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One of the numerous options for dark matter consist of having it made of black holes that are remanent of the primordial universe.

More precisely, those are black holes that do not originate from the collapse of a star but are instead another class of black holes that have been created during the very early days of the universe. Such black holes are in general expected to be massive. We talk about MACHOS (i.e. massive compact halo objects), although in principle the mass is a free parameters.

Then we have two things:

  • The massive guys are still there, they form dark matter and there are numerous constraints on the theory. However, it is not entirely excluded (anything that is not excluded is alive). The signatures are varied (microlensing, supernovae, etc.)
  • The less massive guys are in principle evaporated today due to Hawking radiation. The point is that this can be avoided by modifying the theory (that is the topic of the present post and a very recent novelty theoretically speaking).

I hope I clarified a little. Otherwise, please come back to me!