Direct measurement of the bar pattern speed in strongly and weakly barred galaxies

Bars are common in the local Universe across a wide range of galaxy morphologies, luminosities, and environments. The photometric, kinematic, and dynamical properties of bars depend on the formation and evolution process including the exchange of angular momentum with the other components. Their formation can be either induced by internal instabilities giving rise to a fast rotating bars slowing down with time, or by tidal interactions triggering slowly rotating bars. The measurement of the bar pattern speed allows to infer information about the mass distribution and the formation process of barred galaxies. In this thesis we aim at increasing the direct measurements of the bar pattern speed in strongly and weakly barred galaxies by applying the Tremaine-Weinberg method (TW) to integral-field spectroscopic data and at exploring the relations between the properties of bars and their host galaxies. We present a TW analysis of NGC4264, a barred lenticular galaxy in the region of the Virgo Cluster undergoing a tidal interaction with one neighbour. Analysing the surface photometry from SDSS i- and g-band images and the stellar kinematics from the integral-field spectroscopy performed with MUSE, we characterise the bar by measuring the radius, strength and pattern speed. We derive the circular velocity of the galaxy by correcting the stellar streaming velocity for asymmetric drift and calculate the bar rotation rate. NGC 4264 hosts a strong and large bar which is rotating fast. The measurement of the bar rotation rate allows us to infer that the formation of the bar of NGC4264 is due to internal processes and not triggered by the interaction. We investigate the formation process of weak bars. We select a sample of 29 nearby weakly barred galaxies, spanning a wide range of morphologies and luminosities. Combining our analysis with previous studies, we compare the properties of weak and strong bars. We measure the bar radius and strength from SDSS r-band images and bar pattern speed from the stellar kinematics obtained by CALIFA. 45 per cent of the visually-classified as weakly barred galaxies turn out not to host an actual bar component. The bar pattern speed is derived for 16 objects, including two ultrafast bars. With a quantitative criterion to differentiate weak and strong bars, we find that weakly barred galaxies host shorter bars and corotation radii than the strongly barred ones. Weak and strong bars have similar bar pattern speeds and rotation rates, which are all consistent with being fast. No difference is observed between the bulge prominence, whereas nearly all the weak bars reside in the disc inner parts, contrary to strong bars. We exclude that the bar weakening is only related to the bulge prominence and that the formation of weak bars is triggered by interactions. We suggest that weak bars may be evolved systems exchanging less angular momentum than strong bars. We revisit the relations between the properties of bars and their host galaxies. We collect 100 galaxies with a direct measurement of bar pattern speed. We consider the length, strength, pattern speed, corotation radius, and rotation rate of the bar as well as the Hubble type and absolute magnitude of the host galaxy. We also derive the bulge-to-total luminosity ratio for a subsample of galaxies. We limit our analysis to the 75 galaxies with a small relative error on the bar pattern speed and not hosting an ultrafast bar. We confirm earlier findings and we find that stronger bars rotate slower as predicted for the exchange of angular momentum during evolution. This result together with the fact that we observe stronger bars in bulge-dominated galaxies is in agreement with a scenario of downsizing in bar formation and co-evolution of bars and bulges if more massive galaxies formed earlier their bars and had sufficient time to slow down, grow in length, and in corotation. Finally, we discuss open issues and outline a few ideas for future investigations.