Heat release in accreting neutron stars

Abstract

Observed thermal emission from accreting neutron stars (NSs) in a quiescent state is believed to be powered by nonequilibrium nuclear reactions that heat the stellar crust (deep crustal heating paradigm). We derive a simple universal formula for the heating efficiency, assuming that an NS has a fully accreted crust. We further show that, within the recently proposed thermodynamically consistent approach to the accreted crust, the heat release can be parametrized by the only one parameter -- the pressure $P_{\mathrm{oi}}$ at the outer-inner crust interface (as we argue, this pressure should not necessarily coincide with the neutron-drip pressure). We discuss possible values of $P_{\mathrm{oi}}$ for a selection of nuclear models that account for shell effects, and determine the net heat release and its distribution in the crust as a function of $P_{\mathrm{oi}}$. We conclude that the heat release should be reduced by a factor of few in comparison to previous works.

arXiv comment5 pages, 1 figure, 1 table + 5 pages supplemental material

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Cited by in corpus (7)

• Deep crustal heating for realistic compositions of thermonuclear ashes
• Gravitational radiation from thermal mountains on accreting neutron stars: sources of temperature non-axisymmetry
• Accreting neutron stars: heating of the upper layers of the inner crust
• Neutron star inner crust: reduction of shear modulus by nuclei finite size effect
• Crystallization in single and multicomponent Neutron Star crusts
• Nonequilibrium thermodynamics of accreted neutron-star crust
• Quiescent luminosities of transiently accreting neutron stars with neutrino heating due to charged pion decay