Introduction

• Benoit Mours (IPHC Strasbourg)

Room: Mondrian

Improving gravitational-wave detectors calibration for accurate and precise physics

• Dimitri Estevez (CNRS)

Room: Mondrian As the sensitivies of the gravitational-wave detectors from the LIGO-Virgo-KAGRA collaboration improve, calibration of the detectors outputs is becoming more and more important since it may impact scientific results, like the Hubble constant measurement for which a prompt identification of the sources is important. I will present the absolute calibration method using radiation pressure I implemented on Virgo, which has been used as calibration reference during the third observing run (O3). This method being used by all the detectors of the LIGO-Virgo collaboration, I performed the first relative calibration of the detectors network. Then, I will focus on a new calibration method using variations of the local gravitational field that we are developing to reach a sub-percent accuracy on the reconstructed gravitational-wave signals. Eventually, I will conclude on the synergy of both systems for future observing runs and for the third generation detectors.

Enabling multi-messenger cosmology with the LIGO-Virgo alert system

• Sarah ANTIER (APC)

Room: Mondrian In 2017, the joint discovery of gravitational waves and electromagnetic counterparts from a binary neutron star merger offered a detailed view of this event, with implications for cosmology, with an independent estimate of the Hubble constant. However, no new, confirmed multi-messenger detection have been made to date. My talk will focus on the enrichment of gravitational wave alerts, to increase their accuracy, and build a well characterized multi-messenger sample. It will provide a better modeling on the binary neutron star mergers, with a better estimation of the systematic errors. It will advance precision cosmology using GWs as bright sirens.

Entering the era of gravitational waves precision astrophysics: signal modelling and tests of new physics

• Leïla Haegel (Laboratoire APC, Université Paris-Diderot / CNRS)

Room: Mondrian The discovery of gravitational waves (GW) in 2015 opened an unprecedented channel to search for new physics. Measuring the dispersion of GW during their propagation enables to probe a large set of alternative theories of gravitation, of which I will describe the current constraints as well as the ones in development. Those analyses take place in the framework of the Standard Model Extension, an effective field theory enable to search for new phenomena independently of specific models but offering connexions with proposed new theories. Such deviations are however expected to be very small, and require a very accurate modelling of the gravitational waves signal to avoid false detections. I will review the new methods recently applied to generate very precise GW templates adapted for the future of GW analyses.