Newtonian calibrator tests during the Virgo O3 data taking

Abstract

Abstract The gravitational-wave detectors outputs from the LIGO and Virgo collaborations have been a source of scientific results of prime importance in various domains such as astrophysics, cosmology or fundamental physics. With the upgrades of the detectors and their improved sensitivities, new challenges are set for these instruments calibration. A calibration method based on the local variations of the Newtonian gravitational field could be the next absolute reference of calibration for the interferometers network. We report new tests of Newtonian calibrators (NCal) on the advanced Virgo detector performed during the LIGO–Virgo observing run O3. The NCal-induced strain on a mirror of the interferometer has been computed both using analytical calculations and numerical simulations with results in very good agreement. The strains given by the numerical model have been used to analyse the data of the NCals and have been compared to the reference method of calibration using photon radiation pressure. New methods to measure the NCal to mirror distance and the NCal offset with respect to the plane of the interferometer using two NCals are also presented. They are used to correct the NCal data which improves the agreement with the current advanced Virgo reference of calibration.