Evidence of ongoing AGN-driven feedback in a quiescent post starburst
  E+A galaxy
  Post starburst E+A galaxies are thought to have experienced a significant
starburst that was quenched abruptly. Their disturbed, bulge-dominated
morphologies suggest that they are merger remnants. We present ESI/Keck
observations of SDSS J132401.63+454620.6, a post starburst galaxy at redshift z
= 0.125, with a starburst that started 400 Myr ago, and other properties, like
star formation rate (SFR) consistent with what is measured in ultra luminous
infrared galaxies (ULRIGs). The galaxy shows both zero velocity narrow lines,
and blueshifted broader Balmer and forbidden emission lines (FWHM=1350 +- 240
km/s). The narrow component is consistent with LINER-like emission, and the
broader component with Seyfert-like emission, both photoionized by an active
galactic nucleus (AGN) whose properties we measure and model. The velocity
dispersion of the broad component exceeds the escape velocity, and we estimate
the mass outflow rate to be in the range 4-120 Mo/yr. This is the first
reported case of AGN-driven outflows, traced by ionized gas, in post starburst
E+A galaxies. We show, by ways of a simple model, that the observed AGN-driven
winds can consistently evolve a ULIRG into the observed galaxy. Our findings
reinforce the evolutionary scenario where the more massive ULIRGs are quenched
by negative AGN feedback, evolve first to post starburst galaxies, and later
become typical red and dead ellipticals.
