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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.

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


Authors

S. Dye

C. Furlanetto

C. Vlahakis

J.W. Nightingale

L. Dunne

S.A. Eales

I. Oteo

T. Hunter

M. Negrello

H. Dannerbauer

R.J. Ivison

R. Gavazzi

A. Cooray

P. van der Werf



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.

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

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






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