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 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 we 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.

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• Nuclear matter in neutron stars
• Neutron stars & pulsars