2012ApJ...752..111N

We have obtained high-resolution data of the z ∼ 2 ring-like, clumpy star-forming galaxy (SFG) ZC406690 using the VLT/SINFONI with adaptive optics (in K band) and in seeing-limited mode (in H and J bands). Our data include all of the main strong optical emission lines: [O II], [O III], Hα, Hβ, [N II], and [S II]. We find broad, blueshifted Hα and [O III] emission line wings in the spectra of the galaxy's massive, star-forming clumps (σ ∼ 85 km/s) and even broader wings (up to 70% of the total Hα flux, with σ ∼ 290 km/s) in regions spatially offset from the clumps by ∼2 kpc. The broad emission likely originates from large-scale outflows with mass outflow rates from individual clumps that are 1-8x the star formation rate (SFR) of the clumps. Based on emission line ratio diagnostics ([N II]/Hα and [S II]/Hα) and photoionization and shock models, we find that the emission from the clumps is due to a combination of photoionization from the star-forming regions and shocks generated in the outflowing component, with 5%-30% of the emission deriving from shocks. In terms of the ionization parameter (6x10⁷ to 10⁸ cm/s, based on both the SFR and the O₃₂ ratio), density (local electron densities of 300-1800/cm3 in and around the clumps, and ionized gas column densities of 1200-8000 M_☉/pc2^), and SFR (10-40 M_☉/yr), these clumps more closely resemble nuclear starburst regions of local ultraluminous infrared galaxies and dwarf irregulars than H II regions in local galaxies. However, the star-forming clumps are not located in the nucleus as in local starburst galaxies but instead are situated in a ring several kpc from the center of their high-redshift host galaxy, and have an overall disk-like morphology. The two brightest clumps are quite different in terms of their internal properties, energetics, and relative ages, and thus we are given a glimpse at two different stages in the formation and evolution of rapidly star-forming giant clumps at high-z.