ELEMENTS will achieve a comprehensive understanding of the nuclear EOS relevant to NSs based on QCD calculations. This includes constraints from ab-initio calculations at nuclear densities and beyond (Braun, Schwenk), including degrees of freedom beyond nucleons and pions (Elfner), constraints from QCD (Cuteri, Moore, Philipsen, Rischke) and modelling of QCD at intermediate densities, as well as constraints from short-range correlations in nuclear experiments (Aumann, Obertelli) and HICs (Galatyuk, Stroth). The novel understanding of the properties of the EOS will complement the astronomical and GW measurements of NS radii (Rezzolla, Schwenk).
ELEMENTS will study the dynamics of binary neutron-star (BNS) merger events using the most advanced numerical simulations in general relativity to obtain accurate predictions of the expected GW signal and on its EM counterpart (Arcones, Bauswein, Martínez-Pinedo, Rezzolla). Significant progress will be achieved in determining the impact of general-relativistic (GR) magnetohydrodynamic (MHD) turbulences, MHD instabilities, and magnetic-field amplification on the remnant produced by merging NSs. We will investigate the impact of phase transitions on the dynamics of BNS mergers (Bauswein, Rezzolla) and their GW signal, extending and improving the very successful work done so far. In addition, we will also use BNS mergers as a powerful tool to explore violations of theory of General Relativity and find signatures of alternative theories of gravity (Sagunski). ELEMENTS will develop novel formulations in relativistic dissipative hydrodynamics and MHD and apply them to both HICs and BNS mergers (Elfner, Rezzolla, Rischke). Furthermore, it will extend fluctuation measurements by including the reconstruction of light nuclei and the detection of neutrons by combining detection capabilities of HADES and R3B with pilot experiments performed within the FAIR Phase-0 infrastructure (Aumann, Galatyuk, Obertelli, Stroth).
ELEMENTS will provide new information on neutron-capture rates on neutron-rich nuclei (Litvinov, Reifarth) and on properties of transuranium actinides that provide constraints for the fission cycle of the r-process of nucleosynthesis in BNS mergers (Arnold, Block, Galatyuk, Martínez-Pinedo, Pietralla). Under these extreme conditions, the involved nuclides are highly ionized, which can dramatically change their decay characteristics from those known in neutral atoms. ELEMENTS will interconnect the individual storage-ring complexes of GSI and FAIR to boost experimental capabilities for corresponding precision experiments (Block, Litvinov, Reifarth, Stöhlker). Penning-trap mass spectrometry will provide nuclear masses with high accuracy. The high resolving power will be used to prepare pure data samples selecting specific nuclear isomeric states for decay spectroscopy (Arcones, Arnold, Block, Pietralla). This work will open new routes to determine exotic decay branches.
ELEMENTS will compare the abundances of heavy elements and the kilonova light-curvespredicted by numerical simulations (Arcones, Martínez-Pinedo) with the astronomical observations to constrain and understand the impact of the microphysics on the simulations and the nucleosynthesis (Bauswein, Rezzolla). Precision studies, to be performed for bare and H-like uranium at the GSI/FAIR storage rings, will provide detailed information about the relativistic and especially magnetic-interaction effects on the electron-photon coupling (Schippers, Stöhlker). Astronomical observation of the composition of the debris produced by BNS mergers will reveal the emission and absorption features from heavy ions. Furthermore, accurate recombination-rate coefficients of heavy ions will be measured at the FAIR ion-storage rings (Bai, Litvinov, Reifarth, Schippers, Stöhlker) for a reliable determination of elemental abundances from the astronomical observations.