Offset of the barred Tully–Fisher relation relative to unbarred galaxies

Ascertain whether the stellar Tully–Fisher relation for barred galaxies is offset relative to that of unbarred galaxies in observational samples by analyzing larger and more recent datasets.

Background

In the Auriga simulations, barred galaxies are found to be more baryon-dominated than unbarred systems, leading to a predicted offset in the stellar Tully–Fisher relation (STFR), with barred galaxies lying above the unbarred relation at fixed rotation velocity. Observational studies have reported mixed results: some find an offset consistent with maximal discs in barred galaxies, while others find no significant difference, potentially due to sample size and measurement limitations.

Confirming or refuting an observational offset in the STFR between barred and unbarred galaxies has important implications for galaxy dynamics and for distinguishing between dark matter and modified gravity scenarios, as such an offset would naturally arise in dark matter frameworks but not in MOND-like theories with negligible intrinsic scatter.