Multi-line modelling in nearby galaxies: The link between dense gas and star formation in different environments

The J =1–0 lines of HCN and HCO + have become the default tracers dense molecular gas in external galaxies. To study relation between emission density, we mapped their =3–2 with ALMA Compact Array (ACA) nearby star-forming galaxies NGC3351, NGC3627, NGC4321. Combined archival line maps HCN(1–0), (1–0), CO(1–0), CO(2–1), use this data set to: (1) compare excitation normal starburst/AGN galaxies; (2) explore how ratios vary across galaxy disks; (3) infer density distribution other cloud properties on a pixel-by-pixel basis through physically-motivated radiative transfer model.