Estimate for the neutrino magnetic moment from pulsar kick velocities induced at the birth of strange quark matter neutron stars

TL;DR

This paper estimates the neutrino magnetic moment by analyzing how neutrino chirality flips in strange quark matter neutron stars, linking it to observed pulsar kick velocities and providing a more stringent bound than previous models.

Contribution

It introduces a novel method to constrain the neutrino magnetic moment using pulsar kick velocities and models the star core as strange quark matter for the first time.

Findings

Estimated neutrino magnetic moment: ~3.6 x 10^{-18} μ_B

Neutrino chirality flip can produce observed pulsar velocities

Results are consistent with typical neutron star conditions

Abstract

We estimate the magnetic moment of electron neutrinos by computing the neutrino chirality flip rate that can occur in the core of a strange quark matter neutron star at birth. We show that this process allows neutrinos to anisotropically escape, thus inducing the star kick velocity. Although the flip from left- to right-handed neutrinos is assumed to happen in equilibrium, the no-go theorem does not apply because right-handed neutrinos do not interact with matter and the reverse process does not happen, producing the loss of detailed balance. For simplicity, we model the star core as consisting of strange quark matter. We find that even when the energy released in right-handed neutrinos is a small fraction of the total energy released in left-handed neutrinos, the process describes kick velocities for natal conditions, which are consistent with the observed ones and span the correct range of radii, temperatures and chemical potentials for typical magnetic field intensities. The neutrino magnetic moment is estimated to be $\mu_\nu \sim 3.6 \times 10^{-18}\mu_B$, where $\mu_B$ is the Bohr magneton. This value is more stringent than the bound found for massive neutrinos in a minimal extension of the \mbox{standard model.}