Interacting E+A System SDSS J161330.18+510335.5. I. Spatially Extended Poststarburst Signatures and Age Gradient

Abstract

An E+A galaxy and its neighbor were viewed with a long-slit spectrograph(FOCAS) mounted on the Subaru telescope. The galaxy is thought tobe experiencing a dynamical interaction with its neighbor, and wehave confirmed that the neighbor galaxy is at the same redshift.The neighbor galaxy shows no signs of current star formation or poststarburstactivity. We investigated the spatial extent of the poststarburstsignatures using long-slit spectroscopy of the E+A galaxy. The signaturesextend over more than 5 kpc from the core to the tidal plume, whichsuggests that the starburst was a galaxy-wide phenomenon. We founda positive gradient in the age of young stars from the center tothe outer regions of the plume.