Finally read this nice preprint by Forero-Romero & Arias: arxiv.org/abs/1805.03188…
They use an interesting approach to measure the overall asphericity of the distribution of the top 11 to 15 satellites around the MW and M31, and use it to compare to cosmological simulations.
They use an interesting approach to measure the overall asphericity of the distribution of the top 11 to 15 satellites around the MW and M31, and use it to compare to cosmological simulations.
One of the paper's main finding is that the MW system is highly exceptionally flattened. Similar satellite arrangements are rare in LCDM simulations. This agrees with what I've been saying, so for me this is reassuring, though not super exciting.
Their most exciting finding is buried in the text: they report that hydrodynamical cosmological simulations result in *less* flattened satellite systems than dark-matter only sims.
So much for "baryons solve the satellite plane problem".
So much for "baryons solve the satellite plane problem".
For Andromeda, in contrast, since they only look at the overall satellite distribution they find it to be in line with expectations. The M31 satellite plane consists of only a subset of all satellites, so this method won't see it.
My main concern is that they don't take observational biases into account, e.g obscuration by the MW disk. These comparisons also only look at the spatial distributions, the kinematic alignments indicative of rotating satellite planes increase the tension with LCDM substantially.
