Ask Astro: Are neutrinos dark matter?

Richard Goering 

Neutrinos as physicists perceive them can not represent dark matter. The Commonplace Mannequin explains how the fundamental constructing blocks — basic particles — and three of the 4 recognized forces created the universe. Elementary particles are subatomic particles that don’t include some other particle; electrons are an instance, and so are neutrinos.

What guidelines neutrinos out of the operating for dark matter is that within the Commonplace Mannequin, they’re thought-about “sizzling” particles, which means they journey at speeds near the velocity of sunshine. For a particle to represent dark matter, it should be “chilly,” or journey slowly in comparison with gentle.

The key function dark matter performed within the formation of the universe was to clump itself up into giant plenty, whose gravity then attracted common matter, forming the large-scale buildings of the universe. If dark matter have been sizzling, the particles would have been shifting too quick to create these clumps, which means there can be no galaxies (a minimum of, not on the scales we observe them). We nonetheless observe these dark matter clumps, or dark matter halos, surrounding galaxies.

One other side of neutrinos that guidelines them out as dark matter candidates is that they aren’t really invisible — a minimum of, not in the way in which that physicists outline it. When a scientist refers to an invisible particle, it normally means a collision with one other particle has by no means been noticed. However researchers have seen neutrinos work together with different particles via the weak drive.

Hopefully dark matter isn’t totally invisible; in any other case we may by no means detect it instantly by “seeing” it. And since dark matter has been confirmed to work together gravitationally, astronomers and particle physicists are hopeful that it has some extremely suppressed interactions but to be seen.

Kaliroe Pappas