2025/10/20 by Ikeda, Ryota, Iono, Daisuke, Tadaki, Ken-ichi +19
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2510.18006
We present an analysis of rest-frame optical and far-infrared continuum emission in three luminous submillimeter galaxies (SMGs) at 3.0\lesssim z\lesssim4.5. The SMGs are spatially resolved down to 400-500 pc (∼0.05'') resolution by James Webb Space telescope (JWST) and Atacama Large Millimeter/submillimeter Array (ALMA) observations. Despite similarities in their observed far-infrared properties (flux density, infrared luminosity, and effective radius), the three SMGs exhibit heterogeneous morphologies both across wavelengths and among the sources themselves. While two of them (AzTEC-4 and AzTEC-8) show a disk-like structure in optical continuum, AzTEC-1 is dominated by highly concentrated component with the Sérsic index of n=5.4, where its far-infrared continuum emission is clumpy and less concentrated. AzTEC-4, which is confirmed to be at z=4.198, shows a two-arm spiral of dust, but not in the stellar distribution. These three SMGs exemplify that multiple physical mechanisms exist in triggering starbursts in luminous SMGs at high redshift: secular instability in gas disks (AzTEC-4) in addition to possible minor mergers (AzTEC-8), and a combination of the efficient gas supply to the central core induced by a gas-rich major merger and the reformation of cold gas disk (AzTEC-1).