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Arxiv: The Structure of Massive Star-Forming Galaxies from JWST and ALMA: Dusty, High Redshift Disk Galaxies Published: 6/5/2024 9:00:04 PM Updated: 9/20/2024 1:26:09 PM

Paper abstract: We present an analysis of the JWST NIRCam and MIRI morphological propertiesof 80 massive (\log_{10}(M_\ast[M_{\odot}])=11.2\pm0.1) dusty star-forminggalaxies at z=2.7^{+1.2}_{-0.7}, identified as sub-millimetre galaxies(SMGs) by ALMA, that have been observed as part of the JWST PRIMER project. Tocompare the structure of these massive, active galaxies to more typical lessactively star-forming galaxies, we define two comparison samples. The first of850 field galaxies matched in specific star-formation rate and redshift and thesecond of 80 field galaxies matched in stellar mass. We identify 20\pm5% ofthe SMGs as candidate late-stage major mergers, a further 40\pm10% aspotential minor mergers and 40\pm10% which have comparatively undisturbeddisk-like morphologies, with no obvious massive neighbours. These rates arecomparable to those for the field samples and indicate that the majority of thesub-millimetre-detected galaxies are not late-stage major mergers, but haveinteraction rates similar to the less-active population at z~2-3. Weestablish that SMGs have comparable near-infrared sizes to the less activepopulations, but exhibit lower S\'ersic indices, consistent with bulge-lessdisks and have more structured morphologies at 2\mum relative to 4\mum. Wefind evidence for dust reddening as the origin of the morphological differencesbetween the populations, identifying a strong correlation between theF200W-F444W pixel colour and the 870\mum surface brightness. We concludethat SMGs and less active galaxies at the same epochs share a common disk-likestructure, but the weaker bulge components of the SMGs results in a lowerdynamical stability. Consequently, instabilities triggered either secularly orby minor external perturbations result in higher levels of activity (and dustcontent) in SMGs compared to typical star-forming galaxies. [Abridged]