Thermally modified sterile neutrino portal dark matter and gravitational waves from phase transition: The Freeze-in case

Understand

We consider the thermal effects into the evaluation of the dark matter production process.

• With the assistance of the right handed neutrinos, the freeze-in massive particle dark matter production history can be modified by the two-step phase transitions.
• The kinematic of decay/inverse decay or annihilation processes can be affected by the finite temperature effects as the Universe cools down.
• The history of the symmetry respected by the model can be revealed by the DM relic abundance evolution processes.