"Xie and Kawana added several ingredients to their model, which is described in a paper published in June to the preprint database arXiv. (The paper has not yet been peer-reviewed.)"
I read this 7 page report with 17 equations in it
I note this from the arXiv paper. "PBHs with mass between 10^9 g and 10^17 g evaporate between the Big Bang Nucleosynthesis (BBN) and today, leaving impacts on the BBN, Cosmic Microwave Background and extragalactic and Galactic γ-ray backgrounds, which in turn put stringent constraints on the PBH abundance."
This is in the mass range of Halley's comet some 10^17 g and other comets estimated 10^14 g to 10^19 g, Allen's Astrophysical Quantities, Fourth Edition, 2000. Also the paper states, "PBHs with mass larger than 5.1 × 10^14 g can survive until today. Such PBHs can be probed/constrained by Hawking radiation (if MPBH . 10^17 g), gravitational lensing, dynamical processes, cosmic structure, etc [6–8]. The abundance is usually described by the fraction of PBH to DM..."
Other reports at space.com discuss PBHs too. These are primordial black holes that appear now in the universe as this space.com report indicates. "But the earliest moments of the universe featured some pretty mind-boggling physics. Perhaps whatever was going on back then spawned trillions of smaller black holes. Those black holes could persist to the present day, potentially solving the dark matter riddle."
Indeed, we have *mind-boggling physics* used now in the BB model. Here is an example. Alan Guth provides inflation scale 10^-53 m to 1 m size today, Quantum Fluctuations in Cosmology and How They Lead to a Multiverse,
https://ui.adsabs.harvard.edu/abs/2013arXiv1312.7340G/abstract, December 2013. "This means that a distance scale of 1 m today corresponds to a length of only about 10^−53 m at the start of inflation, 18 orders of magnitude smaller than the Planck length (∼ 10^−35 m)." That is something to ponder
10^-53 m and now the universe expanded to some 93 billion light years in diameter,
https://phys.org/news/2021-03-myths-big.html, Five myths about the Big Bang 22-Mar-2021, "That which we call the observable universe is a bubble surrounding us that is 93 billion light-years in diameter." So applying the scale where 1 meter today = 10^-53 m at the start, we have the universe begin ~ 8.8 x 10^-27 m size and expand to ~ 8.8 x 10^26 m size today in 13.8 billion years, ~ 4.352 x 10^17 seconds. Space and time expands by some 10^53 order of magnitude or more to create the universe we see today, quite a cauldron at the start. And now I can add PBHs created, apparently before BBN. What size was the universe when the PBHs appeared?
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