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, Loretta ORCID: https://orcid.org/0000-0001-9880-2543, Eales, Stephen Anthony ORCID: https://orcid.org/0000-0002-7394-426X, Smail, Ian, Oteo, I., Hunter, T., Negrello, Mattia ORCID: https://orcid.org/0000-0002-7925-7663, Dannerbauer, H., Ivison, R. J., Gavazzi, R., Cooray, A. and Werf, P. van der 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) , pp. 2258-2268. 10.1093/mnras/stv1442

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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.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Uncontrolled Keywords:	gravitational lensing: strong; galaxies: structure
Publisher:	Oxford University Press
ISSN:	0035-8711
Date of First Compliant Deposit:	11 September 2017
Date of Acceptance:	26 June 2015
Last Modified:	16 Oct 2023 06:22
URI:	https://orca.cardiff.ac.uk/id/eprint/77737

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