J0107a: A Barred Spiral Dusty Star-forming Galaxy at $z=2.467$

Dusty Star-Forming Galaxies (DSFGs) are amongst the most massive and active star-forming galaxies during the cosmic noon. Theoretical studies have proposed various formation mechanisms of DSFGs, including major merger-driven starbursts and secular star-forming disks. Here, we report J0107a, a bright ($\sim 8$ mJy at observed-frame 888 $\mu$m) DSFG at $z=2.467$ that appears to be a gas-rich massive disk and might be an extreme case of the secular disk scenario. J0107a has a stellar mass $M_{\star }\sim 5\times {10}^{11}{M}_{\odot }$, molecular gas mass $M_{\mathrm{m}\mathrm{o}\mathrm{l}}\sim (1\text{textendash}6)\times {10}^{11}{M}_{\odot }$, and a star formation rate (SFR) of $\sim 500M_{\odot }$ yr${}^{-1}$. J0107a does not have a gas-rich companion. The rest-frame 1.28 $\mu$m JWST NIRCam image of J0107a shows a grand-design spiral with a prominent stellar bar extending $\sim 15$ kpc. ALMA band 7 continuum map reveals that the dust emission originates from both the central starburst and the stellar bar. 3D disk modeling of the CO(4-3) emission line indicates a dynamically cold disk with rotation-to-dispersion ratio $V_{\mathrm{m}\mathrm{a}\mathrm{x}}\mathrm{/}\sigma \sim 8$. The results suggest a bright DSFG may have a non-merger origin, and its vigorous star formation may be triggered by bar and/or rapid gas inflow.