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Arxiv: A multi-wavelength investigation of spiral structures in z > 1 galaxies with JWST Published: 1/6/2025 9:00:10 PM Updated: 1/6/2025 9:00:10 PM

Paper abstract: Recent JWST observations have revealed the prevalence of spiral structures atz > 1. Unlike in the local Universe, the origin and the consequence ofspirals at this epoch remain unexplored. We use public JWST/NIRCam data fromthe COSMOS-Web survey to map spiral structures in eight massive (>10^{10.5}\,\rm M_{\odot}) star-forming galaxies at z_{\rm spec} ~ 1.5. Wepresent a method for systematically quantifying spiral arms at z>1, enablingdirect measurements of flux distributions. Using rest-frame near-IR images, weconstruct morphological models accurately tracing spiral arms. We detectoffsets (~ 0.2 - 0.8\,\rm kpc) between the rest-frame optical and near-IRflux distributions across most arms. Drawing parallels to the local Universe,we conclude that these offsets reflect the presence of density waves. For nineout of eighteen arms, the offsets indicate spiral shocks triggered by densitywaves. Five arms have offsets in the opposite direction and are likelyassociated with tidal interactions. For the remaining cases with no detectedoffsets, we suggest that stochastic 'clumpy' star formation is the primarydriver of their formation. In conclusion, we find a multi-faceted nature ofspiral arms at z > 1, similar to that in the local Universe.