Question

Why would be axions be a candidate for warm/cold dark matter?

Answer 1

When we look out at the Universe – even with the most powerful of telescopes – we can only see a fraction of the matter we know must be there. In fact, for every gram's worth of atoms in the Universe, there are at least five times more invisible material called 'dark matter'. So far scientists have failed to detect it, despite spending decades searching.

Answer 2

Explanation:

Axions, very light particles with a specific type of self-interaction that makes them a suitable CDM candidate. Axions have the theoretical advantage that their existence solves the strong CP problem in quantum chromodynamics, but axion particles have only been theorized and never detected.