Revealing the complex nature of the strong gravitationally lensed system H-ATLAS J090311.6+003906 using ALMA

Dye, S.; Furlanetto, C.; Swinbank, A.M.; Vlahakis, C.; Nightingale, J.W.; Dunne, L.; Eales, S.A.; Smail, Ian; Oteo, I.; Hunter, T.; Negrello, M.; Dannerbauer, H.; Ivison, R.J.; Gavazzi, R.; Cooray, A.; van der Werf, P.

Abstract

We have modelled Atacama Large Millimetre/sub-millimetre Array (ALMA) long baseline imaging of the strong gravitational lens system H-ATLAS J090311.6+003906 (SDP.81). We have reconstructed the distribution of band 6 and 7 continuum emission in the z = 3.042 source and determined its kinematic properties by reconstructing CO(5–4) and CO(8–7) line emission in bands 4 and 6. The continuum imaging reveals a highly non-uniform distribution of dust with clumps on scales of ∼200 pc. In contrast, the CO line emission shows a relatively smooth, disc-like velocity field which is well fitted by a rotating disc model with an inclination angle of (40 ± 5)° and an asymptotic rotation velocity of 320 km s−1. The inferred dynamical mass within 1.5 kpc is (3.5 ± 0.5) × 1010 M⊙ which is comparable to the total molecular gas masses of (2.7 ± 0.5) × 1010 M⊙ and (3.5 ± 0.6) × 1010 M⊙ from the dust continuum emission and CO emission, respectively. Our new reconstruction of the lensed Hubble Space Telescope near-infrared emission shows two objects which appear to be interacting, with the rotating disc of gas and dust revealed by ALMA distinctly offset from the near-infrared emission. The clumpy nature of the dust and a low value of the Toomre parameter of Q ∼ 0.3 suggest that the disc is in a state of collapse. We estimate a star formation rate in the disc of 470 ± 80 M⊙ yr−1 with an efficiency ∼65 times greater than typical low-redshift galaxies. Our findings add to the growing body of evidence that the most infrared luminous, dust obscured galaxies in the high-redshift Universe represent a population of merger-induced starbursts.

Citation

Dye, S., Furlanetto, C., Swinbank, A., Vlahakis, C., Nightingale, J., Dunne, L., …van der Werf, P. (2015). Revealing the complex nature of the strong gravitationally lensed system H-ATLAS J090311.6+003906 using ALMA. Monthly Notices of the Royal Astronomical Society, 452(3), 2258-2268. https://doi.org/10.1093/mnras/stv1442

• Journal Article Type: Article
• Acceptance Date: Jun 26, 2015
• Publication Date: Sep 21, 2015
• Deposit Date: Feb 9, 2016
• Publicly Available Date: Feb 12, 2016
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 452
• Issue: 3
• Pages: 2258-2268
• DOI: https://doi.org/10.1093/mnras/stv1442
• Keywords: Gravitational lensing: strong, Galaxies: structure.
• Public URL: https://durham-repository.worktribe.com/output/1389355