An Obscured Radio Galaxy at High Redshift

Perhaps as many as 10% of high redshift radio galaxy (HzRG; z > 2) candidatesthat are selected using an Ultra Steep radio Spectrum (USS) criterion fail toshow optical emission (continuum, lines) in deep Keck exposures. Their parentobjects are only detected in the near-IR and are probably heavily obscuredand/or at very high redshift. To search for signatures of dust and helpconstrain the nature and redshifts of these ``no-z'' radio galaxies, we haveconducted a program of submillimeter and millimeter observations. Here wereport the first results of a detailed study of one of these objects, WNJ0305+3525. WN J0305+3525 appears associated with a small group of K ~ 21 - 22 objectsand is strongly detected at both 850 micron and 1.25 mm. On the basis of itsfaint K-band magnitude, spectral energy distribution (SED) and other evidencewe estimate that the radio galaxy is probably at a redshift z = 3 +/- 1. Thiswould make WN J0305+3525 a radio-loud Hyper Luminous Infrared Galaxy (LFIR ~10^13 Lsun) similar to, but more obscured than, other dusty radio galaxies inthis redshift range. This, together with the absence of Lya emission andcompact (theta < 1.9") radio structure, suggests that WN J0305+3525 is embeddedin a very dense, dusty medium and is probably at an early stage of itsformation.Comment: 13 Pages LaTeX, including 3 Postscript figure