Fundamental physics with ESPRESSO: Towards an accurate wavelength calibration for a precision test of the fine-structure constant

Schmidt, Tobias M.; Molaro, Paolo; Murphy, Michael T.; Lovis, Christophe; Cupani, Guido; Cristiani, Stefano; Pepe, Francesco A.; Rebolo, Rafael; Santos, Nuno C.; Abreu, Manuel; Adibekyan, Vardan; Alibert, Yann; Aliverti, Matteo; Allart, Romain; Allende Prieto, Carlos; Alves, David; Baldini, Veronica; Broeg, Christopher; Cabral, Alexandre; Calderone, Giorgio; Cirami, Roberto; Coelho, João; Coretti, Igor; D'Odorico, Valentina; Di Marcantonio, Paolo; Ehrenreich, David; Figueira, Pedro; Genoni, Matteo; Génova Santos, Ricardo; González Hernández, Jonay I.; Kerber, Florian; Landoni, Marco; Leite, Ana C. O.; Lizon, Jean-Louis; Lo Curto, Gaspare; Manescau, Antonio; Martins, Carlos J. A. P.; Megévand, Denis; Mehner, Andrea; Micela, Giuseppina; Modigliani, Andrea; Monteiro, Manuel; Monteiro, Mario J. P. F. G.; Mueller, Eric; Nunes, Nelson J.; Oggioni, Luca; Oliveira, António; Pariani, Giorgio; Pasquini, Luca; Redaelli, Edoardo; Riva, Marco; Santos, Pedro; Sosnowska, Danuta; Sousa, Sérgio G.; Sozzetti, Alessandro; Suárez Mascareño, Alejandro; Udry, Stéphane; Zapatero Osorio, Maria-Rosa; Zerbi, Filippo
Bibliographical reference

Astronomy and Astrophysics

Advertised on:
2
2021
Description
Observations of metal absorption systems in the spectra of distant quasars allow one to constrain a possible variation of the fine-structure constant throughout the history of the Universe. Such a test poses utmost demands on the wavelength accuracy and previous studies were limited by systematics in the spectrograph wavelength calibration. A substantial advance in the field is therefore expected from the new ultra-stable high-resolution spectrograph ESPRESSO, which was recently installed at the VLT. In preparation of the fundamental physics related part of the ESPRESSO GTO program, we present a thorough assessment of the ESPRESSO wavelength accuracy and identify possible systematics at each of the different steps involved in the wavelength calibration process. Most importantly, we compare the default wavelength solution, which is based on the combination of Thorium-Argon arc lamp spectra and a Fabry-Pérot interferometer, to the fully independent calibration obtained from a laser frequency comb. We find wavelength-dependent discrepancies of up to 24 m s-1. This substantially exceeds the photon noise and highlights the presence of different sources of systematics, which we characterize in detail as part of this study. Nevertheless, our study demonstrates the outstanding accuracy of ESPRESSO with respect to previously used spectrographs and we show that constraints of a relative change of the fine-structure constant at the 10-6 level can be obtained with ESPRESSO without being limited by wavelength calibration systematics.
Related projects
Full-sky map showing the spatial distribution of the primary anisotropies of the Cosmic Microwave Background (generated 380,000 years after the Big Bang) derived from observations of the Planck satellite
Anisotropy of the Cosmic Microwave Background

The general goal of this project is to determine and characterize the spatial and spectral variations in the temperature and polarisation of the Cosmic Microwave Background in angular scales from several arcminutes to several degrees. The primordial matter density fluctuations which originated the structure in the matter distribution of the present

Rafael
Rebolo López
Discovery of a system of super-Earths orbiting the star HD 176986 with about 5.7 and 9.2 Earth masses.
Very Low Mass Stars, Brown Dwarfs and Planets

Our goal is to study the processes that lead to the formation of low mass stars, brown dwarfs and planets and to characterize the physical properties of these objects in various evolutionary stages. Low mass stars and brown dwarfs are likely the most numerous type of objects in our Galaxy but due to their low intrinsic luminosity they are not so

Rafael
Rebolo López
spectrum of mercury lamp
Chemical Abundances in Stars

Stellar spectroscopy allows us to determine the properties and chemical compositions of stars. From this information for stars of different ages in the Milky Way, it is possible to reconstruct the chemical evolution of the Galaxy, as well as the origin of the elements heavier than boron, created mainly in stellar interiors. It is also possible to

Carlos
Allende Prieto