A Possible Detection of Dark Matter in a Dwarf Galaxy!

[n2doc]

by Ben Cook

Most readers of this blog have likely heard of dark matter before; you may even take it for granted that it exists. A huge body of astronomical research exists offering conclusive evidence for some kind of mass in the universe which a) exerts gravitational force on regular matter, b) doesn’t emit light, and c) seems to be 5 times more abundant than regular matter. Evidence for this extra mass comes from gravitational effects, including

The high velocities of stars/gas in galaxies, and of galaxies in larger clusters
The oscillations of the CMB power spectrum
Direct measurements of cluster masses from gravitational lensing (Fig. 1)
These observations indicate that there is much more mass in the universe than we can see with light.

But these gravitational clues are only “indirect evidence” for dark matter’s existence. It is like seeing a dancing marionette puppet (the gravitational effects), and inferring there must be strings (dark matter) to make it move.

Some models (such as Modified Newtonian Dynamics) try to explain these gravitational effects through a subtle change to General Relativity. These changes could make gravity stronger in certain places without requiring more mass. This explanation is like saying the puppet is held up by magnets: it could explain the puppet’s movement just as well as strings could. To prove dark matter really exists, we must actually see the strings, not just the puppet. Today’s paper offers some of the best evidence yet!

more

http://astrobites.org/2015/03/18/a-possible-detection-of-dark-matter-in-a-dwarf-galaxy/