Evidence for mixing between ICM and stripped ISM by the analysis of the gas metallicity in the tails of jellyfish galaxies

Andrea Franchetto, Stephanie Tonnesen, Bianca M. Poggianti, Benedetta Vulcani, Marco Gullieuszik, Alessia Moretti, Rory Smith, Alessandro Ignesti, Cecilia Bacchini, Sean McGee, Neven Tomičić, Matilde Mingozzi, Anna Wolter, Ancla Müller

Published 2021-11-08Version 1

Hydrodynamical simulations show that the ram-pressure stripping in galaxy clusters fosters a strong interaction between stripped interstellar medium (ISM) and the surrounding medium, with the possibility of intracluster medium (ICM) cooling into cold gas clouds. Exploiting the MUSE observation of three jellyfish galaxies from the GAs Stripping Phenomena in galaxies with MUSE (GASP) survey, we explore the gas metallicity of star-forming clumps in their gas tails. We find that the oxygen abundance of the stripped gas decreases as a function of the distance from the parent galaxy disk; the observed metallicity profiles indicate that more than 40% of the most metal-poor stripped clouds are constituted by cooled ICM, in qualitative agreement with simulations that predict mixing between the metal-rich ISM and the metal-poor ICM.