Enhanced Nuclear Binding Near the Proton Dripline Opens Possible Bypass of the ${}^{64}\mathrm{Ge}$ rp-process Waiting Point

Abstract

We performed astrophysics model calculations with updated nuclear data to identify a possible bypass of the ${}^{64}\mathrm{Ge}$ waiting-point, a defining feature of the rapid-proton capture (rp-) process that powers type-I x-ray bursts on accreting neutron stars. We find that the rp-process flow through the ${}^{64}\mathrm{Ge}$ bypass could be up to 36\% for astrophysically relevant conditions. Our results call for new studies of ${}^{65}\mathrm{Se}$, including the nuclear mass, ${\hat{I}}^2$-delayed proton emission branching, and nuclear structure as it pertains to the ${}^{64}\mathrm{As}(p,{\hat{I}}^3)$ reaction rate at x-ray burst temperatures.

Accepted to ApJ