Smoke and mirrors: Neutron star internal heating constraints on mirror matter

TL;DR

This paper proposes using neutron star temperatures to constrain mirror neutron mixing, providing a new astrophysical method that surpasses laboratory limits for a wide range of mass splittings.

Contribution

It introduces a novel astrophysical probe of mirror neutrons via neutron star heating, extending constraints to much larger mass splittings than laboratory experiments.

Findings

Derived new constraints from neutron star PSR 2144-3933 observations.

Showed heating mechanism applies to other neutron disappearance channels.

Highlights potential for future telescope observations to detect or constrain mirror matter.

Abstract

Mirror sectors have been proposed to address the problems of dark matter, baryogenesis, and the neutron lifetime anomaly. In this work we study a new, powerful probe of mirror neutrons: neutron star temperatures. When neutrons in the neutron star core convert to mirror neutrons during collisions, the vacancies left behind in the nucleon Fermi seas are refilled by more energetic nucleons, releasing immense amounts of heat in the process. We derive a new constraint on the allowed strength of neutron--mirror-neutron mixing from observations of the coldest (sub-40,000 Kelvin) neutron star, PSR 2144$-$3933. Our limits compete with laboratory searches for neutron--mirror-neutron transitions but apply to a range of mass splittings between the neutron and mirror neutron that is 19 orders of magnitude larger. This heating mechanism, also pertinent to other neutron disappearance channels such as exotic neutron decay, provides a compelling physics target for upcoming ultraviolet, optical and infrared telescopes to study thermal emissions of cold neutron stars.