Gravitational wave backgrounds, sources, data analysis in LVK and present/future challenges

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). However, the amplitude of this background is much lower than that of gravitational waves coming from mergers of binary black holes. Hence, a cross-correlation between data from different interferometers is performed to try to estimate the amplitude of the background, though the current sensitivity of the gravitational wave ground-based detectors is still not enough to make a detection. In this talk, I will give a brief summary on the GWB, its sources, the data analysis techniques we use in the LVK collaboration as well as which are the challenges we face. Furthermore, I will briefly comment on future challenges that will be encountered with third generation detectors.