Physical conditions for the r-process

Recent works show that the r-process can proceed by competition between neutron capture and β-decay in low temperature environments (< 5 × 108 K; cold r-process) where photo-disintegration plays no role. This is in contrast to the traditional picture of the r-process in high temperature environments (∼ 1 × 109 K; hot r-process) where the (n, γ)-(γ, n) equilibrium holds. In this study, we explore nucleosynthesis calculations based on a site-independent model to elucidate the physical conditions leading to cold and hot r-processes.