Screening Effects on Electron-Capture Rates and Type Ia Supernova Nucleosynthesis

Toshio Suzuki,Toshitaka Kajino,Michael A Famiano,A Baha Balantekin,Kanji Mori,Michio Honma,Motohiko Kusakabe,W Liu,X Tang,S Zeng,Y Wang,B Guo

doi:10.1051/epjconf/202226006004

Abstract

Nucleosynthesis of iron-group elements in Type Ia supernovae is studied for single-degenerate models with the use of electron-capture rates updated with the new shell-model Hamiltonian in pf -shell. An over-production problem of neutron-rich iron-group isotopes compared with the solar abundances is now found to be suppressed within a factor of about twice for the updated weak rates. Effects of screening on nucleosynthesis are investigated for explosion models of fast deﬂagration and slow deﬂagration with delayed detonation. The e-capture rates are reduced by the screening, especially by the screening effects on the ions. The production yields of most neutron-rich isotopes such as 50Ti, 54Cr and 58Fe are found to be suppressed most by the screening. The inclusion of the screening is desirable for precise evaluation of abundances of neutron-rich nuclides.

Highlights

We show that a new shell-model Hamiltonian, GXPF1J [1], can describe Gamow-Teller (GT) strengths and e-capture rates in p f -shell nuclei quite well
There was an over-production problem of neutron-excess iron-group isotopes compared with the solar abundances when e-capture rates of FFN were used
Screening effects on the production yields of elements in Type Ia SN explosion (SNe) compared with the solar abundances are investigated for the W7 and WDD2 explosion models [16]

Summary

Introduction

We show that a new shell-model Hamiltonian, GXPF1J [1], can describe Gamow-Teller (GT) strengths and e-capture rates in p f -shell nuclei quite well. Electron-capture rates at stellar environments are evaluated by using GT strength and phase space factor for the reaction. While both can describe spin properties of p f -shell nuclei very well, experimental GT strength distributions in 58Ni, for example, are better reproduced for GXPF1J than KB3G [3] in both n → p and p → n channels. The GXPF1J can reproduce B(M1) in 48Ca and experimental e-capture rates in p f -shell nuclei best among various shell-model and RPA calculations [4]. The screening effects on the rates and nucleosynthesis are discussed in Sect.

Nucleosynthesis of iron-group nucleides in Type Ia SN

Screening effects on the weak rates

Screening effects on the synthesis of iron-group nucleides