Electromagnetic dipole transitions in nuclei at finite temperature

Describing the properties of highly excited or hot nuclei remains as a major challenge both for nuclear theory and experiment. We developed self-consistent finite-temperature relativistic quasiparticle random phase approximation (FT-RQRPA) using the relativistic energy density functional with point-coupling interaction to study temperature effects on electromagnetic transitions. We investigate electric dipole (E1) and magnetic dipole (M1) transitions in calcium and tin nuclei at temperatures from T = 0 to 2 MeV. Our results show that both E1 and M1 responses change with temperature, with E1 strength undergoing slight modifications and new low-energy peaks emerging due to thermal blocking. The M1 strength shifts significantly to lower energies, and new M1 states emerge that are forbidden at zero temperature. These findings can be important for modeling gamma strength functions in astrophysical nuclear reactions.