2023/09/01 by Moretti, Alessia, Serra, Paolo, Bacchini, Cecilia +8 · 1 citation
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2309.00449
Cluster galaxies are affected by the surrounding environment, which influences, in particular, their gas, stellar content and morphology. In particular, the ram-pressure exerted by the intracluster medium promotes the formation of multi-phase tails of stripped gas detectable both at optical wavelengths and in the sub-mm and radio regimes, tracing the cold molecular and atomic gas components, respectively. In this work we analyze a sample of sixteen galaxies belonging to clusters at redshift ∼ 0.05 showing evidence of an asymmetric HI morphology (based on MeerKAT observations) with and without a star forming tail. To this sample we add three galaxies with evidence of a star forming tail and no HI detection. Here we present the galaxies \rm H2 gas content from APEX observations of the CO(2-1) emission. We find that in most galaxies with a star forming tail the \rm H2 global content is enhanced with respect to undisturbed field galaxies with similar stellar masses, suggesting an evolutionary path driven by the ram-pressure stripping. As galaxies enter into the clusters their HI is displaced but also partially converted into \rm H2, so that they are \rm H2 enriched when they pass close to the pericenter, i. e. when they develop the star forming tails that are visible in UV/B broad bands and in Hα emission. An inspection of the phase-space diagram for our sample suggests an anticorrelation between the HI and \rm H2 gas phases as galaxies fall into the cluster potential. This peculiar behaviour is a key signature of the ram-pressure stripping in action.