Following the completion of the IRAS Faint Source Survey (FSS), the data were examined for regions having high spacecraft coverage, low cirrus contamination at 60 microns and 100 microns. These regions were further narrowed down to those which had a low surface density of known nearby galaxies. This resulted in the selection of 11 IRAS FSS plates with a total solid angle of 414 deg(2) in both the northern and southern hemispheres. These areas were re-processed through the source extraction and band merging pipelines at lower detection thresholds to obtain a catalog of sources with higher sensitivity than the corresponding data in the FSS. The typical 60 microns 90% completeness level of these reprocessed data is at 110 mJy; the catalog contains many sources as faint as 70-80 mJy at 60 microns. This catalog of sources has been named the IRAS Very Faint Source Survey (VFSS). We are finishing a redshift survey of three fields from the VFSS catalog. Two fields in the south were observed on the Dupont 2.5 m at Las Campanas using both Shectman's wide-field multi-fiber system coupled to the Modular Spectrograph, and with the Modular Spectrograph in long-slit mode. A further field in the north has been observed with the Double Spectrograph on the Palomar 5 m. Redshifts have been determined for over 400 IRAS VFSS galaxies down to F60 = 110 mJy. The distribution peaks at Z ~ 0.07 and extends to Z ~ 0.45. The large-scale stucture within these fields, as well as the evolution of these IRAS galaxies, is presented. This sample is especially useful for testing IRAS galaxy evolution, as it samples not just ultra-luminous galaxies but more ``normal'' IRAS galaxies out to Z ~ 0.2. This survey has considerable overlap in redshift range with deep optical redshift surveys. This presents an alternative to the W([OII] 3727) measure of starburst fraction with lookback time. Two of these fields are scheduled to be observed by the MSX satellite in 1995 at bands centered on ~ 8, 12, 15, 22 microns at much higher spatial resolution than IRAS and at the highest sensitivity attainable by MSX.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1994