Erlangen 2026 – scientific programme

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GR: Fachverband Gravitation, Relativistische Astrophysik und Kosmologie

GR 12: Relativistic Astrophysics III / Gravitational waves III

GR 12.2: Talk

Thursday, March 19, 2026, 14:00–14:15, KH 01.016

Impact of in-situ nuclear networks and atomic opacities on neutron star merger ejecta dynamics, nucleosynthesis, and kilonovae — •Fabio Magistrelli — TPI, FSU Jena

Binary neutron star merger (BNSM) ejecta are key sites of rapid neutron-capture (r-process) nucleosynthesis and power kilonovae through the radioactive decay of freshly synthesized nuclei. I will present a systematic study of how nuclear burning, particle thermalization, and atomic opacity treatments impact the nucleosynthesis and electromagnetic emission from BNSM ejecta, starting from ejecta profiles extracted from ab-initio numerical-relativity simulations and evolved up to ∼30 days with radiation-hydrodynamics calculations with in-situ nuclear reaction networks (NN). I will compare simplified and composition-dependent thermalization schemes, as well as gray opacity models and frequency-dependent, atomic-physics-based opacities. Finally, I will discuss how NN coupling and detailed thermalization and opacity treatments significantly modify the temperature evolution of the ejecta, the structure of the r-process peaks, and the brightness and color evolution of the associated kilonova for realistic ejecta profiles.

Keywords: compact binary mergers; nucleosynthesis; kilonovae; atomic opacities