Astrophysical bounds on mirror dark matter derived from binary pulsars timing data

TL;DR

This paper uses binary pulsar timing data to set stringent astrophysical bounds on neutron to mirror neutron transitions, constraining mirror dark matter models and their particle interaction parameters.

Contribution

It provides the first astrophysical limits on neutron-mirror neutron mixing based on binary pulsar observations, surpassing previous experimental bounds.

Findings

Stringent upper limits on neutron to mirror neutron transition rates.

Constraints on mirror dark matter particle interactions.

Limits are stronger than those needed to explain neutron decay anomalies.

Abstract

Mirror Dark Matter (MDM) has been considered as an elegant framework for a particle theory of Dark Matter (DM). It is supposed that there exists a dark sector which is mirror of the ordinary matter. Some MDM models allow particle interactions mirror and ordinary matter, in addition to the gravitational interaction. The possibility of neutron to mirror neutron transition has recently been discussed both from theoretical and experimental perspectives. This paper is based on a previous work in which we obtained stringent upper limits on the possibility of converting neutrons to mirror neutrons in the interiors of neutron stars, by using timing data of binary pulsars. Such a transition would imply mass loss in neutron stars leading to a significant change of orbital period of neutron star binary systems. The observational bounds on the period changes of such binaries, therefore put strong limits on the above transition rate and hence on the neutron -- mirror-neutron mixing parameter $\epsilon'$. Our limits are much stronger than the values required to explain the neutron decay anomaly via $n-n'$ mixing.