Neutron Tunneling: A New Mechanism to Power Explosive Phenomena in Neutron Stars, Magnetars, and Neutron Star Mergers

Abstract

Neutron tunneling between neutron-rich nuclei in inhomogeneous dense matter encountered in neutron star crusts can release enormous energy on a short timescale to power explosive phenomena in neutron stars. In this work, we clarify aspects of this process that can occur in the outer regions of neutron stars when oscillations or cataclysmic events increase the ambient density. We use a time-dependent Hartree–Fock–Bogoliubov formalism to determine the rate of neutron diffusion and find that large amounts of energy can be released rapidly. The roles of nuclear binding, two-body interaction, and pairing in neutron diffusion times are investigated. We consider a one-dimensional quantum diffusion model and extend our analysis to study the impact of diffusion in three dimensions. We find that these novel neutron transfer reactions can generate energy in the amount of ≃ 1040–1044 erg under suitable conditions and assumptions.

Neutron diffusion in magnetars as a source of astrophysical bursts

“…We have shown that significant energy release can occur by neutron diffusion in inhomogeneous neutron matter and we infer [7] that neutron diffusion in such environments can be enhanced by the presence of multiple neighbors. Neutrons tend to flow to states with nearly the same single-particle energies due to an effect known as resonant tunneling.…”

“…In this work (see also Ref. [7]), we have reported a microscopic TDHFB calculation for the neutron diffusion rates in transient neutron stars due to neutron diffusion/tunneling from neutron-rich to neutron-poor regions. We considered neutron clumps consisting of 20, 40, 80 and neutrons taking into account that nuclear barriers will form between the impurities and the surroundings.…”

“…Recently, the current authors have explored [7] the physics of isospin diffusion in inhomogeneous neutron media due to tunneling, considering the flow of single neutrons and of neutron-pairs passing through the potential barriers generated by the strong interaction mean-field. Neutron-rich regions were emulated and the neutron diffusion rates to neutronpoor regions were calculated.…”