Dark matter that talks to itself could explain galaxy mystery | New Scientist
https://www.newscientist.com/...5-100-dark-matter-that-talks-to-itself-could-explain-galaxy-mystery/
DARK matter might talk to itself. The mysterious substance that outweighs all visible matter
in the cosmos might be best explained if it’s able to interact with itself via an invisible force.
Take a look at any image of a galaxy and you will see that the centre is the brightest. With so much light – and
therefore mass – concentrated there, astronomers expected central objects to orbit faster than those on the outer rim.
But in the early 20th century, astronomers were surprised to find that galaxies’ outer stars appear to move about as fast
as their inner stars, suggesting that there is more matter that doesn’t meet the eye. The name given to the invisible stuff
is dark matter, and the standard paradigm suggests it is composed of weakly interacting massive particles, or WIMPs.
Now new research on galactic rotation curves – graphs showing the orbital speeds of stars versus their distance from
the centre of the galaxy – suggests the story might not be so simple.