Screening effect on electron capture in presupernova stars

Institute of Theoretical Physics, China West Normal University, Nanchong 637002, PR China e-mail: Liumq@cwnu.edu.cn;menquanliu@126.com

Received: 25 May 2006
Accepted: 12 October 2006

Abstract

Aims.With the new electron capture results from the improved GT resonance distribution, we analyzed the electron screening effect on electron capture at the presupernova stage.

Methods.The relativistically degenerate electron liquid screening potential derived from the linear response theory are adopted. The calculation of the electron capture rates is based on the shell-model. Both the change of electron energy and the shift in the threshold for electron capture in screening are taken into account.

Results. The results indicate that the influence of electron screening on the electron capture is prominent in high-density matter. As the improved electron capture rate is considered, screening effect on the electron capture rate increases by about 1 percent at  g/cm³.

Conclusions.The influence of screening on the electron capture reaction is about 10 percent for ⁵⁶Co at  g/cm³. Screening may affect the structure and evolution of presupernova and should be included in any precise simulation.