Is dark matter made of black holes? http://www.sciencemag.org/news/2017...ily_2017-02-09&et_rid=41087911&et_cid=1152979 SHARE Please Register or Log in to view the hidden image! Could dark matter consist of primordial black holes, as numerous as the stars? It’s an old, improbable idea, but it made a Lazarus-like comeback a year ago, when the discovery of gravitational waves suggested that the cosmos abounds with unexpectedly heavy black holes. With decades-long searches failing to find the hypothetical dark matter particles that theorists have favored, physicists are turning to more radical ways of explaining the universe’s missing mass. “It’s a nutty idea,” says Marc Kamionkowski, a theorist at Johns Hopkins University in Baltimore, Maryland, whose team made the case for black hole dark matter here last week at a meeting of the American Physical Society. “But every idea of what dark matter might be is a nutty idea.” Others are skeptical, and new studies add to the doubts. For the idea to hold up, “I think you need some miracles,” says Daniel Holz, a theorist at the University of Chicago in Illinois. Ordinary black holes form when individual stars collapse, and were thought to top out at about 15 times the mass of the sun. And the supermassive black holes that lurk in galactic centers swallow billions of stars. But astrophysicists didn’t see how collapsing stars could form black holes of intermediate masses. That’s why it was a surprise when physicists with the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced in February 2016 that they had detected ripples in space from the violent merger of two black holes 29 and 36 times as massive as our su
Perhaps he or she can read. Please Register or Log in to view the hidden image! Seriously though, if you read it up, you will be able to find descriptions of the observations that led to the dark matter hypothesis. In fact I learnt one piece of evidenced from a recent thread on this forum, here: http://www.sciforums.com/threads/galactic-unit.158938/ Posts 12-20 cover the subject of galactic rotation and the observed fact that the orbital velocities of stars round the galactic centre do not obey the laws one would expect, if all the matter were in the form of the stars we can detect.
