First Cosmic Shear Results from the Canada-France-Hawaii Telescope Wide Synoptic Legacy Survey

We present the first measurements of the weak gravitational lensing signal induced by the large-scale mass distribution in the universe from data obtained as part of the ongoing Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). The data used in this analysis are from the Wide Synoptic Survey, which aims to image � 170 deg 2 in five filters. We have analyzed an effective area of � 22 deg 2 (31 pointings) of i 0 data spread over two of the three survey fields. These data are of excellent quality, and the results bode well for the remainder of the survey: we do not detect a significant ‘‘B’’ mode, suggesting that residual systematics are negligible at the current level of accuracy. Assuming a cold dark matter model and marginalizing over the Hubble parameter h 2½ 0:6; 0:8� , the source redshift distribution, and systematics, we constrain � 8, the amplitude of the matter power spectrum. At a fiducial matter density m ¼ 0:3 we find � 8 ¼ 0:85 � 0:06. This estimate is in excellent agreement with previous studies. A combination of our results with those from the Deep component of the CFHTLS enables us to place a constraint on a constant equation of state for the dark energy, based on cosmic shear data alone. We find that w0 < � 0:8 at 68% confidence. Subject headingg cosmology: observations — dark matter — gravitational lensing Online material: color figures

[1]  T. Broadhurst,et al.  A Method for Weak Lensing Observations , 1994, astro-ph/9411005.

[2]  Martin White,et al.  Large-Scale Systematic Signals in Weak Lensing Surveys , 2004 .

[3]  Patrick Simon,et al.  The covariance of cosmic shear correlation functions and cosmological parameter estimates using redshift information , 2003 .

[4]  G. M. Bernstein,et al.  Shapes and Shears, Stars and Smears: Optimal Measurements for Weak Lensing , 2001 .

[5]  Uros Seljak,et al.  Shear calibration biases in weak-lensing surveys , 2003, astro-ph/0301054.

[6]  H. Hoekstra,et al.  Hubble Space Telescope Weak-Lensing Study of the z=0.83 Cluster MS 1054–03 , 1999, astro-ph/9910487.

[7]  E. Bertin,et al.  SExtractor: Software for source extraction , 1996 .

[8]  Edinburgh,et al.  Joint cosmic shear measurements with the Keck and William Herschel Telescopes , 2002, astro-ph/0203134.

[9]  Puragra Guhathakurta,et al.  The clustering of faint galaxies , 1991 .

[10]  D. Schlegel,et al.  Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds , 1997, astro-ph/9710327.

[11]  David M. Wittman,et al.  Detection of weak gravitational lensing distortions of distant galaxies by cosmic dark matter at large scales , 2000, Nature.

[12]  Constraints on Omega_m and sigma_8 from weak lensing in RCS fields , 2002, astro-ph/0204295.

[13]  H. Hoekstra,et al.  Weak Lensing Analysis of Cl 1358+62 Using Hubble Space Telescope Observations , 1998 .

[14]  Cambridge,et al.  Detection of weak gravitational lensing by large-scale structure , 2000 .

[15]  Gary Bernstein,et al.  Dark Energy Constraints from the CTIO Lensing Survey , 2006 .

[16]  J. Peacock,et al.  Stable clustering, the halo model and non-linear cosmological power spectra , 2002, astro-ph/0207664.

[17]  H. Dahle,et al.  Galaxy-Galaxy Lensing in the Hubble Deep Field: The Halo Tully-Fisher Relation at Intermediate Redshift , 1997, astro-ph/9711341.

[18]  J. Kneib,et al.  Weak-Lensing Mass Distributions for 24 X-Ray Abell Clusters , 2003, astro-ph/0310009.

[19]  R. Blandford,et al.  Weak Gravitational Lensing by Galaxies , 1996 .

[20]  Properties of Galaxy Dark Matter Halos from Weak Lensing , 2003, astro-ph/0306515.

[21]  Joint cosmological parameters forecast from CFHTLS-cosmic shear and CMB data , 2004, astro-ph/0404317.

[22]  Henk Hoekstra.  The effect of imperfect models of point spread function anisotropy on cosmic shear measurements , 2004 .

[23]  Weak lensing and CMB: Parameter forecasts including a running spectral index , 2003, astro-ph/0308446.

[24]  G. A. Luppino,et al.  Detection of Weak Lensing by a Cluster of Galaxies at z = 0.83 , 1996, astro-ph/9601194.

[25]  S. Maddox,et al.  Weak Gravitational Lensing by a Sample of X-Ray Luminous Clusters of Galaxies. I. The Data Set , 2002 .

[26]  T. Theuns,et al.  Discriminating Weak Lensing from Intrinsic Spin Correlations Using the Curl-Gradient Decomposition , 2000, astro-ph/0012336.

[27]  A. Réfrégier.  Shapelets: I. a method for image analysis , 2001, astro-ph/0105178.

[28]  Dependence of the non-linear mass power spectrum on the equation of state of dark energy , 2005, astro-ph/0505565.

[29]  Dealing with systematics in cosmic shear studies: New results from the VIRMOS-Descart survey , 2004, astro-ph/0406468.

[30]  Peter Schneider,et al.  A NEW MEASURE FOR COSMIC SHEAR , 1998 .

[31]  Bonn,et al.  Analysis of two-point statistics of cosmic shear - I. Estimators and covariances , 2002, astro-ph/0206182.

[32]  S. J. Dodds,et al.  Non-linear evolution of cosmological power spectra , 1996 .

[33]  P. Hall,et al.  A Measurement of Weak Lensing by Large-Scale Structure in Red-Sequence Cluster Survey Fields , 2002, astro-ph/0202285.

[34]  Wayne Hu,et al.  � 1999. The American Astronomical Society. All rights reserved. Printed in U.S.A. POWER SPECTRUM TOMOGRAPHY WITH WEAK LENSING , 1999 .

[35]  Uros Seljak,et al.  Cosmological Model Predictions for Weak Lensing: Linear and Nonlinear Regimes , 1996, astro-ph/9611077.

[36]  H. Hoekstra,et al.  Constraints on Ωm and σ8 from Weak Lensing in Red-Sequence Cluster Survey Fields , 2002 .

[37]  Yannick Mellier,et al.  How accurately can we measure weak gravitational shear , 2001 .

[38]  H. Hoekstra,et al.  Joint cosmic microwave background and weak lensing analysis: constraints on cosmological parameters. , 2003, Physical review letters.

[39]  MEASURING GALAXY MASSES USING GALAXY-GALAXY GRAVITATIONAL LENSING , 1995, astro-ph/9503073.

[40]  A. Hamilton,et al.  Reconstructing the primordial spectrum of fluctuations of the universe from the observed nonlinear clustering of galaxies , 1991 .

[41]  D. Schlegel,et al.  Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds , 1998 .

[42]  Konrad Kuijken,et al.  HST large-field weak lensing analysis of MS 2053-04 : study of the mass distribution and mass-to-light ratio of X-ray luminous clusters at 0.22 , 2002 .

[43]  M. Bartelmann,et al.  Weak gravitational lensing , 2016, Scholarpedia.

[44]  P. Schneider,et al.  B-modes in cosmic shear from source redshift clustering , 2002 .

[45]  Marc Davis,et al.  Science Objectives and Early Results of the DEEP2 Redshift Survey , 2002, SPIE Astronomical Telescopes + Instrumentation.

[46]  J. P. Huchra,et al.  Final Results from the Hubble Space Telescope Key Project to Measure the Hubble Constant , 1998, astro-ph/9801080.

[47]  Puragra Guhathakurta,et al.  Discoveries and Research Prospects from 6- to 10-Meter-Class Telescopes II , 2003 .

[48]  A. Fernandez-Soto,et al.  A New Catalog of Photometric Redshifts in the Hubble Deep Field , 1999 .

[49]  Numerical simulations of weak lensing measurements , 2000, astro-ph/0007023.

[50]  Neutrino mass and dark energy from weak lensing. , 2002, Physical review letters.

[51]  G. Bernstein,et al.  Weak-Lensing Results from the 75 Square Degree Cerro Tololo Inter-American Observatory Survey , 2003 .

[52]  Y. Mellier,et al.  Gravity and Nongravity Modes in the VIRMOS-DESCART Weak-Lensing Survey , 2001, astro-ph/0109182.

[53]  Weak Lensing Results from the 75 Square Degree CTIO Survey , 2002, astro-ph/0210604.