A New Method for Measuring Star Formation Rate in NGC 1068 and Its Relation with Galactic Struct

Molecular clouds where star formation occurs are affected by galactic structures. Understanding the spatial distribution of star-forming regions is crucial to understanding the interplay between clouds and the host galaxy. However, the conventional SFR derivation methods contain uncertainties that lead to significant over/underestimation. Here, we present a new SFR calibration method based on ionized gas tracers, with essential corrections for extinction, diffuse ionized gas (DIG), and thermal dust contamination. The key aspect of our new SFR measurement is that we can estimate the electron temperature, which significantly affects the derived SFR based on ionized gas tracers. We used a pair of 60-pc-resolution datasets of ionized gas tracers, Paα observed by HST, and free-free continuum observed by ALMA. We derived 60-pc-scale SFR of the nearby typical spiral galaxy NGC 1068 to be 3.2 ± 0.5 Msun/yr (DIG-corrected) and 9.1 ± 1.4 Msun/yr (uncorrected), revealing the effect of DIG leading to an overestimation of SFR. Additionally, the high-resolution SFR map provides new perspectives (CO isotope abundance ratio vs SFR) on the star formation process by comparing the molecular gas mass distribution derived at the cloud scale. Our method provides a framework for future SFR studies, which can further be applied to a wider range of galaxies to investigate the relationship between star formation and galactic structure.