Explore the vast range of titles available.

We review the scientific objectives and the present status cosmic shear studies. We discuss the future prospects and the role cosmic shear could play in a precision cosmology era.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Gravitational lensing effect is a classical prediction of general relativity, but its application to cosmology has been recognized only relatively recently. The technology-driven developments in observational cosmology have spurred gravitational lensing events to the forefront of astronomy and they serve as valuable tools for measuring the cosmological parameters, for probing the dark matter in the universe and for constraining the cosmic scenario of structure formation. We review the recent developments in this field, namely, the time-delay measurements, the masses of galaxies and clusters of galaxies and the cosmic shear.

We describe a new 4096X4096 pixel CCD mosaic camera (MOCAM) available at the prime focus of the Canada-France-Hawaii Telescope (CFHT). The camera is a mosaic of four 2048X2048 Loral frontside-illuminated CCDs with 15 µm pixels, providing a field of view of 14' X14' at a scale of 0.\" 21 pixel¯¹. MOCAM is equipped with B, V, R, and I filters and has demonstrated image quality of 0.\"5-0.\"6 FWHM over the entire field. MOCAM will also be used with the CFHT adaptive optic bonnette and will provide a field of view of 90\" at a scale of 0.\"02 pixel¯¹. MOCAM works within the CFHT Pegasus software environment and observers familiar with this system require no additional training to use this camera effectively. The technical details, the performance, and the first images obtained on the telescope with MOCAM are presented. In particular, we discuss some important improvements with respect to the standard single-CCD FOCAM camera, such as multioutput parallel readout and dynamic antiblooming. We also discuss critical technical issues concerning future wide-field imaging facilities at the CFHT prime focus in light of our experience with MOCAM and our recent experience with the even larger UH 8192X8192 pixel CCD mosaic camera.

Well red A survey of the distant Universe has revealed a much larger population of star-forming galaxies at high cosmological redshift than was previously known. A count of 970 galaxies with redshifts between 1.4 and 5 is a several-fold increase on previous estimates. Knowledge of the number of galaxies present in the Universe at each epoch is an important constraint on models of galaxy evolution. To understand the evolution of galaxies, we need to know as accurately as possible how many galaxies were present in the Universe at different epochs 1 . Galaxies in the young Universe have hitherto mainly been identified using their expected optical colours 2 , 3 , 4 , but this leaves open the possibility that a significant population remains undetected because their colours are the result of a complex mix of stars, gas, dust or active galactic nuclei. Here we report the results of a flux-limited I-band survey of galaxies at look-back times of 9 to 12 billion years. We find 970 galaxies with spectroscopic redshifts between 1.4 and 5. This population is 1.6 to 6.2 times larger than previous estimates 2 , 3 , 4 , with the difference increasing towards brighter magnitudes. Strong ultraviolet continua (in the rest frame of the galaxies) indicate vigorous star formation rates of more than 10–100 solar masses per year. As a consequence, the cosmic star formation rate representing the volume-averaged production of stars is higher than previously measured at redshifts of 3 to 4.

We present new results obtained on the identification and study of high-zgalaxies seen through lensing clusters used as gravitational telescopes. The amplification effect provides a tool to study the spectrophotometric and morphological properties of such galaxies 1 to 3 magnitudes deeper with respect to field surveys. Distant sources with 1 ≤ z ≤ 7 typically are selected close to the critical lines in clusters where the mass distribution is well known, using photometric redshifts computed on a large wavelength interval, as well as lens-inversion criteria. We focus here on the recent results obtained onAC114 and MS1008-1224, two lensing clusters at z = 0.31.[PUBLICATION ABSTRACT]

The Vimos-VLT Deep Survey is a spectroscopic survey aiming at collecting more than 50000 spectra down to a limiting magnitude $I_{\\mathrm{AB}}=24$, and 100000 down to $I_{\\mathrm{AB}}=22.5$, on a total of about 16 deg$^2$ without any color or morphology preselection. We present the $N(z)$ distribution up to $z\\sim 5$, obtained from a purely magnitude-limited sample down to $I_{\\mathrm{AB}}=24$, which is an important input to weak-lensing studies. We discuss the evolution of the galaxy luminosity function up to $z\\sim 2$, which exhibits a very strong increase in the typical galaxy luminosity $\\Delta M^*\\simeq -2.5$ in the U band compared to the local value. Surveys like the VVDS also allow to study the galaxy bias as a function of redshift without assumption about its linearity, an assumption that we find to be violated in some cases. A low bias is found, and the linear bias is shown to increase with redshift.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html