Thermal conductivity and phase separation of the crust of accreting neutron stars

C. J. Horowitz, O. L. Caballero, D. K. Berry

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33 Scopus citations

Abstract

Recently, crust cooling times have been measured for neutron stars after extended outbursts. These observations are very sensitive to the thermal conductivity κ of the crust and strongly suggest that κ is large. We perform molecular dynamics simulations of the structure of the crust of an accreting neutron star using a complex composition that includes many impurities. The composition comes from simulations of rapid proton capture nucleosynthesis followed by electron captures. We find that the thermal conductivity is reduced by impurity scattering. In addition, we find phase separation. Some impurities with low atomic number Z are concentrated in a subregion of the simulation volume. For our composition, the solid crust must separate into regions of different compositions. This could lead to an asymmetric star with a quadrupole deformation. Observations of crust cooling can constrain impurity concentrations.

Original languageEnglish
Article number026103
JournalPhysical Review E
Volume79
Issue number2
DOIs
StatePublished - 2 Feb 2009
Externally publishedYes

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