There are 2 recent papers about Primordial Black Holes and Dark Matter, both are in Physical Review Letters . In one John Hopkins University scientists say the rate that LIGO discovered Black Hole mergers is consistent with Dark Matter being made entirely of Primordial Black Holes.
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.201301 In the other paper Kyoto University scientists say the discovery rate can account for some but not all of Dark Matter, so there must be something else in addition. http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.061101 The difference between the 2 papers comes from different assumptions about the very early universe less than a second after the Big Bang and the rate Black Holes would be formed in pairs. Both agree that Primordial Black Holes would tend to have more elliptical orbits than astrophysical ones formed from dead stars which would usually be more circular, and LIGO can tell the difference. We need more data and fortunately LIGO should come back online any day now, and VIRGO in Italy too, so before long we should know who is right. Another Dark matter candidate is a hypothetical light particle, the Axion. Recently Maurizio Giannotti suggested that the observed unexpected rapid cooling of white dwarfs and neutron stars could be explained by the stars radiating away energy in the form of Axions. One good thing about Axions is that unlike WIMPS the Axions theory doesn't have a lot of wiggle room, so within a few years the Axion Dark Matter Experiment (ADMX) should be able to find Axions or prove they don't exist. Unlike WIMPS Axions react (weakly) with a magnetic fields and cause a Axion to be converted to a microwave photon which can be detected by ADMX, assuming Axions are not just the figment of a physicist's imagination. In another development that may or may not be related to Dark Matter there is increasing evidence (although not yet proof) of a fifth fundamental force that effects only electrons and neutrons and only at very close range: https://news.uci.edu/research/uci-physicists-confirm- possible-discovery-of-fifth-force-of-natur John K Clark -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
