Up till now I have thought that Hawking radiation would be mostly photons, since the temperatures are typically small. However, a comment on another question (thanks to John Doty) suggested that we should also consider other species of low rest mass. So my question is: could Hawking radiation have a large contingent of neutrinos? And could there be any other species of low mass?
As I understand it, the $Z$ mass measurement rules out further generations of neutrinos in the standard model, but presumably not further particles which don't interact with $Z$. Again, as I understand it, dark matter is thought to be largely 'cold', which suggests that if it is particles then they have high not low mass. But could there be a significant contingent of low mass particles?
We don't need to consider neutrinos in thermal radiation from ordinary matter, because their interactions are so weak, so they are not produced in anything like the same quantities as photons. But gravity being universal, I wonder whether Hawking neutrino radiation might have similar power to Hawking electromagnetic radiation, at least for small black holes whose temperature is above a few thousand kelvin, if we take neutrino mass as $0.1$ eV. That would be interesting, but perhaps it is ruled out by some argument coming from electroweak theory?