Shocking Tails in the Major Merger Abell 2744
  We identify four rare "jellyfish" galaxies in Hubble Space Telescope imagery
of the major merger cluster Abell 2744. These galaxies harbor trails of
star-forming knots and filaments which have formed in-situ in gas tails
stripped from the parent galaxies, indicating they are in the process of being
transformed by the environment. Further evidence for rapid transformation in
these galaxies comes from their optical spectra, which reveal starburst,
poststarburst and AGN features. Most intriguingly, three of the jellyfish
galaxies lie near ICM features associated with a merging "Bullet-like"
subcluster and its shock front detected in Chandra X-ray images. We suggest
that the high pressure merger environment may be responsible for the star
formation in the gaseous tails. This provides observational evidence for the
rapid transformation of galaxies during the violent core passage phase of a
major cluster merger.
