Hawaii 167 and Q0059-2735: Heavily dust-enshrouded young QSOs

Using the OH-airglow suppressor spectrograph at the University of Hawaii 2.2 m telescope and the CGS4 spectrometer at the United Kingdom Infrared Telescope, we have found exceptionally large Balmer decrements in two unusual high-z QSOs, Hawaii 167 (z=2.36, H alpha/H beta=13) and Q0059-2735 (z=1.59, H alpha/H beta=7.6), the latter being a so-called low-ionization broad absorption line QSO (BALQSO). We argue that these objects are young QSOs heavily enshrouded by dust. In fact, the internal reddening might be so large as to completely extinguish the QSO light in the restframe UV, allowing us to see the underlying stellar population. Our possible detection of the 4000 Angstrom break in Hawaii 167 supports this idea. Its small amplitude indicates a very young age for the population, similar to 15 Myrs. To explain the properties of these QSOs, we propose a model in which a young QSO is surrounded by a shell of young massive stars mixed with significant amounts of dust. We predict that as the QSO emerges from this dust cocoon, it will eventually take on the appearance of a normal BALQSO. (C) 1996 American Astronomical Society.