywords: neutron-stars; equation of state; stars: rotation; methods: numerical; binary neutron-star merger