STUDYING THE BAR PATTERN SPEED EVOLUTION ACROSS COSMIC TIME WITH EUCLID

The bar pattern speed is a key parameter characterising the dynamical state of galactic bars. Theoretical arguments and numerical simulations suggest that its time evolution is closely connected to dynamical friction and angular momentum exchange with the surrounding dark matter halo in which the bar forms. Observational measurements of bar pattern speeds as a function of redshift therefore provide important constraints on models of galaxy formation and the secular evolution of barred galaxies. In this thesis, we aim to investigate the evolution of bar pattern speeds with redshift by exploiting morphological measurements of low-inclination ringed galaxies from the Euclid Quick Data Release 1. Deep neural networks are used to identify the sample galaxies out to a redshift of 1, corresponding to the last 7 Gyr. Their optical images are analysed to measure the ratio between the deprojected outer ring radius and the bar size, a quantity commonly used as a proxy for the dark matter fraction within the bar region. Dividing the sample into redshift bins, the measurements show no significant trend in the distribution of the bar pattern speed with redshift. This provides the first statistically significant evidence that the bar pattern speed has not undergone significant evolution over the last ∼7 Gyr.