Submillimeter observations of the ultraluminous broad absorption line quasar APM 08279+5255

With an inferred bolometric luminosity of 5 x 10(15) L., the recently ident ified z = 3.87, broad absorption line quasar APM 08279+5255 is apparently t he most luminous object currently known. Since half of its prodigious emiss ion occurs in the infrared, APM 08279+5255 also represents the most extreme example of an ultraluminous infrared galaxy. Here we present new submillim eter observations of this phenomenal object; while indicating that a vast q uantity of dust is present, these data prove to be incompatible with the cu rrent models of emission and reprocessing mechanisms in ultraluminous syste ms. The influence of gravitational lensing on these models is considered, a nd we find that while the emission from the central continuum-emitting regi on may be significantly enhanced, lensing-induced magnification cannot easi ly reconcile the models with the observations. We conclude that further mod eling, including the effects of any differential magnification, is required to explain the observed emission from APM 08279+5255.