“it does not emit or absorb any radiation “
so then, is it matter?
Must be totally inert and at zero degrees absolute for that to happen. Doesn’t look like it’s matter. Better find another explanation.
it doesn't matter.
Reconciling quantum mechanics and relativity requires dark energy and dark matter to exist. We are (reasonably) sure at this point that both those theories are correct.
So there are two main possibilieis, to my mind.
Assuming the universe really exists in a multi-dimensional reality, only three (or four) of which we can perceive, possibly the extra mass and energy exists in some of those other dimensions.
Or quantum and relativity theory are fundamentally flawed and we need to go back to the drawing board and start over.