Speaker
Description
Cosmic acceleration may arise from modifications to gravity that become significant on large scales. In many scalar–tensor and effective-field-theory models, an evolving gravitational coupling changes the friction experienced by gravitational waves (GWs), causing their luminosity distance to differ from the electromagnetic prediction. In this talk, I will present constraints on dark-energy-related modified gravity using the latest GW catalog from the LIGO–Virgo–KAGRA O4 run. We test this effect with a hierarchical standard-siren analysis that jointly models cosmology and compact-binary population properties in associate with galaxy-catalog information. I will present constraints on some phenomenological parameterization based on scalar-tensor gravitational theories and higher-dimensional gravitational theories, as well as a general ($\Xi_0-n$) parametrization. While the resulting constraints remain consistent with general relativity, they demonstrate that GW distances provide an independent cosmological test of gravity across large distances and establish analysis requirements for future LVK catalogs and next-generation observatories.