Stochastic Gravitational Waves

Abstract

In particle physics models of Grand Unified Theories (GUTs), we have a series of symmetry breaking in the early universe. For example we may have the symmetry breaking chain $$SO(10)\rightarrow SU(4)_c \times SU(2)_L \times SU(2)_R \rightarrow SU(3)\times SU(2)\times U(1)_Y $$ . There are two sources of gravitational waves. First, there is energy released in First Order Phase Transitions in the form of gravitational waves, whose characteristic frequency in the present universe depends on the temperature of the phase transition. Second, the symmetry breakings produce topological defects like monopoles, cosmic strings and domain walls which can produce gravitational waves. We study these sources of stochastic gravitational waves with the aim of predicting signals of this phenomenon for PTA, LISA and LIGO/VIRGO/KAGRA observations.