A Dozen New Galaxies Caught In The Act: Gas Stripping And Extended Emission Line Regions In The Coma Cluster

We present images of extended H alpha clouds associated with 14 member galaxies in the Coma cluster obtained from deep narrowband imaging observations with the 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 the X-ray emission of the cluster. Most of the galaxies are bluer than g - r approximate to 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 blueshifted edges of the radial velocity distribution of Coma cluster member galaxies. Our findings suggest that 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.