Towards Completing a Large Area ULIRG Survey

Abstract

We present the latest results in our efforts to produce a complete, large sample of Ultraluminous Infrared Galaxies (ULIRGs, L60 > 10^11.4 Lsun for H0=100kms^-1 Mpc^-1, q0=0.5) for use in the study of these objects and their evolution. We have been using an optical/IR colour technique to select those objects most likely to be ULIRGs. 65 of the 198 candidate ULIRGs that do not yet have redshifts were observed. Redshifts were obtained for 51 of these objects, including 8 new ULIRGs and a further three probable ULIRGs with tentative redshifts. The new ULIRGs include one object at z=0.44 (00029-1424), the highest in the survey so far, and at least one new broad-line ULIRG (03156-1706) which appears to lie in a galaxy cluster. We discuss the properties of these objects and their local environments, concluding that three of them have high excitation spectra, and that five show disturbed morphology even in the shallow acquisition images. We also present the redshift measurements of the non-ULIRGs identified in the course of this survey.