The dark matter freeze out and beyond

Evidence of the existence of dark matter has been found due to deviations of gravitational motion of astronomical objects. We want to investigate the dark matter topic, which is constantly evolving due to the fast development of technology today. The thermal freeze out of dark matter has been proposed to be the production mechanism of DM in the Universe. We look into this production mechanism, and the properties of dark matter that follows from it. We derive the Boltzmann equation of the thermal freeze out approximately analytical, to study the thermodynamic properties of the freeze out. By the use of the Fortran-program DarkSUSY, a calculation program for DM properties, we calculate precise values of the same properties. By comparing observational values of dark matter with our derivations and calculations, we can learn about the non-gravitational properties of DM. We further introduce some dark matter particle candidates, the generic weakly interacting massive particle (WIMP), and the scalar singlet. The freeze out production mechanism has not been confirmed, because the particle candidates have not been detected. Due to this, we look further into alternative production mechanisms. The freeze in production mechanism of dark matter has been proposed, with the corresponding dark matter particle candidate FIMP (feebly interacting massive particle), and we look briefly into this