Browsing by Subject "early universe phase transitions"

Gravitational waves predicted by the theory of general relativity are providing us with an opportunity to study cosmological processes well beyond the horizon for electromagnetic observations. One such process is a first-order phase transition as the universe cools down, which could generate gravitational waves observable in the millihertz range today. The upcoming Laser Interferometer Space Antenna (LISA) is a space-based gravitational wave observatory with peak sensitivity in the millihertz range, so it has the potential to observe a sufficiently strong phase transition signal. The LISA Consortium have developed the LISA simulation pipeline for the purposes of creating mock data, which can then be used to test data analysis methods in preparation for the real LISA data analysis. Our aim is to first test the simulation pipeline by injecting a phase transition signal, with added instrument noises and galactic binary confusion noise, which we expect to be present in the real observations as well. Second, we will attempt to recover the injected signal to see whether it is detectable based on the deviance information criterion (DIC). We will do this for 25 different parameter combinations in order to chart the detectability of signals from different phase transition scenarios. Our results show better detectability for phase transition signals with higher amplitudes and frequencies centered around the mHz range, which is where the expected peak sensitivity of LISA lies. The confusion noise appears to be less of a distraction to our observations than the instrument noises, which set limits in the extremes of the LISA frequency range.