Speaker: Simone Bavera (Geneva U.)
Title: Unravelling the origins of merging stellar-mass binary black holes
Abstract: 
The second LIGO-Virgo catalogue of gravitational-wave transients (GWTC-2) has more than quadrupled the observational sample of binary black holes (BBH). Increasingly accurate theoretical models are required to compare to the observed sample and disentangle contributions from multiple channels. I will present the latest state-of-the-art BBH models of isolated binary evolution, which involve stable mass transfer, common envelope and chemical homogenous evolution. These population synthesis models are the first in the literature to use detailed stellar and binary simulations to accurately model the tidal spin-up of the BH's progenitors and the collapse of the star's profile. I will then review the analysis results on GWTC-2 using these and a selection of models from dynamical formation. This analysis shows that a mixture of channels is strongly preferred over any single channel dominating the detected population. Moreover, GWTC-2 also contains the detection of the first BH neutron star system. To date, no electromagnetic (EM) counterpart was reported to be observed with the event. The lack of an EM  counterpart is consistent with our latest models that include updated 1D core-collapse prescriptions. Finally, I will present new results which show that the formation of highly spinning BBH mergers are associated with long-duration gamma ray burst (LGRB). Because highly spinning BBHs have a short merging timescale, LGRB observations can be used to probe them throughout cosmic time, outside current gravitational waves detectors' horizons.