Mostly Mute Monday: Dark Matter's Secrets Revealed By Colliding Galaxy Clusters (Synopsis)

"It may be that ultimately the search for dark matter will turn out to be the most expensive and largest null result experiment since the Michelson-Morley experiment, which failed to detect the ether." -John Moffat

Dark matter is a puzzle that's now more than 80 years old: the presence of all the known, observable, detectable normal matter -- the stuff in the standard model -- cannot account for the gravitation of the astronomical objects we observe. But despite our inability to create or detect it in a laboratory, we're certain of its existence in the Universe.

Image credit: X-ray: NASA/CXC/UCDavis/W.Dawson et al; Optical: NASA/STScI/UCDavis/W.Dawson et al.

The true test of this comes from colliding galaxy clusters, which show a distinct separation between all the known "normal" components, which collide, heat up and emit light, and the gravitational components, which very clearly don't. At this point, over a dozen distinct colliding clusters show this effect, from some of the smallest known galactic groups to the largest colliding cluster in the Universe: El Gordo.

Image credit: NASA, ESA, J. Jee (Univ. of California, Davis), J. Hughes (Rutgers Univ.), F. Menanteau (Rutgers Univ. & Univ. of Illinois, Urbana-Champaign), C. Sifon (Leiden Obs.), R. Mandelbum (Carnegie Mellon Univ.), L. Barrientos (Univ. Catolica de Chile), and K. Ng (Univ. of California, Davis).

Come get the whole thing on Mostly Mute Monday!