cosmic neutrino background

See also cosmic neutrino background and extragalactic background light.

(There is quite likely a correspondingly large number of neutrinos called the cosmic neutrino background.)

Cosmic neutrino background (CνB)

The cosmic neutrino background (CNB, CνB) is the universe's background particle radiation composed of neutrinos.

Similarly, the surface of the cosmic neutrino background, if it could be observed, would mark when neutrinos decoupled and began to stream freely through the rest of the matter in the universe.

This cosmic neutrino background, while unlikely to ever be observed in detail since the neutrino energies are very low, is analogous to the cosmic microwave background that was emitted much later.

The data included new evidence for the cosmic neutrino background, evidence that it took over half a billion years for the first stars to reionize the universe, and new constraints on cosmic inflation.

While neutrino decoupling can not be observed directly, it is expected to have left behind a cosmic neutrino background, analogous to the cosmic microwave background radiation of visible light which was emitted at a much later epoch.

Analogous to the decoupling of photons, neutrinos decoupled when the rate of weak interactions between neutrinos and other forms of matter dropped below the rate of expansion of the universe, which produced a cosmic neutrino background.

He studied the cosmic neutrino background needed to interpret the solar neutrino experiment of his friend and collaborator Raymond Davis, Jr. at Homestake Mine in South Dakota by using the overlaying soil and rock as a filter to remove other types of radiation.

Less than 1% of the current contents of the universe is in neutrinos, but WMAP's measurements have found, for the first time in 2008, that the data prefers the existence of a cosmic neutrino background with an effective number of neutrino species of 3.26 0.35.

In the universe today, matter is mainly in forms of galaxies and dark matter, while the radiation is the cosmic microwave background radiation, the cosmic neutrino background (if the neutrino rest mass is high enough then the latter is formally matter), and finally, mostly in the form of dark energy.