An Obscured Radio Galaxy at High Redshift
Abstract
Perhaps as many as 10% of high-redshift radio galaxy (z>2) candidates that are selected using an ultrasteep radio spectrum criterion fail to show optical emission (continuum, lines) in deep Keck exposures. Their parent objects are only detected in the near-IR and are probably heavily obscured and/or at very high redshift. To search for signatures of dust and help constrain the nature and redshifts of these ``no-z'' radio galaxies, we have conducted a program of submillimeter and millimeter observations. Here we report the first results of a detailed study of one of these objects, WN J0305+3525. It appears associated with a small group of K~21-22 objects and is strongly detected at both 850 μm and 1.25 mm. On the basis of its faint K-band magnitude, spectral energy distribution, and other evidence, we estimate that the radio galaxy is probably at a redshift z~=3+/-1. This would make WN J0305+3525 a radio-loud hyperluminous infrared galaxy (LFIR~1013 Lsolar) similar to, but more obscured than, other dusty radio galaxies in this redshift range. This, together with the absence of Lyα emission and compact (θ<~1.9") radio structure, suggests that WN J0305+3525 is embedded in a very dense, dusty medium and is probably at an early stage of its formation.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2003
- DOI:
- 10.1086/367689
- arXiv:
- arXiv:astro-ph/0302432
- Bibcode:
- 2003ApJ...582L..71R
- Keywords:
-
- Galaxies: Evolution;
- Galaxies: High-Redshift;
- Radio Continuum: Galaxies;
- Submillimeter;
- Astrophysics
- E-Print:
- 13 Pages LaTeX, including 3 Postscript figures