Determinants of bar-driven shear strength and the shear threshold for star formation inhibition

Identify the specific barred-galaxy properties that govern the magnitude of bar-driven shear along bar dust lanes and ascertain the threshold shear strength at which star formation is inhibited in these regions.

Background

Throughout the paper, the authors quantify velocity gradients (a proxy for shear and shocks) along bar dust lanes in four nearby barred galaxies using PHANGS-MUSE and PHANGS-ALMA data. They find pronounced velocity jumps and establish that star formation is hindered where velocity gradients are high. Their findings align with numerical simulations suggesting shear inhibits star formation in bars.

Despite these results, the authors point out that the underlying determinants of shear strength in barred galaxies and the quantitative threshold at which shear suppresses star formation remain undetermined, motivating future theoretical and numerical work to clarify these controls.