Transition strength functions: from stable nuclei towards hot stellar environments

par Nils Paar (University of Zagreb Faculty of Science, Zagreb, Croatia)

jeudi 15 mai 2025, 11:00 → 13:00 Europe/Paris

Salle Pistache (Batiment 27)

This talk addresses the evolution of nuclear excitation modes from stable toward neutron-rich nuclei, including nuclei in hot stellar environments, within the relativistic energy density functional (EDF) framework. Collective excitations, such as electric dipole and isoscalar giant monopole resonances, are essential tools for constraining key EDF parameters like symmetry energy and nuclear incompressibility. Their isotopic dependence offers insight into neutron-rich systems and the nuclear equation of state. Using a self-consistent relativistic quasiparticle random phase approximation (RQRPA), the structure of electric and magnetic dipole strength has been investitaged across closed- and open-shell nuclei. The model is extended to finite temperature (FT-RQRPA) to explore how thermal effects influence excitation modes. At increased temperatures, nuclear properties undergo significant changes, including modifications to shell structure, transition strengths, and even the position of the drip lines. Thermal unblocking of single particle states leads to the appearance of low-energy electric and magnetic dipole transitions not present at zero temperature. These thermal effects strongly influence the gamma-ray strength function, which plays a key role in astrophysical reaction rates.