LEDA 126817 (RB 199) — A ram pressure stripped, merging, blue E+A galaxy located inside a galactic filament in the Coma cluster

We present data and analysis of an E+A galaxy with ram pressure stripping and merger characteristics inside a galactic filament within the Coma cluster. E+A galaxies are post-starburst galaxies that have recently undergone complete quenching of their star formation and now lie in the “green valley” transition zone between blue and red galaxies, making them a valuable source for studying the evolution of galaxies. Bluer E+A galaxies tend to be younger, giving us a picture of how young galaxies transform into E+A galaxies. Using data from DR16 of the Sloan Digital Sky Survey, we analyzed a color selected sample of 1,520 galaxies near the Coma Cluster from the MaNGA (Mapping of Nearby Galaxies at APO) catalog. We identified 134 E+A galaxies using their optical spectra, based on their spectral shape, u-r color, lack of Hα emission, and hydrogen Balmer absorption. Of these 134 E+A galaxies, we classified 13 as “blue” based on their color magnitudes and spectral appearance. We found that 8 of these “blue” E+A galaxies were located inside a galactic filament emanating from the center of the Coma Cluster. One such galaxy, LEDA 126817 (RB 199), displayed prominent merger morphology and narrow blue filaments and knots, which morphologically resemble a complex of “fireballs”, extending 80 kpc south from the galaxy. Using Hubble Space Telescope ACS observations from the Coma Cluster Legacy Survey, pixel-accurate magnitude maps were created from the F814W (I) filter and the F475W (B) filter. These magnitude maps were then used to analyze the small-scale structures, gas distribution, and stellar population of LEDA 126817. Subaru Suprime-camera observations in H-alpha, B, and R bands revealed long H-alpha tail-like structures emanating from the blue fireball structures. In conjunction with the Hubble observations, these Subaru telescope observations provide strong evidence for both dust and gas being removed from Leda 126817 by the hot intracluster medium through ram pressure stripping. We believe that the ram pressure stripping removed most of the gas from the two merging galaxies, effectively quickly quenching all star formation and forming a blue E+A galaxy.