2025/10/27 by La Marca, A., Nardone, M. T., Wang, L. +3
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2510.23522
We investigate the role of galactic bars in fuelling and triggering Active Galactic Nucleus (AGN) in disc galaxies up to z∼ 0.8. We utilise a Deep Learning model, fine-tuned on Galaxy Zoo volunteer classifications, to identify (strongly and weakly) barred and unbarred disc galaxies in Hyper Suprime-Cam Subaru Strategic Program i-band images. We select AGN using three independent diagnostics: mid-infrared colours, X-ray detections, and spectral energy distribution (SED) fitting. The SED analysis, performed using CIGALE, quantifies the relative AGN contribution to the total galaxy luminosity (f\rm AGN) and the AGN luminosity (L\rm disc). We assess the impact of bars by comparing AGN incidence and properties in barred galaxies against carefully constructed redshift-, stellar mass-, and colour-matched unbarred control samples. Our binary AGN classification experiment demonstrates that barred disc galaxies host a statistically detectable higher fraction of AGN compared to their unbarred counterparts, suggesting a contributing role for bars in the global AGN budget. The contribution of bars to AGN fuelling appears confined to systems where the AGN has a lower relative contribution to the host galaxy's emission (f\rm AGN < 0.75). Crucially, we find a significant dearth of barred disc galaxies hosting AGN with f\rm AGN > 0.75, independent of bar strength. Consistent with this, the fraction of barred galaxies among AGN hosts decreases with increasing L\rm disc. Combined with previous results, we suggest that bars contribute to fuelling the population of low-to-moderate luminosity AGN, but major mergers are the principal mechanism for triggering the most powerful and dominant accretion events.