Speaker
Description
Since the LIGO-Virgo-KAGRA gravitational wave (GW) detection from binary systems, GWs have become one of the most promising probes of cosmology and fundamental physics. The GW agenda is complemented by Pulsar Timing Arrays (PTA) probing the nHz frequency band, such as the European PTA (EPTA) and NANOGrav, both recently reporting a 3sigma evidence for a GW background. A next major step in that agenda is the Laser Interferometer Space Antenna (LISA), commissioned by ESA with NASA as a junior partner, and expected to be launched in the next decade. The detection of a stochastic GW background (SGWB) from interferometers or PTAs would offer an exciting look into the very early Universe, revealing fundamental physics on cosmological scales never probed before. This talk will focus on first-order phase transitions (PTs), one of the main mechanisms capable of sourcing SGWBs in the early Universe. I will present the Higgsless approach to simulate the plasma dynamics and to predict the stochastic GW spectrum from PTs. I will explain how the Higgsless simulations can produce fully nonlinear results and extend the current predictions to strong PTs, one of the most exciting scenarios to be explored by LISA and PTAs.