On the impact of compact binary merger ejecta opacity on Kilonova transient signals

Abstract

Returns of gravitational wave astronomy will largely benefit from the detection and identification of electromagnetic (EM) signatures to gravitationalwave sources. Kilonovae (KNe) are promising EM counterparts to compact binary mergers, offering to astronomers and nuclear astrophysicists a unique window to advance knowledge on the heavy-element nucleosynthesis and mergerdriven mass ejection. However, extremely heterogeneous post-merging ejecta composition of both light- and heavy-r process nuclei, implies strong effects on the KNe light-curve identification due to the varying opacity of the system. Hence, large uncertainties on the r-process final abundance via spectroscopic analysis of KNe signals are still present, hardly fixed by theoretical models. Here we will present some peculiar features of KNe studies, focusing on the opacity issue, from the atomic and plasma physics perspectives. In this view, efforts have been made recently at INFN-LNS, trying to put constraints on plasma opacity of interest for early-stage KNe emission. We will present the experimental progress on the problem, including instruments and methods which could open an interdisciplinary approach to tackle astrophysical problems in laboratory plasmas.