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

¹ Department of Physics, College of Humanities and Sciences, Nihon University, 3-25-40 Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan
² Research Institute of Stellar Explosive Phenomena, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka-shi, Fukuoka 814-0180, Japan
³ Center for Mathematical Sciences, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8580, Japan
⁴ Department of Physics, Western Michigan University, Kalamazoo, MI 49008, USA
⁵ School of Physics, Beihang University, Haidian-qu, Beijing 100083, People’s Republic of China
⁶ Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
⁷ Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
⁸ National Astronomical Observatory of Japan, 2-21-2 Osawa, Mitaka, Tokyo 181-8588, Japan

^* e-mail: suzuki.toshio@nihon-u.ac.jp

Published online: 24 February 2022

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.