Harding E. Smith

The Redshift-Magnitude Relation for Radio Galaxies

We examine the Hubble diagram for radio galaxies and compare radio galaxies and first-ranked cluster galaxies as cosmological test objects. Radio source identification programs are now producing reliable identifications with galaxies as faint as V ≈ 23 and spectroscopy of these objects has already resulted in the discovery of galaxies with redshifts as high as 0. 75, thus there are great expectations for progress in the near future. As in the past, indeterminate corrections, notably luminosity evolution and a possible correlation between radio power and optical luminosity, preclude the determination of qo.

The ISO-IRAS Faint Galaxy Survey: ISOCAM Imaging and Optical Spectroscopy

The goal of the ISO-IRAS Faint Galaxy Survey was to obtain a sample of the most distant, highest luminosity infrared galaxies from the 0.75 million sources in the IRAS Faint Source Survey. The strategy involved providing a large sample of sources, selected to be faint, high-luminosity (hence highredshift) infrared galaxies, that ISO could select from to fill short (∼ 12 mins) schedule gaps. The initial observing program involved CAM LW10 imaging at 12μm plus PHT 90μm photometry (PHT22) in order to obtain SED information and to provide good positions and reliable identifications for optical spectroscopy and other follow-up observations.

Lyman Alpha Absorption Systems and the Evolution of Disk Galaxies

The strong self-damped Lyman α absorption systems in high redshift QSOs show characteristics which lead us to associate them with the high-redshift precursors of current gaseous disk galaxies. Imaging observations for Lyman α emission have failed to detect these systems. We set a limiting star formation rate in these systems of approximately 1-4 M ⊙ yr-1. With small but observationally allowable amounts of dust the limit may be about ten times larger. We suggest that disk-like structures form early, within about 1 Gyr of the turnaround epoch, but that rapid star formation does not begin until later epochs, or occurs in episodic fashion.