Ana C. O. Leite
IA

Abstract
ESPRESSO is a high-resolution-ultra-stable spectrograph for ESO's Very Large Telescope, which started operations last year. ESPRESSO will allow to gather light simultaneously from the 4 individual Units of Telescope and measure the fainter objects with unprecedented resolution and stability.
One of the key science goals of the instrument is to test the stability of nature's fundamental couplings. Fine-structure constant and proton-to-electron ratio can be tested looking into metal absorption lines produced by the intervening clouds along the line of sight of quasars. These tests require measurements of a tiny variation of the position of a few lines with respect to other reference lines. There is a claim made by Webb et al 2012 of a variation of the fine-structure constant at the level of few parts per million, but this value is at the level of identified instrumental systematics. ESPRESSO design will allow to eliminate current known systematics and test the previously claimed variability, aiming to put constraints on fine-structure constant at the 1 ppm precision.
In this talk, I will describe the complexity of the methods used to measure fundamental constants using quasars and the current state of the field. Further, I will explore how ESPRESSO should be able to perform systematics free measurements, and some results from the first tests that were performed during commissioning.
I will end by showing examples of the impact that these improved measurements can have on Cosmology.

2019 May 28, 14:30

IA/U.Lisboa
Faculdade de Ciências da Universidade de Lisboa (C8.2.16)
Campo Grande, 1749-016 Lisboa