Infoscience

Journal article

[C II] AND (CO)-C-12(1-0) EMISSION MAPS IN HLSJ091828.6+514223: A STRONGLY LENSED INTERACTING SYSTEM AT z=5.24

We present Submillimeter Array [ C II] 158 mu m and Karl G. Jansky Very Large Array (CO)-C-12(1-0) line emission maps for the bright, lensed, submillimeter source at z = 5.2430 behind A 773: HLSJ091828.6+514223 (HLS0918). We combine these measurements with previously reported line profiles, including multiple 12CO rotational transitions, [C II], water, and [N II], providing some of the best constraints on the properties of the interstellarmedium in a galaxy at z > 5. HLS0918 has a total far-infrared (FIR) luminosity L-FIR(8-1000 mu m) = (1.6 +/- 0.1) x 1014 L-circle dot mu(-1), where the total magnification mu(total) = 8.9 +/- 1.9, via a new lens model from the [C II] and continuum maps. Despite a HyLIRG luminosity, the FIR continuum shape resembles that of a local LIRG. We simultaneously fit all of the observed spectral line profiles, finding four components that correspond cleanly to discrete spatial structures identified in the maps. The two most redshifted spectral components occupy the nucleus of a massive galaxy, with a source-plane separation < 1 kpc. The reddest dominates the continuum map (demagnified L-FIR,L- (component) = (1.1 +/- 0.2) x10(13) L-circle dot) and excites strong water emission in both nuclear components via a powerful FIR radiation field from the intense star formation. A third star-forming component is most likely a region of a merging companion (Delta V similar to 500 kms(-1)) exhibiting generally similar gas properties. The bluest component originates from a spatially distinct region and photodissociation region analysis suggests that it is lower density, cooler, and forming stars less vigorously than the other components. Strikingly, it has very strong [N II] emission, which may suggest an ionized, molecular outflow. This comprehensive view of gas properties and morphology in HLS0918 previews the science possible for a large sample of high-redshift galaxies once ALMA attains full sensitivity.

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