Ram-pressure is an important driver for the evolution of galaxies infalling clusters, transforming star-forming galaxies into passively evolving systems and forming long tails of stripped material in the process. In this seminar, I present studies of different aspects of this evolution and discuss how they fit together to form a complete picture. Using high resolution HST photometry, we are able to model the star-formation histories (SFHs) of star-forming regions in the tails of six z~0.04 galaxies undergoing extreme ram-pressure (Jellyfish galaxies). We find that the median mass-weighted ages of these regions are ~27 Myrs when the detection is made in narrow-band Hα and ~39 Myrs when the detection is made in the ultraviolet. Regions found further away from the host galaxy are on average younger, less massive and less obscured by dust. The stellar masses of the larger star-forming regions in our sample are consistent with the ones of globular clusters, but their stellar mass surface densities are lower by 2 dex, and their properties are more consistent with the population of dwarf galaxies in clusters. In clusters beyond the local universe (z~0.4), we use MUSE data cubes to identify galaxies undergoing ram-pressure, as well as recently quenched galaxies (post-starbursts). We find that jellyfish galaxies in these clusters have enhanced star-formation rates, and their gas-phase metallicity generally drops along the tail, which suggests mixing with the intracluster medium. The spatially-resolved SFHs of post-starburst galaxies in this sample shows that they quenched their star-formation between 100 and 800 Myrs ago, with at least ~10% (and up to more than 50%) of the stellar mass being assembled in the past 1.5 Gyr. Most of them have quenched their star-formation from the outside-in or show a side-to-side/irregular pattern, both consistent with quenching by ram-pressure stripping. Only three objects show an inside-out quenching pattern, all of which are at the high-mass end of our sample. All of these features are consistent with post-starbursts being the remnants of jellyfish galaxies.
Alessandro IGNESTI
