The Herschel-ATLAS: magnifications and physical sizes of 500-μm-selected strongly lensed galaxies

Enia, A. and Negrello, M. and Gurwell, M. and Dye, S. and Rodighiero, G. and Massardi, M. and de Zotti, G. and Franceschini, A. and Cooray, A. and van der Werf, Paul and Birkinshaw, M. and Michałowski, M.J. and Oteo, I. (2018) The Herschel-ATLAS: magnifications and physical sizes of 500-μm-selected strongly lensed galaxies. Monthly Notices of the Royal Astronomical Society, 475 (3). pp. 3467-3484. ISSN 0035-8711

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We perform lens modelling and source reconstruction of Sub-millimetre Array (SMA) data for a sample of 12 strongly lensed galaxies selected at 500μm in the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). A previous analysis of the same data set used a single Sérsic profile to model the light distribution of each background galaxy. Here we model the source brightness distribution with an adaptive pixel scale scheme, extended to work in the Fourier visibility space of interferometry. We also present new SMA observations for seven other candidate lensed galaxies from the H-ATLAS sample. Our derived lens model parameters are in general consistent with previous findings. However, our estimated magnification factors, ranging from 3 to 10, are lower. The discrepancies are observed in particular where the reconstructed source hints at the presence of multiple knots of emission. We define an effective radius of the reconstructed sources based on the area in the source plane where emission is detected above 5σ. We also fit the reconstructed source surface brightness with an elliptical Gaussian model. We derive a median value reff ∼ 1.77 kpc and a median Gaussian full width at half-maximum ∼1.47 kpc. After correction for magnification, our sources have intrinsic star formation rates (SFR) ∼ 900–3500 M⊙ yr−1, resulting in a median SFR surface density ΣSFR ∼ 132 M⊙ yr−1 kpc−2 (or ∼218 M⊙ yr−1 kpc−2 for the Gaussian fit). This is consistent with that observed for other star-forming galaxies at similar redshifts, and is significantly below the Eddington limit for a radiation pressure regulated starburst.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©:2018 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Keywords: Gravitational lensing; Strong instrumentation: interferometers; Galaxies: structure
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: 10.1093/mnras/sty021
Depositing User: Eprints, Support
Date Deposited: 07 Mar 2018 12:53
Last Modified: 08 Mar 2018 05:34

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