THE CANADA-FRANCE REDSHIFT SURVEY II: Spectroscopic Program; Data for the 0000-00 and 1000+25 Fields

This paper describes the methods used to obtain the spectroscopic data and construct redshift catalogs for the Canada-France deep Redshift Survey (CFRS). The full data set consists of more than one thousand spectra, of objects with 17.5 < I_{AB} < 22.5, obtained from deep multi-slit data with the MARLIN and MOS-SIS spectrographs at the CFHT. The final spectroscopic catalog contains 200 stars, 591 galaxies with secure redshifts in the range 0 < z < 1.3, 6 QSOs, and 146 objects with very uncertain or unknown redshifts, leading to an overall success rate of identification of 85%. Additionally, 67 objects affected by observational problems have been placed in a supplemental list. We describe here the instrumental set up, and the observing procedures used to efficiently gather this large data set. New optimal ways of packing spectra on the detector to significantly increase the multiplexing gain offered by multi-slit spectroscopy are described. Dedicated data reduction procedures have been developed under the IRAF environment to allow for fast and accurate processing. Very strict procedures have been followed to establish a reliable list of final spectroscopic measurements. Fully independent processing of the data has been carried out by three members of the team for each data set associated with a multi-slit mask, and final redshifts were assigned only after the careful comparison of the three independent measurements. A confidence class scheme was established. We strongly emphasize the benefits of such procedures. Finally, we present the spectroscopic data obtained for 303 objects in the 0000-00 and 1000+25 fields. The success rate in spectroscopic identification isComment: 16 uuencoded postcript pages with figures 4,5,8,9 and 12. Other (large) figures available from the authors. Large data table not yet released. Also available at http://www.dao.nrc.ca/DAO/SCIENCE/science.html and coming soon on a CFRS homepage. Accepted June 19, scheduled for the Dec 10 issue of Ap

The CANADA-FRANCE REDSHIFT SURVEY I: Introduction to the Survey, Photometric Catalogs and Surface Brightness Selection Effects

The Canada-France Redshift Survey has been undertaken to provide a large well-defined sample of faint galaxies at high redshift in which the selection criteria match as closely as possible those of samples of nearby galaxies. The survey is designed to have a median redshift of z ~ 0.6 corresponding to a look-back time of half the present age of the Universe for Omega ~ 1. Such a survey can then be used for studying many different aspects of the evolution of galaxies over the interval 0 < z < 1. In this paper we describe the selection of the fields, the multicolor imaging observations and the construction and validation of the photometric catalogs. Particular attention is paid to quantifying the unavoidable selection effects in surface brightness and their impact on the survey is assessed in the context of the properties of known populations of galaxies. The photometric catalogs contain several thousand objects brighter than I_{AB}< 22.5 and are essentially complete for central surface brightnesses as faint as $\mu_{AB}(I)$ $\sim$ 24.5 mag arcsec$^{-2}$. This should be sufficient to include both normal surface brightness galaxies and prototypes of extreme low surface brightness galaxies.Comment: 17 pages, 2 tables, 10 postscript figures (in 2 parts), uses aaspp.sty Also available at http://www.dao.nrc.ca/DAO/SCIENCE/science.html and coming soon on a CFRS homepag

QSO hosts and environments at z=0.9 to 4.2: JHK images with adaptive optics

We have observed nine QSOs with redshifts 0.85 to 4.16 at near-IR wavelengths with the adaptive optics bonnette of the Canada-France-Hawaii telescope. Exposure times ranged from 1500 to 24000s (mostly near 7000s) in J, H, or K bands, with pixels 0.035 arcsec on the sky. The FWHM of the co-added images at the location of the quasars are typically 0.16 arcsec. Including another QSO published previously, we find associated QSO structure in at least eight of ten objects, including the QSO at z = 4.16. The structures seen in all cases include long faint features which appear to be tidal tails. In four cases we have also resolved the QSO host galaxy, but find them to be smooth and symmetrical: future PSF removal may expand this result. Including one object previously reported, of the nine objects with more extended structure, five are radio-loud, and all but one of these appear to be in a dense small group of compact galaxy companions. The radio-quiet objects do not occupy the same dense environments, as seen in the NIR. In this small sample we do not find any apparent trends of these properties with redshift, over the range 0.8 < z < 2.4. The colors of the host galaxies and companions are consistent with young stellar populations at the QSO redshift. Our observations suggest that adaptive optic observations in the visible region will exhibit luminous signatures of the substantial star-formation activity that must be occurring.Comment: 22 pages including 10 tables, plus 11 figures. To appear in A

THE CANADA-FRANCE REDSHIFT SURVEY IX: HST Imaging of High-Redshift Field Galaxies

HST B and I images are presented of 32 CFRS galaxies with secure redshifts in the range 0.5 < z < 1.2. These galaxies exhibit the same range of morphological types as seen locally, i.e., ellipticals, spirals and irregulars. The galaxies look far less regular in the $B$ images (rest-frame ultraviolet) than at longer wavelengths, underlining the fact that optical images of galaxies at still higher redshift should be interpreted with caution. Quantitative analyses of the galaxies yield disk sizes, bulge fractions, and colors for each component. At these redshifts, galaxy disks show clear evidence for surface brightness evolution. The mean rest-frame central surface brightness of the disks of normal late-type galaxies is mu_{AB}(B)=20.2 \pm 0.25 mag arcsec^{-2}, about 1.2 mag brighter than the Freeman (1970) value. Some degree of peculiarity is measurable in 10 (30%) of the galaxies and 4 (13%) show clear signs of interaction/mergers. There are 9 galaxies (30%) dominated by blue compact components. These components, which appear to be related to star formation, occur most often in peculiar/asymmetric galaxies (some of which appear to be interacting), but a few are in otherwise normal galaxies. Thus, of the galaxies bluer than present-day Sb, one-third are "blue nucleated galaxies", and half are late-type galaxies with disks which are significantly brighter than normal galaxies at z=0. Taken together, these two effects must be responsible for much of the observed evolution of the luminosity function of blue galaxies.Comment: uuencoded compressed postscript, 8 pages, 1 table + 5 figures in a separate part. Also available at http://www.astro.utoronto.ca/~lilly/CFRS/ . Accepted for publication in ApJ Letter

Hubble Space Telescope imaging of the CFRS and LDSS redshift surveys - IV. Influence of mergers in the evolution of faint field galaxies from z~1

HST images of a sample of 285 galaxies with measured z from the CFRS and Autofib-LDSS redshift surveys are analysed to derive the evolution of the merger fraction out to z~1. We have performed visual and machine-based merger identifications, as well as counts of bright pairs of galaxies with magnitude differences less than 1.5 mag. We find that the pair fraction increases with z, with up to ~20% of the galaxies being in physical pairs at z~0.75-1. We derive a merger fraction varying with z as (1+z)^{3.2 +/- 0.6}, after correction for line-of-sight contamination, in excellent agreement with the merger fraction derived from the visual classification of mergers for which m = 3.4 +/- 0.6. After correcting for seeing effects on the ground-based selection of survey galaxies, we conclude that the pair fraction evolves as (1+z)^{2.7 +/- 0.6}. This implies that an average L* galaxy will have undergone 0.8 to 1.8 merger events from z=1 to 0, with 0.5 to 1.2 merger events occuring in a 2 Gyr time span at z~0.9. This result is consistent with predictions from semi-analytical models of galaxy formation. From the simple co-addition of the observed luminosities of the galaxies in pairs, physical mergers are computed to lead to a brightening of 0.5 mag for each pair on average, and a boost in star formation rate of a factor of 2, as derived from the average [O II] equivalent widths. Mergers of galaxies are therefore contributing significantly to the evolution of both the luminosity function and luminosity density of the Universe out to z~1.Comment: 14 pages, 6 PS figures included. Accepted for publication in MNRA

The CANADA-FRANCE REDSHIFT SURVEY VI: Evolution of the galaxy luminosity function to z ~ 1

The cosmic evolution of the field galaxy population has been studied out to a redshift of z ~ 1 using a sample of 730 I-band selected galaxies, of which 591 have secure redshifts with median ~ 0.56. The tri-variate luminosity function phi(M,color,z) shows unambiguously that the population evolves and that this evolution is strongly differential with color and, less strongly, with luminosity. The luminosity function of red galaxies shows very little change in either number density or luminosity over the entire redshift range 0 < z < 1. In contrast, the luminosity function of blue galaxies shows substantial evolution at redshifts z > 0.5. By 0.5 < z < 0.75, the blue luminosity function appears to have uniformly brightened by approximately 1 mag. At higher redshifts, the evolution appears to saturate at the brightest magnitudes but continues at fainter levels leading to a steepening of the luminosity function. A significant excess of galaxies relative to the Loveday et al. (1992) local luminosity function is seen at low redshifts z < 0.2 around M(B) ~ -18$ and these galaxies may possibly represent the descendants of the evolving blue population seen at higher redshifts. The changes seen in the luminosity function are also apparent in color-magnitude diagrams constructed at different epochs and in the V/V_max statistic computed as a function of spectral type. Finally, it is argued that the picture of galaxy evolution presented here is consistent with the very much smaller samples of field galaxies that have been selected in other wavebands, and with the results of studies of galaxies selected on the basis of Mg II 2799 absorption.Comment: uuencoded compressed Tex (first part) with 9 uuencoded compressed postscript figures and 2 tables (second part). Also available at http://www.astro.utoronto.ca/~lilly/CFRS/papers.html . Accepted July 17 by ApJ, scheduled for Dec 10 issu

The Canada France Redshift Survey VIII: Evolution of the clustering of galaxies from z~1

We have used the projected two-point correlation function, $w(r_p)$, to investigate the spatial distribution of the 591 galaxies with secure redshifts between $0 \leq z \leq 1.3$ in the five CFRS fields. The slope of the two-point correlation function for the sample as a whole is $\gamma=1.64\pm0.05$, very similar to the local slope, and $\gamma$ is therefore not strongly evolving with redshift. However, the amplitude of the correlation function decreases strongly with increasing redshift, so that at $z\approx0.6$ it is a factor of 10 lower (for $q_0=0.5$) than for a similarly-selected local galaxy population, on scales $0.1<r<2h^{-1}$ Mpc ($q_0=0.5$). As a whole, the CFRS data is adequately represented by $r_0(z=0.53)=1.33 \pm 0.09 h^{-1}$Mpc for $q_0=0.5$, and $r_0(z=0.53)=1.57 \pm 0.09 h^{-1}$Mpc for $q_0=0$. Unless the galaxy population at high redshift is quite different from any population seen locally, an unlikely possibility, then this implies growth of clustering as described by the evolutionary parameter $\epsilon$ to be between $0 < \epsilon < +2$. No difference in the clustering of red and blue galaxies is seen at $z \geq 0.5$, although at lower redshifts, $0.2 \leq z \leq 0.5$, blue galaxies are somewhat less strongly correlated than the redder galaxies, as seen in local samples. This effect could be the equivalent for field galaxies to the Butcher-Oemler effect seen in clusters of galaxies. The cross-correlation functions between red and blue samples have comparable amplitudes to the auto-correlation functions of each. The distribution and power spectrum of pair separations does not indicateComment: 17 pages, 10 figure

Quantitative detection of Exserohilum turcicum in northern leaf blight diseased sorghum and maize leaves

Exserohilum turcicum is the causal agent of northern leaf blight (NLB) disease in sorghum and maize. Early detection of this economically important pathogen is essential for effective disease management to limit yield losses. Here we present a real-time quantitative PCR (qPCR) assay specific for E. turcicum detection and biomass quantification in sorghum and maize. In planta fungal quantification was achieved through amplification of a cytochrome P450 oxidoreductase (cpr1) gene fragment and subsequent normalisation to the host glutathione S-transferase III gene (gst3). The assay could specifically detect E. turcicum in sorghum and maize, but the cpr1 gene fragment was not amplified in non-target fungal pathogens. Application of the assay with NLB diseased sorghum and maize leaf material revealed a significant increase in E. turcicum DNA in leaves with lesion symptoms when compared to leaves with early stage chlorotic fleck symptoms in both hosts. Furthermore, E. turcicum was detected at levels as low as 1 pg in infected sorghum and maize leaves. The assay enables rapid detection and quantification of E. turcicum in sorghum and maize and has useful applications in crop breeding programmes and disease management where cultivar selection and early detection of the pathogen are essential to limit disease spread.The National Research Foundation of South Africahttp://link.springer.com/journal/13313hj2021Forestry and Agricultural Biotechnology Institute (FABI)Plant Production and Soil Scienc