A dozen new galaxies caught in the act: Gas stripping and extended emission line regions in the Coma cluster

Abstract

We present images of extended H-alpha clouds associated with 14 member galaxies in the Coma cluster obtained from deep narrow band imaging observations with Suprime-Cam at the Subaru Telescope. The parent galaxies of the extended H-alpha clouds are distributed farther than 0.2 Mpc from the peak of X-ray emission of the cluster. Most of the galaxies have colors bluer than g-r approx 0.5 and they account for 57% of the blue (g-r<0.5) bright (r<17.8 mag) galaxies in the central region of the Coma cluster. They reside near the red- and blue-shifted edges of the Coma cluster's radial velocity distribution. These findings suggest that the most of the parent galaxies were recently captured by the Coma cluster potential and are now infalling toward the cluster center with their disk gas being stripped off and producing the observed H-alpha clouds.