Spin Light of neutrino in polarized matter

TL;DR

This work investigates how net spin polarization of dense astrophysical matter modifies the Spin Light of neutrino ($SLν$), a radiation driven by the neutrino magnetic moment in a medium. By solving the modified Dirac equation for neutrinos in polarized matter, the authors show that the radiation rate and angular distribution acquire a polarization factor $(1 + ζ\cos δ)$, enabling enhancement or suppression of $SLν$ and introducing observable asymmetries tied to the matter polarization and magnetic field. They compute the plasmon‑mass‑modified photon emission, derive the leading expressions for the total rate and power, and demonstrate that in the massless limit the radiation is left‑circularly polarized. The results imply potentially observable signatures in neutron stars and magnetars, linking internal matter polarization to the radiated neutrino signal and to sterile neutrino production, with implications for probing compact object interiors.

Abstract

The Spin Light of neutrino ($SLν$) is an electromagnetic radiation of the neutrino magnetic moment emitted when neutrino moves in external conditions (fields or matter). The effect can be of significance in the extremely dense matter of compact astrophysical objects such as neutron stars (NS). If detected, this radiation could provide a fair opportunity to study the properties of neutrinos and the medium through which they move, since the properties of the radiation depend on both. Motivated by the possibility of the nuclear matter spin-polarization, in this paper, we study the new properties to $SLν$ obtained under the influence of net matter polarization. We demonstrate that the polarization can enhance or completely suppress the radiation. Also, it introduces a characteristic asymmetry into the total radiation from the compact object, which could be an observable feature dependent on the matter polarization and the magnetic field inside the stellar (if the field is connected to the stellar matter polarization). The research may have implications for the physics of NS and magnetars, bringing us closer to the possibility of studying their internal structure.

Figures (1)

• Figure 1: Angular distribution of the radiation power in arbitrary units for the set of parameters $\delta = \pi/2$, $\zeta =1$, $\varphi =0$, $\tilde{n}/p = 0.01$: (a) -- the three-dimensional view, (b) -- the two-dimensional cut in the plane of vectors ${\bm \zeta}$ and ${\bf p}$.