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Title: Constraining dark energy by combining cluster counts and shear-shear correlations in a weak lensing survey

Abstract

We study the potential of a large future weak lensing survey to constrain dark-energy properties by using both the number counts of detected galaxy clusters (sensitive primarily to density fluctuations on small scales) and tomographic shear-shear correlations (restricted to intermediate and large scales). We use the Fisher matrix formalism, assume a flat universe, and parametrize the equation of state of dark energy by w(a)=w{sub 0}+w{sub a}(1-a), to forecast the expected statistical errors from either observable, and from their combination. We show that the covariance between these two observables is small, and argue that they can therefore be regarded as independent constraints. We find that, when the number counts and the shear-shear correlations (on angular scales l{<=}1000) are combined, a LSST (Large Synoptic Survey Telescope)-like survey can yield statistical errors on {omega}{sub DE}, w{sub 0}, w{sub a} as tight as 0.003, 0.03, 0.1. These values are a factor of 2-25 better than using either observable alone. The results are also about a factor of 2 better than those from combining number counts of galaxy clusters and their power spectrum.

Authors:
 [1];  [2]
  1. Department of Physics, Columbia University, New York, New York 10027 (United States)
  2. Department of Astronomy, Columbia University, New York, New York 10027 (United States)
Publication Date:
OSTI Identifier:
21011042
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevD.75.043010; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CORRELATIONS; COSMOLOGY; DENSITY; EQUATIONS OF STATE; ERRORS; FLUCTUATIONS; GALAXY CLUSTERS; NONLUMINOUS MATTER; POTENTIALS; UNIVERSE

Citation Formats

Fang Wenjuan, and Haiman, Zoltan. Constraining dark energy by combining cluster counts and shear-shear correlations in a weak lensing survey. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.043010.
Fang Wenjuan, & Haiman, Zoltan. Constraining dark energy by combining cluster counts and shear-shear correlations in a weak lensing survey. United States. doi:10.1103/PHYSREVD.75.043010.
Fang Wenjuan, and Haiman, Zoltan. Thu . "Constraining dark energy by combining cluster counts and shear-shear correlations in a weak lensing survey". United States. doi:10.1103/PHYSREVD.75.043010.
@article{osti_21011042,
title = {Constraining dark energy by combining cluster counts and shear-shear correlations in a weak lensing survey},
author = {Fang Wenjuan and Haiman, Zoltan},
abstractNote = {We study the potential of a large future weak lensing survey to constrain dark-energy properties by using both the number counts of detected galaxy clusters (sensitive primarily to density fluctuations on small scales) and tomographic shear-shear correlations (restricted to intermediate and large scales). We use the Fisher matrix formalism, assume a flat universe, and parametrize the equation of state of dark energy by w(a)=w{sub 0}+w{sub a}(1-a), to forecast the expected statistical errors from either observable, and from their combination. We show that the covariance between these two observables is small, and argue that they can therefore be regarded as independent constraints. We find that, when the number counts and the shear-shear correlations (on angular scales l{<=}1000) are combined, a LSST (Large Synoptic Survey Telescope)-like survey can yield statistical errors on {omega}{sub DE}, w{sub 0}, w{sub a} as tight as 0.003, 0.03, 0.1. These values are a factor of 2-25 better than using either observable alone. The results are also about a factor of 2 better than those from combining number counts of galaxy clusters and their power spectrum.},
doi = {10.1103/PHYSREVD.75.043010},
journal = {Physical Review. D, Particles Fields},
number = 4,
volume = 75,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • We measure the redshift evolution of galaxy bias from a magnitude-limited galaxy sample by combining the galaxy density maps and weak lensing shear maps for amore » $$\sim$$116 deg$$^{2}$$ area of the Dark Energy Survey (DES) Science Verification data. This method was first developed in Amara et al. (2012) and later re-examined in a companion paper (Pujol et al., in prep) with rigorous simulation tests and analytical treatment of tomographic measurements. In this work we apply this method to the DES SV data and measure the galaxy bias for a magnitude-limited galaxy sample. We find the galaxy bias and 1$$\sigma$$ error bars in 4 photometric redshift bins to be 1.33$$\pm$$0.18 (z=0.2-0.4), 1.19$$\pm$$0.23 (z=0.4-0.6), 0.99$$\pm$$0.36 ( z=0.6-0.8), and 1.66$$\pm$$0.56 (z=0.8-1.0). These measurements are consistent at the 1-2$$\sigma$$ level with mea- surements on the same dataset using galaxy clustering and cross-correlation of galaxies with CMB lensing. In addition, our method provides the only $$\sigma_8$$-independent constraint among the three. We forward-model the main observational effects using mock galaxy catalogs by including shape noise, photo-z errors and masking effects. We show that our bias measurement from the data is consistent with that expected from simulations. With the forthcoming full DES data set, we expect this method to provide additional constraints on the galaxy bias measurement from more traditional methods. Furthermore, in the process of our measurement, we build up a 3D mass map that allows further exploration of the dark matter distribution and its relation to galaxy evolution.« less
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  • Here, we measure the redshift evolution of galaxy bias for a magnitude-limited galaxy sample by combining the galaxy density maps and weak lensing shear maps for a ~116 deg 2 area of the Dark Energy Survey (DES) Science Verification data. This method was first developed in Amara et al. (2012) and later re-examined in a companion paper (Pujol et al. 2016) with rigorous simulation tests and analytical treatment of tomographic measurements. In this work we apply this method to the DES SV data and measure the galaxy bias for a i < 22.5 galaxy sample. We find the galaxy biasmore » and 1σ error bars in 4 photometric redshift bins to be 1.12±0.19 (z=0.2-0.4), 0.97±0.15 (z=0.4-0.6), 1.38±0.39 (z=0.6-0.8)), and 1.45±0.56 (z=0.8-1.0). These measurements are consistent at the 2σ level with measurements on the same dataset using galaxy clustering and cross-correlation of galaxies with CMB lensing, with most of the redshift bins consistent within the 1{\sigma} error bars. In addition, our method provides the only σ8-independent constraint among the three. We forward-model the main observational effects using mock galaxy catalogs by including shape noise, photo-z errors and masking effects. We show that our bias measurement from the data is consistent with that expected from simulations. With the forthcoming full DES data set, we expect this method to provide additional constraints on the galaxy bias measurement from more traditional methods. Furthermore, in the process of our measurement, we build up a 3D mass map that allows further exploration of the dark matter distribution and its relation to galaxy evolution.« less
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