We perform lens modelling and source reconstruction of Submillimeter Array ( SMA ) data for a sample of 12 strongly lensed galaxies selected at 500 \micron 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 5 \sigma .
We also fit the reconstructed source surface brightness with an elliptical Gaussian model .
We derive a median value r _ { eff } \sim 1.77 kpc and a median Gaussian full width at half maximum \sim 1.47 kpc .
After correction for magnification , our sources have intrinsic star formation rates SFR \sim 900 - 3500 { M } _ { \sun } { yr } ^ { -1 } , resulting in a median star formation rate surface density \Sigma _ { SFR } \sim 132 { M } _ { \sun } { yr } ^ { -1 } kpc ^ { -2 } ( or \sim 218 { M } _ { \sun } { 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 .