A hidden self-interacting dark matter sector with first-order cosmological phase transition and gravitational wave

A dark scalar mediator can easily realize the self-interacting dark matter scenario and satisfy the constraint of the relic density of the dark matter. When the hidden sector is highly decoupled from the visible sector, the constraints from direct and indirect detections of dark matter are rather relaxed. The gravitational waves produced by the first-order phase transition resulted from this dark scalar mediator will be an important signature to probe such a dark sector. In this work, a generic quartic finite-temperature potential is used to induce a strong first-order phase transition. A joint analysis of the self-interacting dark matter, the relic density of the dark matter and the first-order phase transition show that the mass range of the dark scalar is about (4 X 10(-4) similar to 3) GeV. For the dark matter, when the temperature ratio xi between the hidden sector and the visible sector is larger than 0.1, its mass range is found to be (10 MeV-10 GeV). The produced gravitational waves are found to have a peak frequency of (10(-6)-10(-3)) Hz for a temperature ratio 0.1 < xi < 1, which may be detectable in future measurements.

Automated summary

A dark scalar mediator can realize self-interacting dark matter and meet the constraint of the relic density. When the hidden sector is decoupled from the visible sector, the constraints from direct and indirect detections of dark matter are relaxed. The gravitational waves resulted from the first-order phase transition caused by the dark scalar mediator can be used to probe the dark sector.