B Rutgers finds a transparent Einstein Cross - apparently a dark matter "halo".

[.Scott]

TL;DR Summary

Using NOEMA and ALMA in Chile, astronomers at Rutgers, New Brunswick find five images of galaxy Hers-3 in an Einstein Cross pattern, but with the central image still visible. So, apparently, gravitational lensing of something very heavy and very transparent.

The formal paper is here.

The Rutgers University news has published a story about an image being closely examined at their New Brunswick campus.
Here is an excerpt:

Computer modeling of the gravitational lens by Keeton and Eid showed that the four visible foreground galaxies causing the gravitational bending couldn’t explain the details of the five-image pattern. Only with the addition of a large, invisible mass, in this case, a dark matter halo, could the model match the observations. “We tried every reasonable configuration using just the visible galaxies, and none of them worked,” said Keeton, also a professor in the Department of Physics and Astronomy and a co-author of the study. “The only way to make the math and the physics line up was to add a dark matter halo. That’s the power of modeling. It helps reveal what you can’t see.”

I find it interesting because this single observation eliminates some of the wilder "theories" about the nature of dark matter.
And I wouldn't be surprised if it eventually allows us to further characterize dark matter.

 

[Jaime Rudas]

I find it interesting because this single observation eliminates some of the wilder "theories" about the nature of dark matter.

I think you underestimate the enormous retrospective adaptability that these "theories" have always demonstrated.