Public Broadcasting System | Nova Next | 2016 Dec 08
[img3="Artist’s impression of the expected dark matter distribution around the Milky Way Credit: ESO/L. Calçada"]https://www-tc.pbs.org/wgbh/nova/next/w ... 00x788.jpg[/img3][hr][/hr]Approximately every 35 million years, a comet careens from outer space and lays waste to the Earth. For nearly two decades, researchers at Harvard have attempted to understand this “periodicity” of mass extinction. Now, in a paper recently submitted to Astrophysical Journal Letters, two Harvard graduate students used the 250 million-year-old crater record to show how a disk of dark matter suffusing the galaxy could spark mass extinctions.
Most scientists agree that the observable stuff in our galaxy, concentrated in a disk, is surrounded by a diffuse halo of dark matter. But some maintain that a portion of dark matter exists in a separate, condensed form—a “dark disk” located both on top of and within our own flat galaxy. It’s the relative movements of our galaxy and this disk that may trigger events that lead to mass die-offs.
“There’s a cycle in our galaxy; the solar system bobs up and down through the plane of the disk-shaped galaxy—we’re pulled towards the plane, we go through it, we overshoot, we go back,” said Michael Rampino, professor of biology at New York University. “The folks at Harvard are proposing that there is a thin disk of concentrated dark matter, and the solar system moves through it every 35 million years or so.” ...
Mass Extinctions and a Dark Disk - Eric David Kramer, Michael Rowan
- arXiv.org > astro-ph > arXiv:1610.04239 > 13 Oct 2016