"Some recent results in gravitational-wave science"

The era of gravitational-wave astrophysics and cosmology has begun. We'll discuss some recent results, focusing on constraints that come from the population of gravitational-wave events. Topics will include the lower (between neutron stars and black holes) and the upper (due to pair-instability supernovae) mass gaps, standard siren cosmology, and recent events including GW190814 (with a secondary object that might be a neutron star or a black hole; we're not sure which) and GW190521 (with two black holes potentially in the pair-instability mass gap).