Unraveling Freeze-in Dark matter through the echoes of gravitational waves

Abstract

In the quest to unravel the dark sector, feebly interacting freeze-in dark matter presents an intriguing possibility, plausibly explaining the consistent null results from various dark matter experiments. We propose a unique imprint in the form of gravitational waves generated during the freeze-in production of dark matter from heavy particle decay in the early universe. This characteristic gravitational wave signature can serve as a powerful probe for freeze-in dark matter. Our study indicates that future high-frequency gravitational wave experiments can detect these waves, offering a novel avenue to critically test the underlying conditions and requirements of this dark matter paradigm, which typically lie beyond the reach of current and planned dark matter detection experiments.

This version has been accepted at PRD Letters. Supplementary material has been added, and some parts of the main text have been relocated there. 7+3 pages, 3+2 figures, 1 table