Space-based gravitational-wave detectors can determine the thermal history of the early Universe

Abstract

It is shown that space-based gravitational-wave detectors such as DECIGO and/or the Big Bang Observer will provide us with invaluable information on the cosmic thermal history after inflation, and they will be able to determine the reheat temperature ${T}_{R}$ provided that it lies in the range preferred by the cosmological gravitino problem, ${T}_{R}\ensuremath{\sim}{10}^{5--9}\text{ }\text{ }\mathrm{GeV}$. Therefore it is strongly desired that they will be put into practice as soon as possible.