Implications for first-order supercooled cosmological phase transitions from the third LIGO-Virgo observing run and pre-O4 data quality techniques assessment

Gravitational waves are not just important probes of massive asymmetric astrophysical bodies, but they can also probe models Beyond the Standard Model in the very early Universe. These cosmological models, alongside the contribution from a large number of unresolved astrophysical objects such as binary neutron stars and black holes, are believed to source a background of gravitational waves (GWB). In this talk, I will give a brief summary on the GWB, its sources and the data analysis techniques we use in the Ligo-Virgo-Kagra (LVK) collaboration. I will then proceed to discuss the constraints we have set on the normalised energy density in GWs of one of the sources of this GWB, supercooled first-order phase transitions, using data from Advanced LIGO and Virgo's first, second and third observing runs. Furthermore, I will comment on some of the preparatory work for O4 carried out to assess the effect that some data quality techniques have in GWB searches.