MeV sterile neutrinos in low reheating temperature cosmological scenarios

Abstract

It is commonly assumed that the cosmological and astrophysical bounds on the mixings ofsterile with active neutrinos are much more stringent than those obtained from laboratorymeasurements. We point out that in scenarios with a very low reheating temperature MeV at the end of (the last episode of) inflation or entropy creation, the abundance ofsterile neutrinos becomes greatly suppressed with respect to that obtained within thestandard framework. Thus, in this case cosmological bounds become much lessstringent than usually assumed, allowing sterile neutrinos to be ‘visible’ in futureexperiments. Here, we concentrate on massive (mostly sterile) neutrinos with massesms>1 MeVfor TRH≤ms.