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

Enia, A., Negrello, M. ORCID:, Gurwell, M., Dye, S., Rodighiero, G., Massardi, M., De Zotti, G., Franceschini, A., Cooray, A., van der Werf, P., Birkinshaw, M., Michalowski, 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) , 3467–3484. 10.1093/mnras/sty021

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We perform lens modelling and source reconstruction of Submillimeter 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 dataset 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 star formation rate surface density ΣSFR ∼ 132 M⊙yr−1 kpc−2 (or ∼218 M⊙yr−1 kpc−2 for the Gaussian fit). This is consistent with what 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
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QB Astronomy
Publisher: Oxford University Press
ISSN: 0035-8711
Date of First Compliant Deposit: 10 January 2018
Date of Acceptance: 29 December 2017
Last Modified: 18 Nov 2023 17:06

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