SIMBAD references

Aims. The complexity of star formation at the physical scale of molecular clouds is not yet fully understood. We investigate the mechanisms regulating the formation of stars in different environments within nearby star-forming galaxies from the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) sample.
Methods. Integral field spectroscopic data and radio-interferometric observations of 18 galaxies were combined to explore the existence of the resolved star formation main sequence (Σ_stellar versus Σ_SFR), resolved Kennicutt-Schmidt relation (Σ_mol. gas_ versus Σ_SFR), and resolved molecular gas main sequence (Σ_stellar versus Σ_mol. gas_), and we derived their slope and scatter at spatial resolutions from 100pc to 1kpc (under various assumptions).
Results. All three relations were recovered at the highest spatial resolution (100pc). Furthermore, significant variations in these scaling relations were observed across different galactic environments. The exclusion of non-detections has a systematic impact on the inferred slope as a function of the spatial scale. Finally, the scatter of the Σ_mol. gas + stellar_ versus Σ_SFR correlation is smaller than that of the resolved star formation main sequence, but higher than that found for the resolved Kennicutt-Schmidt relation.
Conclusions. The resolved molecular gas main sequence has the tightest relation at a spatial scale of 100pc (scatter of 0.34dex), followed by the resolved Kennicutt-Schmidt relation (0.41 dex) and then the resolved star formation main sequence (0.51 dex). This is consistent with expectations from the timescales involved in the evolutionary cycle of molecular clouds. Surprisingly, the resolved Kennicutt-Schmidt relation shows the least variation across galaxies and environments, suggesting a tight link between molecular gas and subsequent star formation. The scatter of the three relations decreases at lower spatial resolutions, with the resolved Kennicutt-Schmidt relation being the tightest (0.27 dex) at a spatial scale of 1 kpc. Variation in the slope of the resolved star formation main sequence among galaxies is partially due to different detection fractions of Σ_SFR with respect to Σ_stellar.