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; ... (2021). Fundamental physics with ESPRESSO: Towards an accurate wavelength calibration for a precision test of the fine-structure constant. Astronomy and astrophysics, 646, A144. EDP Sciences 10.1051/0004-6361/202039345

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Observations of metal absorption systems in the spectra of distant quasars allow 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, 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, 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 24m/s. 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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences > Theoretical Astrophysics and Planetary Science (TAPS)
08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute
10 Strategic Research Centers > Center for Space and Habitability (CSH)
08 Faculty of Science > Physics Institute > NCCR PlanetS

UniBE Contributor:

Alibert, Yann Daniel Pierre, Broeg, Christopher

Subjects:

500 Science
500 Science > 520 Astronomy
500 Science > 530 Physics
600 Technology > 620 Engineering

ISSN:

0004-6361

Publisher:

EDP Sciences

Language:

English

Submitter:

Janine Jungo

Date Deposited:

28 Mar 2022 16:11

Last Modified:

05 Dec 2022 16:12

Publisher DOI:

10.1051/0004-6361/202039345

BORIS DOI:

10.48350/166501

URI:

https://boris.unibe.ch/id/eprint/166501

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