Speaker
Description
Stellar bars play an important role in regulating the evolution and morphology of disk galaxies and are very common, appearing in about 70% of local massive disk galaxies. Through their rotation, they redistribute stars and gas toward the central regions, feeding central black holes and contributing to the bulge growth. Over time, the angular momentum transferred from the bar to its host galaxy alters the galaxy's structure, and, at the same time, causes the bar to grow, strengthen, and slow down. Two main pathways have been proposed for bar formation. First, formation in isolation through internal secular processes. In this scenario, disk instabilities trigger stellar migration towards the central region of the galaxy naturally forming a bar. This mechanism has been widely studied and is relatively well understood. However, bar formation in isolation alone cannot reproduce all observed properties of barred galaxies. Second, bar formation triggered by galaxy interactions. A wide range of merger configurations can lead to bar formation. Bars may appear after major mergers, where galaxies of comparable mass merge into a single structure, after fly-bys or weak interactions, or before minor mergers with similarly oriented galaxies. Up to now, this scenario has been mostly investigated through Hydrodynamical simulations. The same studies suggest that a way to distinguish between bars formed in isolation and those triggered by interactions is to examine the spatial distribution of ionised gas and star formation. Galaxies evolving in isolation are expected to show relatively homogeneous, undisturbed star formation across their disk and bar regions. In contrast, merger-induced bars may display enhanced activity in the central regions and at the bar ends. They may show lower star formation along the bar length and a generally more asymmetric, disturbed distribution over the disk.
The INTERBARS program (PI V. Cuomo) observed a sample of 34 interacting barred galaxies using broadband g, r, and narrowband Hα filters with OmegaCAM at the VST. The sample was initially selected from Galaxy Zoo 2 by identifying barred galaxies. A second selection step isolated systems with at least one merger classification, indicating an interaction. From this parent sample, a redshift cut (z < 0.03) was applied. The candidates were then visually inspected to confirm the presence of the bar and to characterise the interaction type (pre-merger, post-merger, fly-by, or merger). Finally, were selected the galaxies observable during semester 2023B and with available deep LegacySurvey (LS) imaging. The VST Hα maps will allow us to characterize the resolved star formation distribution of the targets isolating the disk, bar and central regions. The structural parameters will be derived from the LS imaging and related to the star-formation. Lastly, we will investigate the larger environments around the sample galaxies thanks to the large VST FOV.
Of the 34 targets, 27 were observed, and 3 were only partially covered. I will present ongoing work on data reduction and continuum subtraction, along with preliminary results on the Hα distribution for a subsample of reduced observations.