Astronomy departmental seminar - Kelley Hess (CSIC)


Ram pressure stripping in galaxy cluster substructure


In the cluster environment, a galaxy’s motion through the ICM results in a loss of the multi-phase interstellar medium through ram pressure stripping. This can be seen through the displacement of neutral and ionized gas, and triggered star formation. To date, the impact of ram pressure has been considered almost exclusively from the stand point of individual galaxies. However, a large fraction of cluster members have been accreted as members of groups, which contain their own warm/hot intragroup medium. We present a multi-wavelength study including exquisite MeerKAT HI and DECam Halpha imaging of the center of the Hydra Cluster and a foreground galaxy group. Members of the group exhibit compressed HI contours, well-defined HI tails, and ongoing star formation in the stripped gas. We use the HI and stellar morphologies, combined with a Beta model of the hot ICM, to constrain the galaxy orbits and real distances of the galaxies to the cluster center. It’s likely that the group has already passed its pericenter and is actually on “out fall” from the cluster. The high surviving HI content of the galaxies may suggest that the substructure/intragroup medium or CGM can protect them from the harshest effects of ram pressure, or that the galaxies are on more tangential orbits.