SMA High Angular Resolution Imaging of the Lensed Quasar APM 08279+5255

We present Submillimeter Array observations of the z=3.91 gravitationally lensed broad absorption line quasar APM 08279+5255 which spatially resolve the 1.0 mm (200 μm rest frame) dust continuum emission. At 0.4" resolution, the emission is separated into two components, a stronger, extended one to the northeast (46+/-5 mJy) and a weaker, compact one to the southwest (15+/-2 mJy). We have carried out simulations of the gravitational lensing effect responsible for the two submillimeter components in order to constrain the intrinsic size of the submillimeter continuum emission. Using an elliptical lens potential, the best-fit lensing model yields an intrinsic (projected) diameter of ~80 pc, which is not as compact as the optical/near-infrared (NIR) emission and agrees with previous size estimates of the gas and dust emission in APM 08279+5255. Based on our estimate, we favor a scenario in which the 200 μm (rest frame) emission originates from a warm dust component (T_d=150-220 K) that is mainly heated by the AGN rather than by a starburst. The flux is boosted by a factor of ~90 in our model, consistent with recent estimates for APM 08279+5255.