The impact of stellar bars on star-formation quenching: Insights from a spatially resolved analysis in the local Universe (2404.11656v2)

Abstract: Stellar bars are common morphological structures in the local Universe; according to optical and NIR surveys, they are present in about two-thirds of disc galaxies. These elongated structures are also believed to play a crucial role in secular evolutionary processes, because they are able to efficiently redistribute gas, stars, and angular momentum within their hosts, although it remains unclear as to whether they enhance or suppress star formation. A useful tool to investigate this ambiguity is the main sequence (MS) relation, which tightly links stellar mass ($M_{\star}$) and star formation rate (SFR). The main goal of this work is to explore star-formation processes in barred galaxies in order to assess the relevance of bars in star-formation quenching and whether or not they affect the typical log-linear trend of the resolved MS. To this purpose, we carried out a spatially resolved analysis on subkiloparsec (subkpc) scales for a sample of six nearby barred galaxies. We collected multi-wavelength photometric data from far-ultraviolet (FUV) to far-infrared (FIR) from the DustPedia database and applied a panchromatic spectral energy distribution (SED) fitting procedure on square apertures of fixed angular size (8" $\times$ 8") using the magphys code. For each galaxy, we obtain the distributions of stellar mass and SFR surface density and relate them in the $\log \Sigma_{\star}$ - $\log \Sigma_{\rm SFR}$ plane, deriving the spatially resolved MS relation. Although significant galaxy-to-galaxy variations are in place, we infer the presence of a common anti-correlation track in correspondence with the bar-hosting region, which shows systematically lower SFRs. This central quiescent signature can be interpreted as the result of a bar-driven depletion of gas reservoirs and a consequent halting of star formation. Our findings appear to support an inside-out quenching scenario.

• The paper demonstrates that stellar bars cause a bending in the spatially resolved main sequence, leading to lower star formation rates in bar regions.
• It utilizes subkiloparsec SED fitting across six local barred galaxies to reveal distinct trends in stellar mass and SFR compared to unbarred counterparts.
• The study supports an inside-out quenching model, highlighting that central regions experience significant star formation decline due to bar-driven gas funneling.

The Impact of Stellar Bars on Star-Formation Quenching in Local Universe Galaxies

The subject of stellar bar dynamics in disc galaxies presents a compelling area of paper, particularly regarding their influence on secular evolutionary processes and star-formation activity. Approximately two-thirds of disc galaxies host these elongated structures, which have been hypothesized to significantly affect the redistribution of gas, stars, and angular momentum, ultimately impacting star-formation rates (SFRs). The paper "The impact of stellar bars on star-formation quenching: Insights from a spatially resolved analysis in the local Universe," explores this detailed relationship by leveraging a spatially resolved analysis at subkiloparsec scales across a sample of six barred galaxies.

Methodological Framework

The authors conduct a spatially resolved analysis on galaxies sourced from the DustPedia database, utilizing photometric data spanning from far-ultraviolet (FUV) to far-infrared (FIR). By deploying the magphys code for spectral energy distribution (SED) fitting, the paper addresses subkiloparsec regions within each galaxy. This approach facilitates the derivation of detailed distributions of stellar mass and SFR surface densities, which are then plotted in the plane of log $\Sigma_{\star}$ versus log $\Sigma_{\rm SFR}$ to discern the spatially resolved main sequence (MS) relation.

A critical aspect of the paper is the examination of six nearby barred galaxies, selected based on specific criteria to ensure proximity and morphological clarity without confounding elements such as significant AGN activity. The authors pay particular attention to the variation in SFR and stellar mass density within the bar regions of each galaxy, providing a basis for evaluating the influence of stellar bars on star formation quenching.

Key Findings

1. Main Sequence Bending: The paper confirms that barred regions in galaxies display a characteristic bending in the resolved MS relation, indicating lower SFRs relative to stellar mass densities in these sectors. This observation bolsters the hypothesis that stellar bars lead to an inward funneling of gas which, following starburst events, contributes to a depletion of the gas reservoir, thereby initiating star-formation quenching.
2. Galaxy Comparison: Through linear regression analysis of the $\log \Sigma_{\star}$ -- $\log \Sigma_{\rm SFR}$ plane, it becomes apparent that the slope and intercept of the MS relation for barred galaxies differ notably from those of unbarred counterparts. Importantly, extensive scatter is indicative of significant variability among different galaxies, suggesting a nuanced role of bars that is contingent on the specific galactic environment and evolutionary state.
3. Quenching Signature: The paper's results suggest an inside-out quenching scenario, corroborating the observed reduction in central star formation within barred systems. This implies that the bar's influence is most strongly felt closer to the galactic core, supporting prior theoretical predictions on bar-induced quenching mechanisms.

Theoretical and Practical Implications

The findings offer critical insights into the mechanisms at play in the cessation of star formation within galaxies and the role of morphological structures like bars. From a theoretical perspective, these insights challenge models of galaxy evolution by adding complexity to the interpretation of SFR modulations and their link to structural galaxy components.

This paper advises a greater focus on high-resolution simulations and broader samples that include both barred and unbarred galaxies across varying cosmic ages to further elucidate the nuanced impacts of structural dynamics on star formation. Additionally, dissecting the interactions between bars, AGN, and other morphologies remains a fertile ground for future research, promising to illuminate the multifaceted forces shaping galaxy evolution.

In summary, this comprehensive analysis of the impact of stellar bars on star-formation quenching in local universe disc galaxies provides strong empirical evidence that bars are likely significant drivers of quenching, influencing the evolutionary pathways of these cosmic structures. The implications of these findings extend beyond theoretical models, offering a refined lens through which to interpret the cosmic history of galaxy development.