Beyond standard sirens: Gravitational wave cosmology without electromagnetic counterparts

TALK RECORDING AVAILABLE AT: https://drive.google.com/file/d/1s1C2WeDhsshXjYU0Ez4RrrKcBahAGcgc/view?usp=share_link

Abstract:

The first seven years of direct gravitational wave detection have had a huge impact on astrophysics, cosmology and fundamental physics. Many of the developments in the latter two areas hinge crucially on the detection of the first standard siren, GW170817. However, this kind of event now seems to be incredibly rare. Will we still be able to answer our key questions about cosmology and the nature of gravity without many more standard sirens? In this talk I’ll introduce a set of alternative techniques designed to fill this gap. The first of these, known as Dark Sirens, substitutes the missing EM counterparts with a galaxy catalogue; I’ll explain this method in some detail, reviewing its challenges and promising early results. I’ll also talk about some other techniques to test gravity with GWs, which rely on i) multiband GW sources, and ii) modifications to gravitational waveforms themselves in the low-frequency regime.