Electric and magnetic $γ$-ray strength functions at finite-temperature

Abstract

The $γ$-ray strength function ($γ$SF) is essential for understanding the electromagnetic response in atomic nuclei and modeling astrophysical neutron capture rates. We introduced a microscopic description of both electric dipole (E1) and magnetic dipole (M1) $γ$SFs that includes finite-temperature effects within relativistic density functional theory. The temperature dependence of the total electromagnetic $γ$SFs shows significant modification in the low-energy region due to thermal unblocking effects, essential for agreement with recent particle-$γ$ coincidence data from the Oslo method. An investigation of the electric and magnetic contributions to the total $γ$SF in hot nuclei indicates that the M1 mode becomes more prominent in the low-energy region, different than what is known at zero temperature. This microscopic approach offers new insights into the interplay between E1 and M1 $γ$SFs at finite-temperature, and opens new perspectives for future studies of $(n,γ)$ reactions and nucleosynthesis in hot stellar environments.