Quantifying the Relationship of Dense Gas and Star Formation with DEGAS

We present the first results from the Dense Extragalactic GBT+Argus Survey (DEGAS), a Green Bank Telescope project that, when completed, will map 36 galaxies nearby spiral galaxies in four dense molecular gas tracers (HCN, HCO⁺, ¹³CO, C¹⁸O). We briefly describe DEGAS observing and preliminary data reduction strategies. We examine how the star formation efficiency of dense gas ratio (SFR/HCN) and the dense gas fraction (HCN/CO) depend on galaxy environment. We find that our preliminary data follows the linear relation between SFR and HCN and the positive correlation between the star formation efficiency of molecular gas and the dense gas fraction suggested in Gao and Solomon. We also find a negative correlation between the star formation efficiency of dense gas and the dense gas fraction. These results, suggest that a density threshold model for star formation is not the most effective way of explaining the relationship between dense gas and star formation