Antineutrinos Candidates for Dark Matter?

[endoftimes]

WIkipedia says antineutrinos are candidates for dark matter. What does this mean? How is it a candidate, and how could an antiparticle even exist in large quantities in the universe? Or is it only meant to be a small piece of problem?

 

[Chalnoth]

What Wikipedia page is this? Because it isn't correct.

Anti-neutrinos are just the anti-matter partner of neutrinos. There were a large number of neutrinos and anti-neutrinos produced in the early universe (essentially equal numbers of each), but their total mass is much too small to explain dark matter. In particular, their velocities are too high to explain the formation of structure in the early universe.

What might be a candidate is a "sterile neutrino", which is a hypothetical type of neutrino that doesn't interact with normal matter as easily as the three known species of neutrino. This sterile neutrino would have to be far more massive than the known neutrino species to account for observations.

 

[endoftimes]

What Wikipedia page is this? Because it isn't correct.

Anti-neutrinos are just the anti-matter partner of neutrinos. There were a large number of neutrinos and anti-neutrinos produced in the early universe (essentially equal numbers of each), but their total mass is much too small to explain dark matter. In particular, their velocities are too high to explain the formation of structure in the early universe.

What might be a candidate is a "sterile neutrino", which is a hypothetical type of neutrino that doesn't interact with normal matter as easily as the three known species of neutrino. This sterile neutrino would have to be far more massive than the known neutrino species to account for observations.

You know what, you are right. I was reading the page for neutrino wrong. I mistook the two words. It does say that neutrinos are candidates right here: https://en.wikipedia.org/wiki/Neutrino

 

[Chalnoth]

I see. That page does a good job of explaining why neutrinos don't work as dark matter particles, though its language is perhaps a bit more uncertain than I think is warranted.

 

[nikkkom]

WIkipedia says antineutrinos are candidates for dark matter.

In some sense of the term, neutrinos ARE (one kind of) dark matter particles: they are very weakly interacting with all other particles.

The problem is that neutrinos are too "hot": their average velocities are way too large, they can't be responsible for galaxy formation.

It is expected that there are some other, yet undiscovered DM particles with much lower velocities.

 

[Chronos]

Neutrinos are the low hanging fruit on the dark matter tree, but, have too little mass to be of much cosmological consequence. Sterile neutrinos might fill another gap, but, it appears the tree roots grow deeperr than that. I expect by the time we account for the majority of dark matter, we will have a complex mix of particles to add to the standard model

 

[Chalnoth]

Neutrinos are the low hanging fruit on the dark matter tree, but, have too little mass to be of much cosmological consequence. Sterile neutrinos might fill another gap, but, it appears the tree roots grow deeperr than that. I expect by the time we account for the majority of dark matter, we will have a complex mix of particles to add to the standard model

It's actually pretty difficult to get multiple different components of dark matter where one doesn't completely dominate over the others. Even very small changes in mass or how much they interact can lead to very large differences of abundance. So the best bet is that a single type of particle makes up the vast majority of dark matter.

For example, I'm pretty sure that in supersymmetry, only the lightest particle without electric charge is stable (the others would decay into the lighter particles).