Dark energy constraints from ESPRESSO tests of the stability of fundamental couplings

TL;DR

This paper discusses how ESPRESSO's high-precision spectroscopic measurements of fundamental couplings can significantly improve constraints on dark energy properties, extending the redshift range and complementing supernova surveys.

Contribution

It introduces a novel approach to constrain dark energy by using ESPRESSO's stability tests of fundamental couplings, enhancing the redshift coverage for dark energy studies.

Findings

Improved dark energy equation of state reconstructions with extended redshift data.

Quantified potential enhancements from future ELT-HIRES measurements.

Forecasted dark energy constraints from ESPRESSO's fundamental coupling tests.

Abstract

ESPRESSO is a high-resolution-ultra-stable spectrograph for the VLT, whose commissioning will start in 2017. One of its key science goals is to test the stability of nature's fundamental couplings with unprecedented accuracy and control of possible systematics. A total of 27 nights of the ESPRESSO Consortium's guaranteed time observations (GTO) will be spent in testing the stability of the fine-structure constant and other fundamental couplings. A set of 14 priority optimal targets have been selected for the GTO period. Here we briefly discuss the criteria underlying this selection and describe the selected targets, and then present detailed forecasts of the impact of these measurements on fundamental physics and cosmology, focusing on dark energy constraints and using future supernova type Ia surveys as a comparison point. We show how canonical reconstructions of the dark energy equation of state are improved by the extended redshift range enabled by these spectroscopic measurements, and also quantify additional improvements foreseen for a future ELT-HIRES instrument.