I do like the "issing satellites problem". But I'm very skeptical of this claim.
Although there are hints that the luminous satellite distribution is anisotropic [6, 13, 16–18], we assume it is sufficiently isotropic and spherical to be separable.
No, there's no "hint", it just is. Look, you can see it for yourself :
There it is, big as life. You can't just pretend it might not exist. And corrections for the incompleteness of surveys and the zone of avoidance (where the Milky Way blocks the view) have already been made and found to be minor. Also, while I think the work of Kroupa, Ibata, Pawlowski et al. is just wrong in many regards for the claims of other satellite planes around other galaxies, not citing them at all doesn't seem right.
Star formation in low-mass halos has been demonstrated to be suppressed by reionization and feedback. The discovery of many new dwarfs below the luminosity limit of the classical dwarfs have also closed the gap, as has the understanding that completeness corrections for the new dwarfs are large. In this Letter, we show that such corrections imply that the number of satellite galaxies that inhabit the Milky Way is consistent with the number of luminous satellites predicted by CDM.
Yes, but this has been known since Simon & Geha 2007. You can solve the problem, with enough complexity. The difficult part is not showing that any solution exists (which is what I think they've done here), but that any particular solution is the correct one. You need to show that the parameters required for the explanation are the ones which are actually true in reality.
https://arxiv.org/abs/1711.06267
I was just going to link you to this in the morning! :D
ReplyDeleteSo CDM is more likely after this? Or is this not helping much?
ReplyDeleteFred Beckhusen It probably doesn't change anything. It's been known since 2007 that you can solve the missing satellite problem, if you throw enough extra physics at it and tune everything just right. That doesn't mean that solution is actually the right one, though.
ReplyDeleteThe other big problem with this is that they're only considering satellites. But now it seems as though the problem is much more general : there are fewer isolated galaxies than expected as well, in many different environments. So removing the detectable gas and stars by tidal encounters (which they say is the main correction to the standard model) can't be the general solution : it will work for the Milky Way satellites, but not for isolated galaxies that have nothing else to interact with.
That said, being able to show that CDM can work is still better than showing that it can't work, even if it doesn't show that the result is actually correct. But again, that's been known for a decade. What's new here, and may or may not be more useful generally (I'm not going to go through them and check), is that they produce analytic equations to account for the corrections due to different processes. Which is nice, but a very far cry from being able to claim, "mystery solved".