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 ($\sim2.25$ kpc/arcsec) with Keck/NIRC2. We identify 15 stellar clumps in G04-1 with a range of masses from $3.6 \times 10^{6}$ to $2.7 \times 10^{8}\ \rm M_{\odot}$, and with a median mass of $\sim2.9 \times 10^{7}\ \rm M_{\odot}$. 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 H$\alpha$ maps ($\sim2.75$ kpc/arcsec; $<$R$_{clump}> \sim$500 pc) and appear co-located ($\overline{\Delta x} \sim 0.1$ arcsec). 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 observation of a number of clumps with masses $10^{7}-10^{8}\ \rm M_{\odot}$ is not consistent with strong radiative feedback in this galaxy.