to observe turbulent gas without an active AGN. AGN are seen to turn on and off with timescales of $\sim10^4 - 10^5$ years [@Lintott2009; @Keel2017], and the timescale for turbulent energy from AGN to deplete is $\sim 10^7 - 10^8$ years [@Guillard2015]. One possible example of this is seen by @Prieto2016, who observe light echoes from past AGN activity in a post-starburst galaxy with a LINER-like center. AGN activity is also observed to suppress star formation in CO-traced gas [@Ho2005; @Nesvadba2011; @Guillard2015; @Lanz2016]. Thus, while the details of how kinetic energy injected into the gas might lower the low dense gas fraction are still not understood, these post-starburst galaxies may have experienced recent AGN activity strong enough to disrupt the molecular gas and suppress star formation.

Evolution to Early Type Galaxies
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The presence of large CO-traced molecular gas reservoirs in half of the post-starbursts studied also presents a puzzle in understanding how these post-starburst galaxies can evolve to normal early type galaxies. Post-starburst galaxies have stellar populations, color gradients, morphologies, and kinematics consistent with reaching the red sequence of early type galaxies in [@Norton2001; @Yang2004; @Yang2008; @Pracy2013; @Pawlik2015] in a few Gyr. However, early type galaxies are typically gas-poor, 