Transport properties of degenerate electrons in neutron star envelopes and white dwarf cores

TL;DR

This paper presents new calculations of thermal and electrical conductivities for degenerate electrons in neutron star envelopes and white dwarf cores, considering various elements and physical conditions, with implications for astrophysical modeling.

Contribution

The study introduces improved models for electron conductivities incorporating advanced ion structure factors, accounting for multi-phonon processes and electron-band effects, enhancing previous estimates.

Findings

Transport coefficients differ significantly from earlier models in key temperature ranges.

New analytical fits for conductivities facilitate astrophysical applications.

Results cover a wide range of densities and compositions relevant to stellar environments.

Abstract

New calculations of the thermal and electrical electron conductivities are performed for a broad range of physical parameters typical for envelopes of neutron stars and cores of white dwarfs. We consider stellar matter composed of astrophysically important chemical elements from H to Fe in the density range from 10^2-10^4 g/ccm up to 10^7-10^{10} g/ccm, where atoms are fully ionized and electrons are strongly degenerate. We have used modified ion structure factors suggested in physics/9811052. In the ion liquid, these modifications take into account, in an approximate way, instantaneous electron-band structures that reduce the electron-ion scattering rate. In crystallized matter, the new structure factors include multi-phonon processes important at temperatures not very much lower than the melting temperature T_m. The transport coefficients obtained differ significantly from those derived earlier in the important temperature range T_m/5 < T < 5 T_m. The results of our numerical calculations are fitted by analytical expressions convenient for astrophysical applications.