We present a list of 13 candidate gravitationally lensed submillimeter galaxies ( SMGs ) from 95 deg ^ { 2 } of the Herschel Multi-tiered Extragalactic Survey , a surface density of 0.14 \pm 0.04 deg ^ { -2 } .
The selected sources have 500 \micron flux densities ( S _ { 500 } ) greater than 100 mJy .
Gravitational lensing is confirmed by follow-up observations in 9 of the 13 systems ( 70 \% ) , and the lensing status of the four remaining sources is undetermined .
We also present a supplementary sample of 29 ( 0.31 \pm 0.06 deg ^ { -2 } ) gravitationally lensed SMG candidates with S _ { 500 } = 80 –100 mJy , which are expected to contain a higher fraction of interlopers than the primary candidates .
The number counts of the candidate lensed galaxies are consistent with a simple statistical model of the lensing rate , which uses a foreground matter distribution , the intrinsic SMG number counts , and an assumed SMG redshift distribution .
The model predicts that 32–74 % of our S _ { 500 } \geq 100 mJy candidates are strongly gravitationally lensed ( \mu \geq 2 ) , with the brightest sources being the most robust ; this is consistent with the observational data .
Our statistical model also predicts that , on average , lensed galaxies with S _ { 500 } = 100 mJy are magnified by factors of \sim 9 , with apparently brighter galaxies having progressively higher average magnification , due to the shape of the intrinsic number counts .
65 % of the sources are expected to have intrinsic 500 \micron flux densities less than 30 mJy .
Thus , samples of strongly gravitationally lensed SMGs , such as those presented here , probe below the nominal Herschel detection limit at 500 \micron .
They are good targets for the detailed study of the physical conditions in distant dusty , star-forming galaxies , due to the lensing magnification , which can lead to spatial resolutions of \sim 0.01 \arcsec in the source plane .