This is interesting - about Black Holes - could they account for all the Dark Matter?
https://www.forbes.com/sites/startsw...h=5604ab5829bb
Could Black Holes Be The Dark Matter Our Universe Needs?
Ethan Siegel - Senior Contributor
Jul 7, 2020,02:00am EDT
So what about the idea of black holes? After all, black holes:
are dark,
don't emit light,
can have an enormous amount of gravitation, and
definitely exist, unlike (at least most of) the particle candidates we've concocted for dark matter.
The idea that black holes could play a role in solving the dark matter puzzle is an old one, going back many decades.
The idea that our Universe's dark matter might be black holes is interesting and deserves scrutiny, and get revived periodically as new generations of scientists take an interest in the old idea for themselves. But the data simply doesn't support it. Black holes as dark matter are both highly constrained and disfavored for numerous reasons, both theoretical and observational. Until new evidence supporting them comes in, don't believe the hype surrounding them, no matter how fashionable it becomes.