Weak-lensing Power Spectrum Reconstruction by Counting Galaxies. I. The ABS Method

We propose an analytical method of blind separation (ABS) of cosmic magnification from the intrinsic fluctuations of galaxy number density in the observed galaxy number density distribution. The ABS method utilizes the different dependences of the signal (cosmic magnification) and contamination (gal...

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Bibliographic Details
Published in:The Astrophysical journal 2017-08, Vol.845 (2), p.174
Main Authors: Yang, Xinjuan, Zhang, Jun, Yu, Yu, Zhang, Pengjie
Format: Article
Language:English
Subjects:
Astrophysics
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Clustering
CONFIGURATION
COSMOLOGY
cosmology: observations
Dark energy
dark matter
Density distribution
DISTRIBUTION
Fluctuations
GALAXIES
Galaxy distribution
GRAVITATIONAL LENSES
large-scale structure of universe
Polls & surveys
Power spectra
Reconstruction
Shot noise
SPECTRA
Stars & galaxies
TELESCOPES
UNIVERSE
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Summary:We propose an analytical method of blind separation (ABS) of cosmic magnification from the intrinsic fluctuations of galaxy number density in the observed galaxy number density distribution. The ABS method utilizes the different dependences of the signal (cosmic magnification) and contamination (galaxy intrinsic clustering) on galaxy flux to separate the two. It works directly on the measured cross-galaxy angular power spectra between different flux bins. It determines/reconstructs the lensing power spectrum analytically, without assumptions of galaxy intrinsic clustering and cosmology. It is unbiased in the limit of an infinite number of galaxies. In reality, the lensing reconstruction accuracy depends on survey configurations, galaxy biases, and other complexities due to a finite number of galaxies and the resulting shot noise fluctuations in the cross-galaxy power spectra. We estimate its performance (systematic and statistical errors) in various cases. We find that stage IV dark energy surveys such as Square Kilometre Array and Large Synoptic Survey Telescope are capable of reconstructing the lensing power spectrum at and accurately. This lensing reconstruction only requires counting galaxies and is therefore highly complementary to cosmic shear measurement by the same surveys.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aa7ed4