Discovery of an Extremely Red Galaxy at z=0.65 with Dusty Star Formation and Nuclear Activity

Abstract

In the course of the follow-up multiwavelength study of a deep radio survey, we have discovered that the millijansky radio source PDF J011423 is a low-redshift (z=0.65) extremely red galaxy (ERG) with K=15.3, R-K=5.8, and J-K=3.1. Optical, infrared, and radio photometry, together with optical and near-infrared spectroscopy, reveal a heavily obscured galaxy (A_V=5-6, from the observed Balmer decrement) undergoing vigorous star formation and presenting an active galactic nucleus. PDF J011423 is a representative member of the dusty ERG population, providing a local counterpart for studying more distant ERGs. Based on observations with the Infrared Space Observatory, Australia Telescope Compact Array, Anglo-Australian Telescope, Cerro Tololo Inter-American Observatory, and the European Southern Observatory (program 266.A-5633).