Dark matter, dark energy, and alternate models: A review

TL;DR

This review discusses the current understanding, candidates, and models of dark matter and dark energy, including alternative theories and methods to distinguish between them, highlighting ongoing challenges and future prospects.

Contribution

It provides a comprehensive overview of dark matter and dark energy candidates, models, and alternatives, including recent observational constraints and detection efforts.

Findings

Multiple viable dark matter candidates identified

Current observations favor cosmological constant for dark energy

Alternative theories like MOND and modified gravity are considered

Abstract

The nature of dark matter (DM) and dark energy (DE) which is supposed to constitute about 95% of the energy density of the universe is still a mystery. There is no shortage of ideas regarding the nature of both. While some candidates for DM are clearly ruled out, there is still a plethora of viable particles that fit the bill. In the context of DE, while current observations favour a cosmological constant picture, there are other competing models that are equally likely. This paper reviews the different possible candidates for DM including exotic candidates and their possible detection. This review also covers the different models for DE and the possibility of unified models for DM and DE. Keeping in mind the negative results in some of the ongoing DM detection experiments, here we also review the possible alternatives to both DM and DE (such as MOND and modifications of general relativity) and possible means of observationally distinguishing between the alternatives.