Weak-interaction mediated rates on iron isotopes for presupernova evolution of massive stars

Abstract

During the presupernova evolution of massive stars, the isotopes of iron, ${}^{54,55,56}$Fe, are advocated to play a key role inside the cores primarily decreasing the electron-to-baryon ratio ($Y_e$) mainly via electron capture processes thereby reducing the pressure support. Electron decay and positron capture on ${}^{55}$Fe, on the other hand, also has a consequential role in increasing the lepton ratio during the silicon burning phases of massive stars. The neutrinos and antineutrinos produced, as a result of these weak-interaction reactions, are transparent to the stellar matter and assist in cooling the core thereby reducing the entropy. The structure of the presupernova star is altered both by the changes in $Y_e$ and the entropy of the core material. The aim of this paper is to report the improved microscopic calculation of Gamow-Teller (GT${}_{\pm }$) strength distributions of these key isotopes of iron using the pn-QRPA theory. The main improvement comes from the incorporation of experimental deformation values for these nuclei. Additionally six different weak-interaction rates, namely electron & positron capture, electron & positron decay, and, neutrino & antineutrino cooling rates, were also calculated in presupernova matter. The calculated electron capture and neutrino cooling rates due to isotopes of iron are in good agreement with the large-scale shell model (LSSM) results. The calculated beta decay rates, however, are suppressed by three to five orders of magnitude.

11 pages, 4 figures, 4 tables

References in corpus (5)

• Gamow-Teller transitions and deformation in the proton-neutron random phase approximation
• Comparative study of Gamow-Teller strength distributions in the odd-odd nucleus 50V and its impact on electron capture rates in astrophysical environments
• Gamow-Teller transitions from 24Mg and its impact on the electron capture rates in the O + Ne + Mg cores of stars
• Neutrino energy loss rates and positron capture rates on ${}^{55}$Co for presupernova and supernova physics
• Stellar neutrino energy loss rates due to ${}^{24}$Mg suitable for O+Ne+Mg core simulations

Cited by in corpus (2)

• Neutrino and antineutrino energy loss rates in massive stars due to isotopes of titanium
• $\beta$-decay of key titanium isotopes in stellar environment