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

TL;DR

This paper reports the discovery of J0107a, a massive, gas-rich spiral galaxy at z=2.467 with active star formation, likely formed through secular processes rather than mergers, challenging traditional views on galaxy formation.

Contribution

It presents detailed multi-wavelength observations of J0107a, demonstrating a non-merger, secular disk galaxy with intense star formation at high redshift, supported by structural and kinematic analysis.

Findings

J0107a is a massive, gas-rich spiral galaxy at z=2.467.

The galaxy shows a grand-design spiral with a stellar bar.

It has a high star formation rate of about 500 solar masses per year.

Abstract

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 ($\sim8$ 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 $M_\star\sim5\times10^{11}M_\odot$, molecular gas mass $M_\mathrm{mol}\sim(1\textendash6)\times10^{11}M_\odot$, and a star formation rate (SFR) of $\sim500M_\odot$ 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 $\sim15$ 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 $V_\mathrm{max}/\sigma\sim8$. 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.