Deep crustal heating by neutrinos from the surface of accreting neutron stars

Abstract

We present a new mechanism for deep crustal heating in accreting neutron stars. Charged pions (${\pi }^{+}$) are produced in nuclear collisions on the neutron star surface during active accretion and upon decay they provide a flux of neutrinos into the neutron star crust. For massive and/or compact neutron stars, neutrinos deposit $\approx 1\text{–}2\mathrm{MeV}$ of heat per accreted nucleon into the inner crust. The strength of neutrino heating is comparable to the previously known sources of deep crustal heating, such as from pycnonuclear fusion reactions, and is relevant for studies of cooling neutron stars. We model the thermal evolution of a transient neutron star in a low-mass X-ray binary, and in the particular case of the neutron star MXB~1659-29 we show that additional deep crustal heating requires a higher thermal conductivity for the neutron star inner crust. A better knowledge of pion production cross sections near threshold would improve the accuracy of our predictions.

12 pages, 9 figures, 3 tables; [Added a new figure and edited the text in response to Referee's remarks and suggestions]

References in corpus (14)

• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• The NANOGrav Nine-year Data Set: Mass and Geometric Measurements of Binary Millisecond Pulsars
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• Models of crustal heating in accreting neutron stars
• Equation of state of superfluid neutron matter and the calculation of ${}^1{S}_0$ pairing gap
• Cooling of the crust in the neutron star low-mass X-ray binary MXB 1659-29
• Rapid neutrino cooling in the neutron star MXB 1659-29
• A lower limit on the heat capacity of the neutron star core
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Cited by in corpus (5)

• GW190814: Impact of a 2.6 solar mass neutron star on nucleonic equations of state
• Bayesian refinement of covariant energy density functionals
• Impacts of the direct URCA and Superfluidity inside a Neutron Star on Type-I X-Ray Bursts and X-Ray Superbursts
• Crust composition and the Shallow Heat Source in KS 1731-260
• Quiescent luminosities of transiently accreting neutron stars with neutrino heating due to charged pion decay