We do know the attributes of dark matter, and much of how it acts, so we know what physical properties dark matter must have, but no recognized matter has all the required qualities of dark matter. They only engage weakly with other matter and do not interact strongly with light, so they can be thought about a type of dark matter. Based on dark matter observations such as the clustering of galaxies, we know that cosmic dark matter must be primarily cold. Neutrinos might make up a small portion of dark matter, but most dark matter must be something else.
Due to the fact that neutrinos are so close to satisfying the properties of dark matter, some scientists have actually argued dark matter may be a yet undiscovered range understood as sterile neutrinos.
We do not understand what dark matter is. We do know the characteristics of dark matter, and much of how it behaves, so we know what physical residential or commercial properties dark matter should have, but no known matter has all the essential characteristics of dark matter. So were stumped.
The closest thing we have is neutrinos. They only connect weakly with other matter and do not connect strongly with light, so they can be considered a type of dark matter. The only issue is that the three understood varieties of neutrino all have exceptionally little masses. Because of this, they zip around the cosmos at almost the speed of light. This implies neutrinos are a type of “hot” dark matter, just as a hot gas is comprised of fast-moving particles. Based on dark matter observations such as the clustering of galaxies, we understand that cosmic dark matter should be primarily cold. Neutrinos might comprise a small portion of dark matter, but a lot of dark matter should be something else.
The helicity of anti-neutrinos and neutrinos. Credit: Universe Review
Due to the fact that neutrinos are so close to satisfying the residential or commercial properties of dark matter, some scientists have actually argued dark matter might be a yet undiscovered variety understood as sterilized neutrinos. Like other elementary particles, neutrinos have actually a particular called helicity. Basically, a neutrino can spin clockwise along its instructions of movement (left-handed helicity) or counter-clockwise along its motion (right-handed). Most particles can have either sort of helicity, however neutrinos are odd. We just see right-handed anti-neutrinos and left-handed neutrinos.
This means that if right-handed neutrinos exist, they do not connect with routine matter, only with gravity. And if they have a substantially larger mass than routine neutrinos, sterilized neutrinos would be “cold,” and might be the option to the dark matter issue.
The group inserts the time-projection chamber into the MicroBooNE cryostat. Credit: Reidar Hahn, Fermilab
Neutrinos were beamed into the MicroBooNE detector to see what types of interactions happened with regular matter. One possible service to this mystery is that sterilized neutrinos engaging with other neutrinos produce an excess of electrons in the observed events. The data guidelines out background photons with 95% confidence, and sterile neutrinos with 99% self-confidence.
Sterilized neutrinos might still exist, but their communicates need to be more subtle than models anticipate. There might also be some complicated interactions among routine neutrinos that are currently not considered in the basic model.
Reference: Abratenko, P., et al. “Search for Neutrino-Induced Neutral Current Delta Radiative Decay in MicroBooNE and a First Test of the MiniBooNE Low Energy Excess Under a Single-Photon Hypothesis.” arXiv preprint arXiv:2110.00409 (2021 ).
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