Galaxy–galaxy lensing in the VOICE deep survey (original) (raw)
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The Galaxy-Mass Correlation Function Measured from Weak Lensing in the Sloan Digital Sky Survey
The Astronomical Journal, 2004
We present galaxy-galaxy lensing measurements over scales 0.025 to 10 h −1 Mpc in the Sloan Digital Sky Survey. Using a flux-limited sample of 127,001 lens galaxies with spectroscopic redshifts and mean luminosity L ∼ L * and 9,020,388 source galaxies with photometric redshifts, we invert the lensing signal to obtain the galaxy-mass correlation function ξ gm . We find ξ gm is consistent with a power-law, ξ gm = (r/r 0 ) −γ , with best-fit parameters γ = 1.79 ± 0.06 and r 0 = (5.4 ± 0.7)(0.27/Ω m ) 1/γ h −1 Mpc. At fixed separation, the ratio ξ gg /ξ gm = b/r where b is the bias and r is the correlation coefficient. Comparing to the galaxy auto-correlation function for a similarly selected sample of SDSS galaxies, we find that b/r is approximately scale independent over scales 0.2 − 6.7h −1 Mpc, with mean b/r = (1.3 ± 0.2)(Ω m /0.27). We also find no scale dependence in b/r for a volume limited sample of luminous galaxies (−23.0 < M r < −21.5). The mean b/r for this sample is b/r V lim = (2.0 ± 0.7)(Ω m /0.27). We split the lens galaxy sample into subsets based on luminosity, color, spectral type, and velocity dispersion, and see clear trends of the lensing signal with each of these parameters. The amplitude and logarithmic slope of ξ gm increases with galaxy luminosity. For high luminosities (L ∼ 5L * ), ξ gm deviates significantly from a power law. These trends with luminosity also appear in the subsample of red galaxies, which are more strongly clustered than blue galaxies. Subject headings: cosmology:observations -dark matter -gravitational lensing -large-scale structure of the universe
The Astronomical …, 2000
We present measurements of galaxy-galaxy weak lensing from 225 deg2 of early commissioning imaging data from the Sloan Digital Sky Survey (SDSS). We measure a mean tangential shear around a stacked sample of foreground galaxies in three bandpasses (g@, r@, and i@) out to angular radii of 600@@, detecting the shear signal at very high statistical signiÐcance. The shear proÐle is well described by a power law with best-Ðt slope of g \ 0.7È1.1 (95% conÐdence). In the range h \ 10@@È600@@, c T \ c T0 (1@/h)g, the mean tangential shear is approximately 6^1 ] 10~4 in all three bands. A variety of rigorous tests demonstrate the reality of the gravitational lensing signal and conÐrm the uncertainty estimates. In particular, we obtain shear measurements consistent with zero when we rotate the background galaxies by 45¡, replace foreground galaxies with random points, or replace foreground galaxies with bright stars. We interpret our results by assuming that all matter correlated with galaxies belongs to the galaxies. We model the mass distributions of the foreground galaxies, which have a mean luminosity SL (h \ 5@@)T \ 8.7^0.7 ] 109 h~2 1.4^0.12 ] 1010 h~2 1.8^0.14 ] 1010 h~2 as L g{_ , L r{_ , L i{_ , approximately isothermal spheres characterized by a velocity dispersion and a truncation radius s. p v The velocity dispersion is constrained to be km s~1 at 95% conÐdence (145È195 km s~1 p v \ 150È190 including systematic uncertainties), consistent with previous determinations but with smaller error bars. Our detection of shear at large angular radii sets a 95% conÐdence lower limit s [ 140@@, corresponding to a physical radius of 260 h~1 kpc, implying that the dark halos of typical luminous galaxies extend to very large radii. However, it is likely that this is being systematically biased to large value by di †use matter in the halos of groups and clusters of galaxies. We also present a preliminary determination of the galaxy-mass correlation function, Ðnding a correlation length similar to the galaxy autocorrelation function and consistency with a low matter density universe with modest bias.
Astronomical Journal, 2000
We present measurements of galaxy-galaxy weak lensing from 225 deg2 of early commissioning imaging data from the Sloan Digital Sky Survey (SDSS). We measure a mean tangential shear around a stacked sample of foreground galaxies in three bandpasses (g@, r@, and i@) out to angular radii of 600@@, detecting the shear signal at very high statistical signiÐcance. The shear proÐle is well described by a power law with best-Ðt slope of g \ 0.7È1.1 (95% conÐdence). In the range h \ 10@@È600@@, c T \ c T0 (1@/h)g, the mean tangential shear is approximately 6^1 ] 10~4 in all three bands. A variety of rigorous tests demonstrate the reality of the gravitational lensing signal and conÐrm the uncertainty estimates. In particular, we obtain shear measurements consistent with zero when we rotate the background galaxies by 45¡, replace foreground galaxies with random points, or replace foreground galaxies with bright stars. We interpret our results by assuming that all matter correlated with galaxies belongs to the galaxies. We model the mass distributions of the foreground galaxies, which have a mean luminosity SL (h \ 5@@)T \ 8.7^0.7 ] 109 h~2 1.4^0.12 ] 1010 h~2 1.8^0.14 ] 1010 h~2 as L g{_ , L r{_ , L i{_ , approximately isothermal spheres characterized by a velocity dispersion and a truncation radius s. p v The velocity dispersion is constrained to be km s~1 at 95% conÐdence (145È195 km s~1 p v \ 150È190 including systematic uncertainties), consistent with previous determinations but with smaller error bars. Our detection of shear at large angular radii sets a 95% conÐdence lower limit s [ 140@@, corresponding to a physical radius of 260 h~1 kpc, implying that the dark halos of typical luminous galaxies extend to very large radii. However, it is likely that this is being systematically biased to large value by di †use matter in the halos of groups and clusters of galaxies. We also present a preliminary determination of the galaxy-mass correlation function, Ðnding a correlation length similar to the galaxy autocorrelation function and consistency with a low matter density universe with modest bias.
Galaxy–galaxy lensing in the Dark Energy Survey Science Verification data
Monthly Notices of the Royal Astronomical Society
We present galaxy-galaxy lensing results from 139 square degrees of Dark Energy Survey (DES) Science Verification (SV) data. Our lens sample consists of red galaxies, known as redMaGiC, which are specifically selected to have a low photometric redshift error and outlier rate. The lensing measurement has a total signal-to-noise of 29 over scales 0.09 < R < 15 Mpc/h, including all lenses over a wide redshift range 0.2 < z < 0.8. Dividing the lenses into three redshift bins for this constant moving number density sample, we find no evidence for evolution in the halo mass with redshift. We obtain consistent results for the lensing measurement with two independent shear pipelines, ngmix and im3shape. We perform a number of null tests on the shear and photometric redshift catalogs and quantify resulting systematic uncertainties. Covariances from jackknife subsamples of the data are validated with a suite of 50 mock surveys. The results and systematics checks in this work provide a critical input for future cosmological and galaxy evolution studies with the DES data and redMaGiC galaxy samples. We fit a Halo Occupation Distribution (HOD) model, and demonstrate that our data constrains the mean halo mass of the lens galaxies, despite strong degeneracies between individual HOD parameters.
Monthly Notices of the Royal Astronomical Society, 2014
The clustering of galaxies and the matter distribution around them can be described using the halo model complemented with a realistic description of the way galaxies populate dark matter haloes. This has been used successfully to describe statistical properties of samples of galaxies at z < 0.2. Without adjusting any model parameters, we compare the predicted weak lensing signal induced by Luminous Red Galaxies to measurements from SDSS DR7 on much larger scales (up to ∼ 90 h −1 70 Mpc) and at higher redshift (z ∼ 0.4). We find excellent agreement, suggesting that the model captures the main properties of the galaxy-dark matter connection. To extend the comparison to lenses at even higher redshifts we complement the SDSS data with shape measurements from the deeper RCS2, resulting in precise lensing measurements for lenses up to z ∼ 0.6. These measurements are also well described using the same model. Considering solely these weak lensing measurements, we robustly assess that, up to z ∼ 0.6, the number of central galaxies as a function of halo mass is well described by a log-normal distribution with scatter σ log Lc = 0.146 ± 0.011, in agreement with previous independent studies at lower redshift. Our results demonstrate the value of complementing the information about the properties of the (lens) galaxies provided by SDSS with deeper, high-quality imaging data.
Modelling galaxy-galaxy weak lensing with Sloan Digital Sky Survey groups
Monthly Notices of the Royal Astronomical Society, 2009
We use galaxy groups selected from the Sloan Digital Sky Survey (SDSS) together with mass models for individual groups to study the galaxy-galaxy lensing signals expected from galaxies of different luminosities and morphological types. We compare our model predictions with the observational results obtained from the SDSS by for the same samples of galaxies. The observational results are well reproduced in a ΛCDM model based on the WMAP 3-year data, but a ΛCDM model with higher σ 8 , such as the one based on the WMAP 1-year data, significantly over-predicts the galaxy-galaxy lensing signal. We model, separately, the contributions to the galaxy-galaxy lensing signals from different galaxies: central versus satellite, early-type versus late-type, and galaxies in haloes of different masses. We also examine how the predicted galaxy-galaxy lensing signal depends on the shape, density profile, and the location of the central galaxy with respect to its host halo.
Galaxy-Mass Correlations on 10 Mpc Scales in the Deep Lens Survey
2012
We examine the projected correlation of galaxies with mass from small scales (<few hundred kpc) where individual dark matter halos dominate, out to 15 Mpc where correlated large-scale structure dominates. We investigate these profiles as a function of galaxy luminosity and redshift. Selecting 0.8 million galaxies in the Deep Lens Survey, we use photometric redshifts and stacked weak gravitational lensing shear tomography out to radial scales of 1 degree from the centers of foreground galaxies. We detect correlated mass density from multiple halos and large-scale structure at radii larger than the virial radius, and find the first observational evidence for growth in the galaxy-mass correlation on 10 Mpc scales with decreasing redshift and fixed range of luminosity. For a fixed range of redshift, we find a scaling of projected halo mass with rest-frame luminosity similar to previous studies at lower redshift. We control systematic errors in shape measurement and photometric redshift, enforce volume completeness through absolute magnitude cuts, and explore residual sample selection effects via simulations.
Weak-lensing mass estimates of galaxy groups and the line-of-sight contamination
Monthly Notices of the Royal Astronomical Society, 2012
Weak lensing is an important technique to determine the masses of galaxy groups. However, the distortion imprint on the shape of the background galaxies is not only affected by the gravitational field of the main group but by all the mass content along the line-of-sight. Using COSMOS shear mock data we study the shear profile around 165 groups and investigate the level at which the neighbouring groups can enhance or suppress the shear signal from the main halo. The mock data are based on CFHT and Subaru observations, which are used to obtain the photometric redshifts of galaxies in the field and a realistic galaxy density, given by the weak lensing distortion analysis of the observed data. We further use information on the galaxy groups (having a median mass and redshift of M 200 = 3.1 × 10 13 M ⊙ and z = 0.68) from the COSMOS X-ray catalogue of extended sources. The expected gravitational shear field of these groups is calculated assuming that the haloes are described by NFW density profiles, and the total shear is computed by summing the shear over all the lenses. We conclude that, on average, the signal-to-noise for a detection of the main halo is affected by ≈ 15% × n gal /30 with respect to the signal-to-noise the same halo would have if it was isolated in the sky. Groups with neighbours that are close in projected distance ( 1 ′ ) are the most affected, but haloes located at larger angular distances also cause a measurable shear signal. These (angular) distant groups can be interpreted as uncorrelated largescale structure. The average bias in the mass excess estimate of individual groups that is introduced by the external haloes is zero with an rms of ∼ 6 − 72%, depending on the aperture size used. One way to eliminate this bias is by stacking the density profile of several groups. The shear signal introduced by large-scale structure acts as an external source of noise. The averaged uncertainty introduced is σ LSS γt ∼ 0.006 per component for an aperture size of θ ∼ 5 ′ , which corresponds to ∼ 1.8% of the onecomponent intrinsic ellipticity value. This large-scale structure noise error becomes equal to intrinsic ellipticity noise if there are measurements for ∼ 3000 galaxies within a certain aperture, a number that is already achieved by current deep surveys such as COSMOS and, therefore, that should not be ignored.
Weak-lensing analysis of galaxy pairs using CS82 data
Astronomy & Astrophysics, 2019
Here we analyze a sample of close galaxy pairs (relative projected separation < 25 h−1 kpc and relative radial velocities < 350 km s−1) using a weak-lensing analysis based on the Canada-France-Hawaii Telescope Stripe 82 Survey (CS82). We determine halo masses for the total sample of pairs as well as for interacting, red, and higher-luminosity pair subsamples with ∼3σ confidence. The derived lensing signal for the total sample can be fitted either by a Singular Isothermal Sphere (SIS) with σV = 223 ± 24 km s−1 or a Navarro–Frenk–White (NFW) profile with R200 = 0.30 ± 0.03 h−1 Mpc. The pair total masses and total r band luminosities imply an average mass-to-light ratio of ∼200 h M⊙/L⊙. On the other hand, red pairs which include a larger fraction of elliptical galaxies, show a larger mass-to-light ratio of ∼345 h M⊙/L⊙. Derived lensing masses were compared to a proxy of the dynamical mass, obtaining a good correlation. However, there is a large discrepancy between lensing masses ...