We present new Hubble Space Telescope , high-resolution optical imaging of the submm luminous Lyman-break galaxy , Westphal-MMD11 , an interacting starburst at z = 2.979 .
The new imaging data , in conjunction with re-analysis of Keck optical and near-IR spectra , demonstrate MMD11 to be an interacting system of at least three components : a luminous blue source , a fainter blue source , and an extremely red object ( ERO ) with R - K _ { > } \atop { { } ^ { \sim } } 6 .
The separations between components are \sim 8Â kpc ( \Lambda = 0.7 , \Omega _ { M } = 0.3 , h=0.65 ) , similar to some of the local ultra-luminous infrared galaxies ( ULIGs ) .
The lack of obvious AGN in MMD11 , along with the fragmented , early stage merger morphology , suggest a young forming environment .
While we can not unambiguously identify the location of the far-IR emission within the system , analogy to similar ULIGs suggests the ERO as the likely far-IR source .
The > 10 ^ { 12 } L _ { \odot } bolometric luminosity of MMD11 can be predicted reasonably from its rest frame UV properties once all components are taken into account , however this is not typically the case for local galaxies of similar luminosities .
While LBGs as red in g - R and R - K as MMD11 are rare , they can only be found over the restricted 2.7 < z < 3.0 range .
Therefore a substantial number of MMD11- like galaxies ( _ { < } \atop { { } ^ { \sim } } 0.62 arcmin ^ { -2 } ) may exist when integrated over the likely redshift range of SCUBA sources ( z = 1 - 5 ) , suggesting that SCUBA sources should not necessarily be seen as completely orthogonal to optically selected galaxies .