dust extinction values, and even so, the CO luminosities are systematically higher than expected from the low SFRs. Indeed, @Smercina2018 find the SFRs are still much lower than expected given the high CO luminosities when extinction-insensitive IR-based SFR tracers are used.

The two post-starburst galaxies targeted here have HCN/CO luminosity ratios which are low compared to star-forming galaxies and many early types. A similar effect is seen in the HCO$^+$/CO luminosity ratios. Here, we compare the post-starburst galaxies to several different galaxy types: early type [@Crocker2012], star-forming, and starbursting [@Gao2004]. We perform a Monte-Carlo analysis, drawing pairs of galaxies at random from these comparison samples, to test how unusual it is to find two galaxies with these HCN/CO luminosity ratios. Drawing from the combined sample of early type, star-forming, and starbursting galaxies, the probability of finding two galaxies with HCN/CO as low as the post-starbursts is 5%. Thus, the post-starbursts have relatively low HCN/CO luminosity ratios, and it is unlikely our observed upper limits are due to random selection. We also compare to the comparison galaxy populations individually, to address several specific questions.

Next we compare to the three galaxy types separately. The starbursting sample represents likely recent progenitors of 