Table of Contents
Can dark matter be neutrinos?
Neutrinos are a form of dark matter, because they have mass, and weakly interact with light. But neutrinos have such a small mass and high energy that they move through the universe at nearly the speed of light. For this reason, they are known as hot dark matter.
Why is it not likely that dark matter is made of neutrinos?
The reason they can only be hot dark matter is because it is assumed that in the early hot, dense universe, the neutrinos would have been in thermal equilibrium with the hot ordinary matter at that time.
Is the electron neutrino a realistic dark matter candidate?
At first glance, neutrinos are the perfect dark matter candidate. We know that there are leftover photons from the Big Bang, and very recently we’ve also detected indirect evidence that there are leftover neutrinos as well. Unlike the photons, which are massless, it’s possible that neutrinos have a non-zero mass.
What is an axion like particle?
Axion-like particles (ALPs) are pseudo-scalar particles. They are generally very light, very weakly interacting and have a coupling to electromagnetism. They are abundant in string theory and are also predicted in many other BSM models.
What would happen if neutrinos were dark matter?
So if neutrinos were dark matter they would be traveling 4\% the speed of light. Unfortunately, dark matter needs to be less than 300 km/s on average. The way we know this is that fast dark matter disrupts structure formation and washes it out. So galaxies wouldn’t have formed the way that they did.
Can neutrinos be that Big?
Unfortunately, there are two big problems with having light neutrinos that are that massive. When we look in detail, the idea of massive neutrinos is insufficient to make up 100\% of the dark matter.
Do we know how much dark matter there is around US?
No. Neutrinos haven’t been viable dark matter since the 1980s. We know how much dark matter there is our galaxy. Around us the mass density of matter (mass per unit volume) is and . We know that the three neutrinos have a mass less than . Additionally, we know that neutrinos are fermions.
What is the solar neutrino problem?
To explain the solar neutrino problem, one theory is that neutrinos undergo oscillations. Simply put, neutrinos come in different flavors and the probability that a neutrino is a particular flavor can change as the particle propagates.