K-band Imaging of the Nearby Clumpy, Turbulent Disk Galaxy DYNAMO G04-1

Abstract

Abstract We present a case study of the stellar clumps in G04-1—a clumpy, turbulent disk galaxy located at z = 0.13—from the DYnamics of Newly-Assembled Massive Objects sample, using adaptive optics-enabled K-band imaging (∼2.25 kpc arcsec−1) with Keck-NIRC2. We identify 15 stellar clumps in G04-1 with a range of masses from 3.6 × 106–2.7 × 108 M ⊙, and a median mass of ∼ 2.9 × 107 M ⊙. Note that these masses decrease by about half when we apply a light correction for the underlying stellar disk. A majority (12 of 15) of the clumps observed in the K P -band imaging have associated components in Hα maps (∼2.75 kpc arcsec−1; <Rclump > ∼ 500 pc) and appear colocated ( Δ x ¯ ∼ 0 .″ 1 ). Using Hubble Space Telescope observations from the Wide Field Camera on the Advanced Camera for Surveys, with the F336W and F467M filters, we also find evidence of radial trends in the stellar properties of the clumps: the clumps closer to the center of G04-1 are more massive (consistent with observations in high-z systems) and appear more red, suggesting they may be more evolved. Using our high-resolution data, we construct a star-forming main sequence for G04-1 in terms of spatially resolved quantities, and find that all regions (both clump and intraclump) within the galaxy are experiencing an enhanced mode of star formation routinely observed in galaxies at high-z. In comparison to recent simulations, our observations of a number of clumps with masses of 107–108 M ⊙ are not consistent with strong radiative feedback in this galaxy.