Two-peak gravitational wave spectra from supercooled two-field phase transitions

Abstract

We study the gravitational wave (GW) spectrum generated by supercooled first-order phase transitions in two-field conformal models. We construct three representative toy models that capture the essential features of these models, derive analytical criteria for the existence of two-step transitions, and show how the two-field dynamics generate a genuine two-peak GW spectrum. We identify regions of parameter space in which two-peak GW spectra are observable at LISA and the Einstein Telescope. By way of illustration, we apply our analysis to a realistic conformal dark SU(3) model.