Observational prospects for phase transitions at LISA: Fisher matrix analysis

Understand

A first order phase transition at the electroweak scale would lead to the production of gravitational waves that may be observable at upcoming space-based gravitational wave (GW) detectors such as LISA (Laser Interferometer Space Antenna).

• As the Standard Model has no phase transition, LISA can be used to search for new physics by searching for a stochastic gravitational wave background.
• In this work we investigate LISA's sensitivity to the thermodynamic parameters encoded in the stochastic background produced by a phase transition, using the sound shell model to characterise the gravitational wave power spectrum, and the Fisher matrix to estimate uncertainties.
• We explore a parameter space with transition strengths $\alpha < 0.5$ and phase boundary speeds $0.4 < v_\text{w} < 0.9$, for transitions nucleating at $T_{\text{N}} = 100$ GeV, with mean bubble spacings $0.1$ and $0.01$ of the Hubble length, and sound speed $c/\sqrt{3}$.