Are black holes and dark matter same?

Upending textbook explanations, astrophysicists from the University of Miami, Yale University, and the European Space Agency suggest that primordial black holes account for all dark matter in the universe.

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I’ll wait to see what kind of holes their opponents can pick in this idea.

Bubblecar said:

I’ll wait to see what kind of holes their opponents can pick in this idea.

Presumably they will pick sufficient black holes to provide exactly the mass required for dark matter.

The Rev Dodgson said:

Bubblecar said:

I’ll wait to see what kind of holes their opponents can pick in this idea.

Presumably they will pick sufficient black holes to provide exactly the mass required for dark matter.

Not too surprisingly, this was a popular idea shortly after dark matter was first discovered. It’s not difficult to show that that means that black holes much exist within our own solar system. So there was a search for them.

Stellar mass black holes within our solar system were rapidly ruled out because of lack of gravitational influence on the planets. Micer-scale black holes were ruled out becuse calcs showed that they would be rapidly attracted to the cores of the Sun and planets, and for the Sun that waought alter the brightness and neutrino flux so much that their existence is incompatible with the standard solar model.

That left primordial black holes of intermediate mass as a possibility, which would have to be present in very large numbers within our solar sysyem, and a seach for these by looking for their gravitational influence quickly ruled these out as well.

Black holes as dark matter also go by the name of “machos”, short for “macroscopic compact halo objects” which could be detected by microlensing events as they pass in front of stars in nearby galaxies. Looking for those found that machos are present in nowhere near the quantity sufficient (too small by more than a factor of ten) to explain dark matter.

Only a very small percentage of dark matter can be explained as black holes. Dark matter interacts only extremely weakly with ordinary matter. Black holes, on the other hand, interact very strongly with ordinary matter, giving off X-rays in detectable numbers when the interact.