Erlangen 2026 – scientific programme
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GR: Fachverband Gravitation, Relativistische Astrophysik und Kosmologie
GR 11: Numerical Relativity II
GR 11.2: Talk
Thursday, March 19, 2026, 11:30–11:45, KH 01.016
A novel approach for the systematic study of long-lived merger remnants with neutrino radiation — •Marie Cassing1, Luciano Rezzolla1,2,3, Carlo Musolino1, Konrad Topolski1, Harry Ho-Yin Ng1, and Keneth Miler1 — 1Goethe University Frankfurt, Frankfurt am Main, Germany — 2CERN, Theoretical Physics Department, Geneva, Switzerland — 3School of Mathematics, Trinity College, Dublin, Ireland
We introduce a novel hybrid framework for simulating binary neutron star mergers (BNS) with neutrino radiation, developed to explore the long-term evolution of postmerger remnants. The approach combines the strengths of the general-relativistic magnetohydrodynamics (GRMHD) code FIL for modeling the inspiral and merger phase with the advanced code BHAC+, which takes over in the postmerger phase. In BHAC+, we implement an M1 two-moment neutrino transport scheme and solve the stiff source terms with an implicit-explicit (IMEX) time integration strategy. This enables robust simulations of neutrino matter coupling over long timescales. Our primary aim is to study neutrino-driven winds, changes in remnant structure, and their potential to influence jet launching in scenarios involving long-lived neutron stars or delayed collapse to a black hole. We present results of M1 test problems and physical setups validating our implementation and outline the potential of this hybrid approach to systematically explore ejecta properties and electromagnetic counterparts in BNS mergers.
Keywords: Binary neutron star merger; Neutrinos; GRMHD; radiation transport