No need to know: Astrophysics-agnostic spectral siren cosmology

Gravitational waveforms contain information about both the luminosity distance and redshift to their sources, making them clean probes of the expansion history of our universe, H(z). However, redshift information is completely degenerate with the masses of the objects that created the waveform, making it impossible to know the redshift of a single binary without knowledge of its masses. In this talk, we show how simultaneously inferring the mass distribution of gravitational wave sources along with cosmological parameters breaks this degeneracy. Additionally, we use a flexible, non-parametric model for the mass distribution to demonstrate that prior knowlege of the mass distribution's morphology is not necessary in order to preform this measurement. Non-parametric cosmological probes such as these will allow future ground-based gravitational wave detectors to make cosmological measurements to higher redshifts than any other instruments, with less systematic uncertainty.