New dark matter production mechanism and the gravitational wave signals

The microscopic origin and production mechanism of dark matter (DM) remain central questions in cosmology and particle physics. While thermal freeze-out has long dominated DM model building, alternative non-thermal scenarios are gaining prominence. In this work, we explore novel production channels for heavy DM candidates, including pseudo-Nambu-Goldstone bosons (pNGBs), Q-balls, and filtered DM arising from early-universe phenomena such as primordial black hole (PBH) evaporation, superradiance, and first-order phase transitions (FOPTs). We demonstrate that these mechanisms naturally generate gravitational wave (GW) signals detectable by future observatories, such as LISA, TianQin, Taiji, and Cosmic Explorer. This multi-messenger approach offers a promising pathway to probe the origin and nature of DM beyond conventional paradigms.