The Nature of High Redshift Radio Source Hosts

University Of Hawaii, Honolulu

Investigators

Abstract

ABSTRACT AST 0098349 Chambers High redshift radio galaxies (HZRGs) are among the strangest and most distant objects known, there is nothing like them in the universe today. Recent observations suggest that they consist of vast regions of gas and dust illuminated by an aniosotropic quasar beam that becomes visible by scattering like a searchlight in fog. The light scattered by dust is polarized, making these objects a good place to study astronomical dust and the cosmic evolution of the dust content of galaxies. Radio-loud, double-lobed, steep-spectrum quasars (QSRs) are the largest extended objects known at high redshift, and studies of their kinematics, dust content, and stellar populations will provide insight to the formation of massive galaxies. This project will study these high redshift radio source hosts. Two novel observational approaches will be used: (i) Targeted studies of a sample of distant radio sources that have bright (M <13) foreground stars within the isoplanatic patch will be observed with the new generation of adaptive optics instruments on 8-10 meter class telescopes with 50 milliarcsecond resolution. With the adaptive optics systems now available, it is possible to obtain two-dimensional surface brightness profiles and color gradients of the most distant and reddest galaxies. Integral field spectroscopy of the extended emission line regions can be compared with dynamical and dust scattering models. Spatially resolved infrared polarimetry will probe the dust content of these objects and its evolution with redshift. The vast improvement in capability provided by AO with natural guide stars provides a crucial tool to advance the field of radio galaxies in the distant universe. (ii) A wide field optical imaging polarimetry survey that will be the first deep sky survey to search for faint polarized objects. With the prime focus camera on the Subaru 8-meter Japanese National Telescope on Mauna Kea a deep polarimetry survey can reach very faint point sources (greater than 29th magnitude). Observations of three separate 0.5 degree fields, will produce images and a catalog of the linear polarization of more than 100,000 extragalactic objects, including more than 100 faint radio galaxies. These will be cross correlated with known radio, submillimeter, x-ray, and redshift catalogs, and HST morphologies. This wide field imaging polarimetry survey will provide a unique and independent measure of the nature and evolution of the dusty galaxy population at high redshift and measure the impact of dust and reprocessed light on the colors and morphologies of high redshift galaxies and AGN hosts. Funding for this project was provided by the NSF program for Extragalactic Astronomy & Cosmology (AST/EXC). ***