SDSS-IV MaNGA: Bar pattern speed estimates with the Tremaine-Weinberg method and their error sources

TL;DR

This study assesses uncertainties in measuring galaxy bar pattern speeds using the Tremaine-Weinberg method, analyzing error sources and their impact on results across a sample of galaxies.

Contribution

It characterizes key error sources affecting the Tremaine-Weinberg method and explores their influence on bar pattern speed estimates in a galaxy sample.

Findings

Uncertainties in galaxy center, PA, slit length, and resolution impact pattern speed estimates.

Most bars in the sample are slow or ultrafast, with no clear trend with galaxy type.

Potential correlations suggest massive galaxies host longer, slower bars and gas-rich discs have slower bar rotation.

Abstract

Estimating the bar pattern speed (\Om{}) is one of the main challenges faced in understanding the role of stellar bars in galaxy dynamical evolution. This work aims to characterise different uncertainty sources affecting the Tremaine Weinberg (TW)-method to study the correlation between bar and galaxies physical parameters. We use a sample of 15 MaNGA SDSS-IV galaxies and 3 CALIFA galaxies from \cite{Aguerri2015}. We studied the errors related with (i) galaxy centre determination, (ii) disc position angle (PA) emphasising the difficulties triggered by outer non-axisymmetric structures besides the bar, (iii) the slits length and (iv) the spatial resolution. In average, the PA uncertainties range $\sim 15 \%$, the slit length $\sim 9 \%$ and the centring error $\sim 5 \%$. Reducing the spatial resolution increases the sensitivity to the PA error. Through Monte Carlo simulations, we estimate the probability distribution of the \R{} bar speed parameter. The present sample is composed of 7 slow, 4 fast and 7 ultrafast bars, with no trend with morphological types. Although uncertainties and low sample numbers may mask potential correlations between physical properties, we present a discussion of them: We observe an anti-correlation of \Om{} with the bar length and the stellar mass, suggesting that massive galaxies tend to host longer and slower bars. We also observe a correlation of the molecular gas fraction with \R{}, and a weak anti-correlation with \Om{}, suggesting that bars rotate slower in gaseous discs. Confirmation of such trends awaits future studies.