Bar Formation in Disc Galaxies: Internal Kinematics and Environmental Influence in MaNGA Galaxies

TL;DR

This study investigates how internal kinematics and environment influence bar formation in disc galaxies, revealing that internal processes primarily drive bars, with external interactions playing a secondary role, supported by MaNGA survey data.

Contribution

It provides observational evidence linking internal gravitational instabilities to bar formation and shows environmental effects modulate bar prevalence in galaxies.

Findings

Barred galaxies have more concentrated stellar mass distributions.

Barred galaxies exhibit lower stellar angular momentum within inner regions.

Bar fraction peaks in isolated and strongly interacting galaxies.

Abstract

We explore how the physical properties of disc galaxies relate to the presence of bars using data from the SDSS-IV MaNGA survey. By combining internal kinematical properties and environmental diagnostics, we find that barred galaxies are more frequently associated with centrally concentrated stellar mass distributions (within 1 and 2 effective radii) and exhibit lower values of the stellar angular momentum $\lambda_{Re}$. At fixed total stellar mass, barred galaxies exhibit: (i) higher stellar mass, and (ii) lower angular momentum, both in their inner regions than their unbarred counterparts. We find a bimodal dependence of the bar fraction on tidal interactions produced by the nearest neighbour. Specifically, the bar fraction peaks in the most isolated galaxies, where bars form unequivocally through internal secular processes, decreases at intermediate interaction strengths, and rises again in the strong interaction regime, likely reflecting the role of dense environments in sustaining or triggering bars. Our results suggest that internal gravitational instabilities are the primary driver of bar formation. External tidal perturbations play a secondary role, capable of triggering or enhancing bar formation in galaxies that are already internally predisposed. Our findings provide robust observational validation of theoretical bar formation and evolution models in galaxies.