Cosmology in light of the LIGO and Virgo gravitational-wave detections

11.12.2020 11:30 – 12:30

Since the detection of the binary neutron star merger GW170817, gravitational waves (GWs) are rapidly entering in the field of cosmology. In this seminar I will review and discuss results and methodologies for inferring cosmological parameters using GW observations.

I will start by discussing the GW-based measurement of the Hubble constant from LIGO-Virgo events with and without electromagnetic counterparts. Then I will discuss the forecast on the Hubble constant estimation for future LIGO and Virgo observing runs, and describe the main sources of uncertainties and possible systematics for future GW-based Hubble constant measurements. For different detector network configurations, we will discuss one of the most significant limiting factors for GW-based cosmological inference, namely the luminosity distance-binary inclination degeneracy, as well as some possible solutions to break this degeneracy.

In the second part of the talk I will discuss how GWs can be used to probe deviations from General Relativity (GR) on cosmological scales. In particular we will focus on a modified GW friction term and a modified dispersion relation, while at the same time leaving the Hubble constant as a free parameter. Using a statistical method able to combine measurements of GWs as well as their electromagnetic counterpart and hosting galaxy, we will present novel constraints on the Hubble constant and the GW friction and dispersion terms. I will show that it is fundamental to consider jointly the measurements of these 3 parameters in order to avoid a biased measurement of one of the three. Finally I will present the results from GW170817 and GW190521, leading to updated and tighter upper-limits on GR modifications.

Lieu

Bâtiment: Ecole de Physique

entrée libre