I have been recently interested in how halos made of standard model particles could be formed and behave.
After asking some questions in this site, I was told about how neutrinos could form such halos.
One good reference that I was given is arxiv:hep-ph/0408241, in which the authors studied that neutrinos could form "halos" around sufficiently large dark matter (and baryonic matter) gravitational potentials.
Although I find it interesting, I have a bit of a trouble understanding some parts of the paper. For example, apparently in their classical halo calculations, they say they do not consider classical galaxy-neutrino “bound states”, like the sun-earth one. But if they do not consider classical galaxy-neutrino gravitational "bound states" how can they study the gravitational clustering of neutrinos around cold dark matter and baryonic matter structures? I mean, gravitational clustering means that the neutrinos are being attracted by gravity thus forming a (gravitational) bound state with those structures, right?
Also, I have been told that neutrino halos likely have little angular momentum, just like other dark matter halo models. But although is likely that they have low angular momentum, is it at least physically possible that a rare neutrino halo may have a high angular momentum? Or since the neutrinos would be weakly bounded even a small amount of angular momentum could risk them being expelled from the halo? Also, even if they have low angular momentum, if we have a large enough neutrino halo, could the total angular momentum be large (as we would have a lot of mass in form of neutrino particles)?
