Thermal quasiparticle random-phase approximation calculations of stellar electron capture rates with the Skyrme effective interaction

Abstract

A microscopic thermodynamically consistent approach is applied to compute electron capture (EC) rates and cross sections on nuclei in hot stellar environments. The cross section calculations are based on the Donnelly-Walecka multipole expansion method for treatment of semi-leptonic processes in nuclei. To take into account thermal effects, we express the electron capture cross section in terms of temperature- and momentum-dependent spectral functions for respective multipole charge-changing operators. The spectral functions are computed by employing the self-consistent thermal quasiparticle RPA (TQRPA) with the Skyrme effective interaction. Three different Skyrme parametrizations (SkM${}^{\ast }$, SGII and SLy4) are used to investigate thermal effects on EC for ${}^{56}$Fe and ${}^{78}$Ni. For ${}^{56}$Fe, the impact of thermally unblocked GT${}_{+}$ transitions on EC is discussed and the results are compared with those from shell-model calculations. In particular, it is shown that for some temperature and density regimes the TQRPA rates exceed the shell-model rates due to violation of the Brink-Axel hypothesis within the TQRPA. For neutron-rich ${}^{78}$Ni the full momentum-dependence of multipole transition operators is considered and it is found that not only thermally unblocked allowed $1^{+}$ transitions but also thermally unblocked first-forbidden $1^{-}$ and $2^{-}$ transitions favour EC.

References in corpus (6)

• Theory of Core-Collapse Supernovae
• Stellar electron-capture rates calculated with the finite-temperature relativistic random-phase approximation
• The Gamow-Teller response within Skyrme random-phase approximation plus particle-vibration coupling
• Spin-isospin nuclear response using the existing microscopic Skyrme functionals
• Modification of the Brink-Axel Hypothesis for High Temperature Nuclear Weak Interactions
• Nuclear Weak Rates and Detailed Balance in Stellar Conditions

Cited by in corpus (9)

• Electron capture in stars
• Unblocking of stellar electron capture for neutron-rich $N=50$ nuclei at finite temperature
• Impact of complex many-body correlations on electron capture in thermally excited nuclei around ${}^{78}$Ni
• Stellar electron capture rates based on finite temperature relativistic quasiparticle random-phase approximation
• Nuclear Weak Rates and Nuclear Weak Processes in Stars
• Finite-temperature electron-capture rates for neutron-rich nuclei around N=50 and effects on core-collapse supernovae simulations
• A modified Brink-Axel hypothesis for astrophysical Gamow-Teller transitions
• Neutrinos from pre-supernova in the framework of TQRPA method
• Validity of Brink Axel Hypothesis for calculations of allowed stellar weak rates of heavy nuclei