Westphal-MMD 11: An Interacting, Submillimeter Luminous Lyman Break Galaxy

We present new Hubble Space Telescope, high-resolution optical imaging of thesubmm luminous Lyman-break galaxy, Westphal-MMD11, an interacting starburst atz=2.979. The new imaging data, in conjunction with re-analysis of Keck opticaland near-IR spectra, demonstrate MMD11 to be an interacting system of at leastthree components: a luminous blue source, a fainter blue source, and anextremely red object (ERO) with R-K>6. The separations between components are\~8 kpc (Lambda=0.7, Omega_M=0.3, h=0.65), similar to some of the localultra-luminous infrared galaxies (ULIGs). The lack of obvious AGN in MMD11,along with the fragmented, early stage merger morphology, suggest a youngforming environment. While we cannot unambiguously identify the location of thefar-IR emission within the system, analogy to similar ULIGs suggests the ERO asthe likely far-IR source. The >10^{12} L_sun bolometric luminosity of MMD11 canbe predicted reasonably from its rest frame UV properties once all componentsare taken into account, however this is not typically the case for localgalaxies of similar luminosities. While LBGs as red in g-R and R-K as MMD11 arerare, they can only be found over the restricted 2.7 < z < 3.0 range. Thereforea substantial number of MMD11-like galaxies (~<0.62 arcmin^{-2}) may exist whenintegrated over the likely redshift range of SCUBA sources (z=1 -5), suggestingthat SCUBA sources should not necessarily be seen as completely orthogonal tooptically selected galaxies.Comment: 4 pages, 2 figures, updated to match proof