Notes on Hidden Mirror World

TL;DR

This paper discusses Mirror Matter as a viable dark matter candidate, exploring its properties, implications for astrophysical observations, and potential effects on cosmic structures, while clarifying misconceptions about virial concepts and particle interactions.

Contribution

It provides a comprehensive review of Mirror Matter dark matter models, including derivations, observational constraints, and astrophysical implications, highlighting their viability and differences from other models.

Findings

Limits on particle self-interaction cross-sections are not strict for macroscopic bodies.

Heating effects of Mirror Matter stars on interstellar medium are weak but potentially observable.

Neutron star heating by M-baryon accretion is likely negligible.

Abstract

A few remarks on Dark Matter (DM) models are presented. An example is Mirror Matter which is the oldest but still viable DM candidate, perhaps not in the purest form. It can serve as a test-bench for other analogous DM models, since the properties of macroscopic objects are quite firmly fixed for Mirror Matter. A pedagogical derivation of virial theorem is given and it is pointed out that concepts of virial velocity or virial temperature are misleading for some cases. It is shown that the limits on self-interaction cross-sections derived from observations of colliding clusters of galaxies are not real limits for individual particles if they form macroscopic bodies. The effect of the heating of interstellar medium by Mirror Matter compact stars is very weak but may be observable. The effect of neutron star heating by accretion of M-baryons may be negligible. Problems of MACHOs as Mirror Matter stars are touched upon.