Analysis of the ESPRESSO QSO observations for the variability of the fine-structure constant

June 3 – 14, 2019

Several extensions of the Standard Physical Model predict a space-time variation of the fundamental physical constants. Absorption lines of intervening systems towards distant quasars are the most effective way to test the stability of the fine-structure constant or the proton-to-electron mass ratio. These tests require measurements of a tiny variation of the position of one or few lines with respect to other reference lines. Claims of variability have already been made but the signal, at the level of few ppm (part per million), is comparable to the value of possible instrumental systematics. ESPRESSO is a new high spectral resolution, ultra stable spectrograph, delivering precise radial velocity measurements in the optical wavelengths and these fundamental physics tests have been one of its scientific drivers. 27 VLT nights of the GTO are dedicated to collect spectra of a sample of 18 carefully selected, relatively bright and well studied QSOs to significantly improve current measurements of the constancy of the fine structure constant and break the 1 ppm precision. The project is aimed to gathering the people participating in the GTO ESPRESSO project to make a new data reduction of the first data collected in November 2018 and Spring 2019, with the purpose to characterize the instrument and evaluate precision and accuracy of the wavelength calibration. A first analysis of the data is also planned.

Project proponent:

  • Michael Murphy (Swinburne University of Technology, Melbourne)

List of participants:

  • Guido Cupani (INAF, Osservatorio Astronomico di Trieste)
  • Valentina D’Odorico (INAF, Osservatorio Astronomico di Trieste)
  • Catarina Leite (Istituto de Astrophysica e Ciencias do Espaco, University of Porto)
  • Michael Murphy (Swinburne University of Technology, Melbourne)
  • Paolo Molaro (INAF, Osservatorio Astronomico di Trieste)
  • Tobias Schmidt (INAF, Osservatorio Astronomico di Trieste)