出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：In the study of the crust of an accreting neutron star, electron capture rates on nuclei in the mass
range A=20-106 from the neutron deficient region to the neutron drip line are needed. At the
low temperatures typical of a neutron star crust (T9 0:4) the determination of the phase space
poses a problem since the integrand is very sharply peaked and an error in finding the peak using
numerical differentiation or cruder maximum-locator methods will result in inaccuracies at the
energies where the integrand has its highest value. In this work we present a global set of temperature
and density-dependent continuum electron capture rates and a fast phase space calculator
valid for low temperatures. The electron capture rates have been calculated using Gamow-Teller
strength distributions from the quasi-particle random-phase approximation (QRPA, [1]) nuclear
model. We present a new analytic technique to carry out the evaluation of the phase space for
electron capture that is fast enough to be implemented in a reaction network. The integral is split
into two separate terms at the chemical potential of the electron gas, thus eliminating the need to
find the peak of the integrand. The Coulomb correction, which is essentially constant over the
range of energies considered, is taken outside the integral and is evaluated at a suitable effective
energy which is a function of the charge of the capturing nucleus, the temperature, the chemical
potential and the threshold. We compare our calculated electron capture rates to the compilations
by Fuller, Fowler and Newman [2] and by Langanke and Martínez-Pinedo [3].
