Mid-Infrared Emission as a Tracer of Gas and Star Formation in M51

Recent research efforts highlight that the mid-infrared (mid-IR) dust emission shows a strong relationship with both molecular gas and star formation in galaxies across various spatial scales, establishing it as a powerful probe of the interstellar medium. Building on these findings, I will present an investigation of the correlations of mid-IR emission with gas and star formation in M51, leveraging the high-resolution JWST wide-band imaging covering all MIRI filters (at 5.6, 7.7, 10, 11.3, 12.8, 15, 18, and 21 um) complemented by a rich ancillary dataset. We find that the mid-IR and molecular gas traced by 12CO(1-0) intensities exhibit near-linear slopes and a strong correlation that remains consistent across all mid-IR bands at ~50 pc scale. We observe a similar trend between mid-IR and H-alpha emission tracing star formation, with correlations strengthening in nebular regions. I will also discuss how the correlations of mid-IR emission with atomic gas (HI) and total gas (H I + H2) change, finding a strong correlation coefficient of $\sim$0.9 across all bands for the latter. Our results reveal the dependence of dust emission on both the gas column density and stochastic heating from UV photons. These findings will aid future studies in using mid-IR emission as a tracer of gas and star formation.