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This study analyzed 344 barred galaxies using infrared imaging to measure the stellar mass in galactic bars and other structural components. The researchers found that more massive galaxies with prominent bulges contain more massive bars with higher bar-to-total mass ratios, and these galaxies tend to have longer bars relative to their size compared to galaxies without bulges. The findings suggest that bars in different mass galaxies may evolve through distinct pathways, influenced by the timing of disk formation and subsequent secular processes.
Why it matters
Understanding how galactic bars grow and evolve helps astronomers trace the internal dynamics and long-term evolution of disk galaxies like our Milky Way. This research provides quantitative constraints on theoretical models of galaxy formation and evolution, particularly regarding how internal structures redistribute stellar mass over cosmic time.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: Bars are stellar structures commonly found in disk galaxies and important agents of secular evolution. Quantifying the stellar mass content of bars provides a physically motivated approach to assess how bar growth depends on galaxy mass and internal structure. We perform a GALFITM multi-band mid-infrared two-dimensional decomposition of 344 barred galaxies from the Spitzer Survey of Stellar Structure in Galaxies ($S^4G$) in the 3.6 and 4.5 $mu$m bands. We estimate the stellar mass associated with each structural component (i.e., disk, bulge, bar, and nuclear point source) and investigate how bar properties correlate with global galaxy characteristics. Our final models consist of 2-4 components per galaxy, with the simplest configuration (disk + bar) typically associated with low-mass systems. We find that more massive galaxies with prominent bulges host more massive bars and higher median bar-to-total stellar mass ratios. These bulges generally present S'{e}rsic indices below 2, consistent with a photometric signature of nuclear stellar disks. Additionally, when we consider the relative bar lengths at a fixed galaxy mass, we find a bimodal distribution where galaxies with bulges host relatively longer bars compared to their bulgeless counterparts. These findings could be the result of different evolutionary paths, possibly linked to different disk formation epochs, allowing bars more time to grow in size and mass. Our study indicates that bar evolution may follow distinct pathways across different galaxy mass regimes, and is likely influenced by secular processes and environmental effects.