Can sterile neutrinos be the dark matter?
Sterile neutrinos are introduced to explain the observed neutrino masses. These particles can be of great cosmological and astrophysical significance. ~ keV, it can be the dark matter. Different production mechanisms result in “colder” or “warmer” DM.
Are neutrinos hot dark matter?
Neutrinos. An example of a hot dark matter particle is the neutrino. Neutrinos have very small masses, and do not take part in two of the four fundamental forces, the electromagnetic interaction and the strong interaction.
Why is it not likely that dark matter is made of 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. They would only interact with matter gravitationally, so they are known as sterile neutrinos.
How much of the dark matter could neutrinos be?
Given the constraints we have today, we can conclude that approximately 0.5% to 1.5% of the dark matter is made up of neutrinos. This isn’t insignificant; the light neutrinos in the Universe have about the same mass as all the stars in the Universe.
Could dark matter be right handed neutrinos?
The discovery of neutrino mass opened up another possibility: a right-handed neutrino. In particle physics, handedness is a quality that emerges from a particle’s mass and spin. As massless particles, neutrinos wouldn’t be able to change their handedness—but with mass, they can.
How hot are neutrinos?
But because they are very low-energy particles, the Big Bang neutrinos are also nearly impossible to find. Scientists estimate that the cosmic neutrino background has a temperature even colder than the cosmic microwave background, somewhere around minus 271 degrees Celsius.
Are axions dark matter?
With a mass above 10−11 times the electron mass, axions could account for dark matter, thus be both a dark-matter candidate and a solution to the strong CP problem.
What makes dark matter dark?
Dark matter is called dark because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect or emit electromagnetic radiation, and is therefore difficult to detect.
What is the difference between hot dark matter and cold dark matter?
Hot dark matter is dark matter made of particles traveling at or near the speed of light. Cold dark matter refers to dark matter made of slowly moving particles. Astronomers think most dark matter is cold dark matter as this kind of matter would allow for matter to clump together to form galaxies.