Strong Bars, Strong Inflow : The Effect of Bar Strength on Gas Inflow

Magnan, Maëlle and Géron, Tobias and Garland, Izzy L. and Lintott, Chris J. and Makechemu, Jason Shingirai and O’Ryan, David and Simmons, Brooke D. and Smethurst, Rebecca J. (2025) Strong Bars, Strong Inflow : The Effect of Bar Strength on Gas Inflow. Research Notes of the AAS, 9 (12): 341. ISSN 2515-5172

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Abstract

Stellar bars are elongated structures in disk galaxies that can torque and funnel gas inward, influencing galaxy evolution. While strong bars are known to induce rapid inflow, the impact of weaker bars remains less certain. We collected spectroscopic data using the Isaac Newton Telescope to analyze 18 nearby galaxies (strongly barred, weakly barred, and unbarred) drawn from Galaxy Zoo DESI. We obtained spatial profiles of equivalent width (EW) and ionized gas velocity dispersion by fitting Gaussian profiles to the Hα emission line. Strongly barred galaxies exhibit a distinctive three-peaked EW[Hα] structure, consistent with inward funneling of gas. Weakly barred systems lack this pattern, which suggests limited inflow. Velocity dispersion distributions further distinguish the bar types, with strongly barred galaxies showing significantly higher values than weakly barred and unbarred systems. These results suggest that strong bars drive gas inflow, while weak bars exert a limited dynamical influence.