Jellyfish galaxies – a trace of ram pressure stripping
* Abstract
We investigate the impact of ram pressure stripping on star-forming dwarf galaxies with a multi-phase interstellar medium (ISM). We conduct radiation-hydrodynamical simulations for the galaxies with normal and gas-rich disks in an idealized environment. To mimic ram pressure in galaxy clusters, we impose varying winds on the simulated galaxies. We find that mild ram pressure effectively strips neutral and molecular hydrogen in the outer disks while boosting overall star formation activities. On the other hand, strong winds quench disk star formation within a few hundred mega years with intense disk stripping. The stripped clouds are quickly heated and scattered when mild ram pressure is exerted on the normal dwarf galaxy. Strong winds form evident gaseous tails behind the galaxies, but molecular clumps and new stars are found in a distant tail only in the gas-rich disk case. We confirm the in-situ formation of dense molecular clouds in the tail of the gas-rich galaxy via radiative cooling and gravitational collapse. We also compute H-alpha and X-ray surface brightness of the gas-rich galaxy. The disk, tail, and pure intra-cluster medium (ICM) have characteristic H-alpha-to-X-ray flux ratios due to ISM-ICM mixing. The flux ratios are in good agreement with recent observations in the disk and tail, indicating the role of the mixing in the formation of the observed jellyfish galaxies. Our results suggest that jellyfish features can emerge when an abundant ISM is stripped from gas-rich galaxies by strong ram pressure.
