Musarat Abbas, Jameel‐Un Nabi, Arslan Mehmood
Abstract The simulation of the observed properties of type I X-ray bursts, also known as superbursts, poses challenges once Cooper pair neutrino emission from the crust of the neutron star are included. Further, additional heating of the accumulating fuel layer is required. The emission of γ -rays caused by electron captures to excited states in astrophysical environments is a major source of heat loss competing with that carried away by weak-interaction neutrinos. γ -heating significantly affect the presupernova evolution of massive stars and the calculation of the thermal structure in the crust and core of superbursts. This energy deposition enhances entropy production and promotes convection at this stage of stellar evolution. Effective γ -heating rates reduce the ignition depth of superbursts. A recent investigation ranked the leading electron capturing nuclei as the cause for significant changes in the lepton-to-baryon fraction ( ) of the stellar matter after silicon core burning. We investigate γ -heating rates from the excited states of the top 100 electron capture and positron decay nuclei identified in recently published ranking lists. Each nucleus was analyzed using four different empirical pairing gaps and three distinct sets of nuclear deformation parameters to assess the effect of γ -heating rates. We report our calculations for the temperature range of 1−10 GK and density range of − g/cm . The calculated γ -heating rates changes up to a factor 26 (16) with changing deformation values (pairing gaps). Our findings may contribute to more realistic simulations of post-silicon burning phases of massive stars and superbursting neutron stars.