Speaker
Description
Observations of gravitational waves (GWs) allow us to infer their locations and distances. Galaxies, on the other hand, have precise angular positions but no direct measurement of their distances -- only redshifts. The cross-correlation of GWs with galaxies is thus a very promising cosmological tool since it can lead to a direct measurement of the Hubble diagram $D_L(z)$. In this talk I will discuss two proposed approaches for this cross-correlation. The first one, dubbed line-of-sight dark sirens, is the more traditional one and relies on identifying candidate host galaxies for each GW. The second, named Peak Sirens, relies only on the statistical proximity of the dark sirens and galaxies (a general property of large-scale structures) and is model-independent. I will compare the power of each technique both in terms of precision and robustness to systematics. I show forecasts for run 5 of LIGO-Virgo-KAGRA, as well as for the third-generation observatories Einstein Telescope and Cosmic Explorer. Finally, I will show the first real-data results of the peak sirens method.
