Comments on: Primordial Black Holes Could Solve Dark Matter Mystery

By: Robert Crowley

Robert Crowley — Sat, 02 Jul 2016 22:08:18 +0000

Wouldn’t Primordial Black Holes at the low end of the proposed mass range have evaporated by now? I know a stellar mass singularity can last until now and well beyond, and supermassive ones will be around to watch the heat death of the rest of the universe. But wouldn’t one with the mass of a mountain have ceased to exist after ~13.8 billion years due to Hawking radiation? (Which is why, even if the LHC produced a quantum-scale singularity during a collision event, it would not be the world eating threat that uninformed doomsayers love to rant about. It would evaporate far too quickly to grow larger.) And what part of the predicted mass range do most of them fall into?
Is there any evidence that the gravitational influence of dark matter has gotten measurably weaker since the time when these would have formed? Or would the smaller ones have been more likely to have merged into larger ones by now? Does the evaporation of Primordial Black Holes possibly in some way account for any or all of the Dark Energy? While I get that Hawking Radiation is theorized to be caused by virtual particle pairs, and the ‘radiated’ particle is just as likely to pop back out of existence and into the local vacuum energy field, wouldn’t that still be a net energy increase? With enough of an increase in energy being dumped into Spacetime in this fashion, could it not cause expansion?
Sorry, I know that’s a lot of questions. But your excellent post spurred my imagination.

By: RichK

RichK — Thu, 02 Jun 2016 14:22:21 +0000

I/don’t/understand/how/the/distribution/of/matter/was/locally/dense/enough/and/the/force
of/gravity/strong/enough/in/the/first/few/milliseconds/for/such/massive/black/holes/to/form.

By: Jean Tate

Jean Tate — Tue, 31 May 2016 13:39:59 +0000

Interesting!

I would think there are many ways to test this idea, beyond what’s in the cited Kashlinsky paper.

For example, how consistent is the distribution of PBHs (per Kashlinsky) with the many MACHO searches (e.g. OGLE)? As Kashlinsky notes, PBHs would interact with their environments; in the inter-cluster and inter-galactic medium (IGM), how would that interaction affect the relative abundances of the primordial isotopes? Interactions between PBHs and IGM in the jets and lobes of extended radio sources would also likely leave observable footprints, in both the x-ray and IR; sorta a local version of what Kashlinsky says produced a component of the CIB, at very high redshift.

I wonder if any of the peer reviewers asked Kashlinsky about these tests (the document is “in press”, so apparently has already undergone peer review, and found to be OK)?