Science published last week (02/02/2018) a paper from O. muller et Al. (https://arxiv.org/pdf/1802.00081.pdf)
"A whirling plane of satellite galaxies around Centorus A challenges cold dark matter cosmology".
The authors report measurements of the velocities of 16 dwarf galaxies around Centorus A, a nearby galaxy (a nice picture here : https://en.wikipedia.org/wiki/Centaurus_A).
What they find is surprising : the galaxies are coherently rotating around centorus A, as you can see for yourself on this plot :
On the left panel, blue triangles indicate approaching galaxies and the red ones indicate receding galaxies. The upper right panel simply shows a zoom at Centaurus A, and the bottom right panel is a 3-D map of the 16 dwarf galaxies and their velocities.
This is surprising because, after our own Milky-Way and (possibly) Andromeda, this is the third case of such corotating satellite galaxies, a dynamic that is not favored at all by the best current cosmological model, \(\Lambda\)-CDM (Dark Energy and Cold Dark Matter) which predicts that less than 5 per 1000 galaxies should exhibit such behavior.