Implication of nano-Hertz stochastic gravitational wave on dynamical dark matter through a dark first-order phase transition

Abstract: For the first time, the expected stochastic gravitational wave background is probably discovered after observing the Hellings Downs correlation curve by several pulsar timing array (PTA) collaborations around the globe including NANOGrav, European PTA, Parkes PTA, and Chinese PTA. These new observations can help to explore or constrain the dark matter (DM) formation mechanisms in the early Universe. We study the implication of those results on the dynamical DM formation mechanisms through a dark first-order phase transition in the early Universe. Both the Q-ball DM and super-cool DM are investigated in the strong super-cooling dark phase transition scenario which may give an interpretation of the observed stochastic gravitational wave background.