Westphal-mmd 11: an Interacting, Submillimeter Luminous Lyman Break Galaxy

We present new Hubble Space Telescope, high-resolution optical imaging of the submillimeter luminous Lyman break galaxy (LBG), Westphal-MMD 11, an interacting starburst at . The new imaging data, in conjunction z p 2.979 with reanalysis of Keck optical and near-IR spectra, demonstrate MMD 11 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 . The separations between components are ∼8 kpc ( , , ), similar to some of K 6 L p 0.7 Q p 0.3 h p 0.65 M the local ultraluminous infrared galaxies (ULIGs). The lack of obvious active galactic nucleus in MMD 11, along with the fragmented, early-stage merger morphology, suggest a young forming environment. While we cannot 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 greater than bolometric luminosity of MMD 11 can be predicted 12 10 L, 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 MMD 11 are rare, they can only be found over the restricted range. Therefore, a substantial number of MMD 11–like 2.7 ! z ! 3.0 galaxies ( 0.62 arcmin ) may exist when integrated over the likely redshift range of Submillimeter Common-User Bolometric Array (SCUBA) sources ( ), suggesting that SCUBA sources should not necessarily be seen as z p 1–5 completely orthogonal to optically selected galaxies. Subject headings: cosmology: observations — galaxies: evolution — galaxies: formation — galaxies: starburst