Browsing by Author "Häkkinen, Jenni"

Gravitational waves from cosmological phase transitions are a promising probe of the early universe. Many theories beyond the Standard Model predict the early universe to have undergone a cosmological first-order phase transition at the electroweak scale. This transition would have produced gravitational waves potentially detectable with the future space-based detector Laser Interferometer Space Antenna (LISA). We study the gravitational wave power spectrum generated by sound waves, which are a dominant source of gravitational waves from first-order phase transitions. We compare two methods for calculating the sound wave power spectrum: a simulation-motivated broken power-law fit of the shape of the spectrum, and a wider theoretical framework called the Sound Shell Model, which includes hydrodynamic calculations of the phase transition. We present an implementation of the Sound Shell Model into the PTPlot tool, which is currently based on the broken power-law fit. With PTPlot, we calculate the signal-to-noise ratios of LISA for the sound wave power spectrum of each method. The signal-to-noise ratio allows us to estimate the detectability of gravitational wave signals with LISA. We analyse how the detectability of certain particle physics models changes between the two different methods. Our results show that the Sound Shell Model has a potentially significant impact on the signal-to-noise ratio predictions, but it does not uniformly improve or worsen the detectability of the gravitational wave signals compared to the broken power law. The code implementation is overall successful and lays the foundation for an updated release of PTPlot and future work within this topic.