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

Abstract

We present a case study of stellar clumps in G04-1, a clumpy, turbulent disk galaxy located at z = 0.13 from the DYNAMO sample, using adaptive optics enabled K-band imaging (∼ 2.25 kpc/arcsec) with Keck/NIRC2. We identify 15 stellar clumps in G04-1 with a range of masses from 3.6 × 10 6 to 2.7 × 10 8 M , and with a median mass of ∼ 2.9 × 10 7 M . Note that these masses decrease by about one-half when we apply a light correction for the underlying stellar disk. A majority (12 of 15) of clumps observed in the K P -band imaging have associated components in Hα maps (∼ 2.75 kpc/arcsec; <R clump > ∼500 pc) and appear co-located (∆x ∼ 0.1 ). Using Hubble Space Telescope WFC/ACS observations with the F336W and F467M filters, we also find evidence of radial trends in clump stellar properties: clumps closer to the centre of G04-1 are more massive (consistent with observations at high-z) 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 intra-clump) 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 10 7 − 10 8 M is not consistent with strong radiative feedback in this galaxy.

Stellar Masses of Clumps in Gas-rich, Turbulent Disk Galaxies

“…They are typically more consistent with values found in 𝑧 ≈ 1.5 galaxies, rather than local spirals. White et al (2021) show that this remains true for the resolved relationship of Σ 𝑆𝐹 𝑅 − Σ 𝑠𝑡 𝑎𝑟 for one DYNAMO galaxy observed with Keck adaptive optics. They find Σ 𝑆𝐹 𝑅 that are a factor of ∼ 2× larger than the averages for 𝑧 ≈ 1 galaxies from the CANDELS survey (Wuyts et al 2013).…”