Visible Sterile Neutrinos as the Earliest Relic Probes of Cosmology

Understand

A laboratory detection of a sterile neutrino could provide the first indication of the evolution of the Universe before Big-Bang Nucleosynthesis (BBN), an epoch yet untested.

• Such "visible" sterile neutrinos are observable in upcoming experiments such as KATRIN/TRISTAN and HUNTER in the keV mass range and PTOLEMY and others in the eV mass range.
• A set of standard assumptions is typically made about cosmology before the temperature of the Universe was 5 MeV.
• However, non-standard pre-BBN cosmologies based on alternative assumptions could arise in motivated theoretical models and are equally in agreement with all existing data.