Cherenkov radiation from stars constrains hybrid MOND dark matter models

We propose a new method to constrain alternative models for dark matter with observations. Specifically, we consider hybrid models in which cold dark matter (CDM) phenomena on cosmological scales and Modified Newtonian Dynamics (MOND) phenomena on galactic scales share a common origin. Various such models were recently proposed. They typically contain a mode that is directly coupled to matter (for MOND) and has a nonrelativistic sound speed (for CDM). This allows even non-relativistic objects like stars to lose energy through Cherenkov radiation. This is unusual. Most modified gravity models have a relativistic sound speed, so that only high-energy cosmic rays emit Cherenkov radiation. We discuss the consequences of this Cherenkov radiation from stars.

Automated summary

A new method is proposed to constrain alternative models for dark matter with observations, focusing on hybrid models that combine CDM and MOND phenomena. These models feature a mode directly coupled to matter with a nonrelativistic sound speed, allowing even non-relativistic objects like stars to emit Cherenkov radiation and lose energy. This diverges from most modified gravity models which have a relativistic sound speed.