NASA is holding a press conference today in which new evidence for the existence of dark matter will be presented. There will be an audio feed and graphics on the web as soon as the conference starts. A comment at the Angry Physicist’s blog links to the abstract of the upcoming APJ paper which describes this “dark ring”:
The mass reconstruction of CL0024+17 obtained in such a way is remarkable. It reveals a ring-like dark matter substructure at r 75" surrounding a soft, dense core at r<50". We interpret this peculiar sub-structure as the result of a high-speed line-of-sight collision of two massive clusters 1-2 Gyr ago.
This suggests it might be a similar analysis to the bullet cluster evidence
of a while back.
[Update] Here’s the headline picture from the NASA mission page: