Bitten Gullberg — Page 2

arXiv2015

The Mysterious Morphology of MRC0943-242 as Revealed by ALMA and MUSE

We present a pilot study of the z=2.923 radio galaxy MRC0943-242, where we for the first time combine information from ALMA and MUSE data cubes. Even with modest integration times, we disentangle an AGN and a starburst dominated set of components. These data reveal a highly complex morphology, as the AGN, starburst, and molecular gas components show up as widely separated sources in dust continuum, optical continuum and CO line emission observations. CO(1-0) and CO(8-7) line emission suggest that there is a molecular gas reservoir offset from both the dust and the optical continuum that is located ~90kpc from the AGN. The UV line emission has a complex structure in emission and absorption. The line emission is mostly due to i) a large scale ionisation cone energised by the AGN, ii) a Ly-alpha emitting bridge of gas between the radio galaxy and a heavily star-forming set of components. Strangely, the ionisation cone has no Ly-alpha emission. We find this is due to an optically thick layer of neutral gas with unity covering fraction spread out over a region of at least ~100kpc from the AGN. Other, less thick absorption components are associated with Ly-alpha emitting gas within a few tens of kpc from the radio galaxy and are connected by a bridge of emission. We speculate that this linear structure of dust, Ly-alpha and CO emission, and the redshifted absorption seen in the circum-nuclear region may represent an accretion flow feeding gas into this massive AGN host galaxy.

astro-ph.GA↗

arXiv2015

The nature of the [CII] emission in dusty star-forming galaxies from the SPT survey

We present [CII] observations of 20 strongly lensed dusty star forming galaxies at 2.1 < z < 5.7 using APEX and Herschel. The sources were selected on their 1.4 mm flux (S_1.4mm > 20 mJy) from the South Pole Telescope survey, with far-infrared (FIR) luminosities determined from extensive photometric data. The [CII] line is robustly detected in 17 sources, all but one being spectrally resolved. Eleven out of 20 sources observed in [CII] also have low-J CO detections from ATCA. A comparison with mid- and high-J CO lines from ALMA reveals consistent [CII] and CO velocity profiles, suggesting that there is little differential lensing between these species. The [CII], low-J CO and FIR data allow us to constrain the properties of the interstellar medium. We find [CII] to CO(1-0) luminosity ratios in the SPT sample of 5200 +- 1800, with significantly less scatter than in other samples. This line ratio can be best described by a medium of [CII] and CO emitting gas with a higher [CII] than CO excitation temperature, high CO optical depth tau_CO >> 1, and low to moderate [CII] optical depth tau_CII ~< 1. The geometric structure of photodissociation regions allows for such conditions.

astro-ph.GA↗