Weak Lensing with Sizes, Magnitudes and Shapes

Abstract

Weak lensing can be observed through a number of effects on the images of distant galaxies; their shapes are sheared, their sizes and fluxes (magnitudes) are magnified and their positions on the sky are modified by the lensing field. Galaxy shapes probe the shear field whilst size, magnitude and number density probe the convergence field. Both contain cosmological information. In this paper we are concerned with the magnification of the size and magnitude of individual galaxies as a probe of cosmic convergence. We develop a Bayesian approach for inferring the convergence field from a measured size, magnitude and redshift and demonstrate that the inference on convergence requires detailed knowledge of the joint distribution of intrinsic sizes and magnitudes. We build a simple parameterised model for the size-magnitude distribution and estimate this distribution for CFHTLenS galaxies. In light of the measured distribution, we show that the typical dispersion on convergence estimation is ~0.8, compared to ~0.38 for shear. We discuss the possibility of physical systematics for magnification (similar to intrinsic alignments for shear) and compute the expected gains in the Dark Energy Figure-of-Merit (FoM) from combining magnification with shear for different scenarios regarding systematics: when accounting for intrinsic alignments but no systematics on the magnification signal, including magnification could improve the FoM by upto a factor of ~2.5, whilst when accounting for physical systematics in both shear and magnification we anticipate a gain between ~25% and ~65%. In addition to the statistical gains, the fact that cosmic shear and magnification are subject to different systematics makes magnification an attractive complement to any cosmic shear analysis.

15 pages, 5 figures, accepted by MNRAS

References in corpus (15)

• Dark energy constraints from cosmic shear power spectra: impact of intrinsic alignments on photometric redshift requirements
• Intrinsic galaxy alignments from the 2SLAQ and SDSS surveys: luminosity and redshift scalings and implications for weak lensing surveys
• Bayesian Galaxy Shape Measurement for Weak Lensing Surveys -I. Methodology and a Fast Fitting Algorithm
• Constraints on intrinsic alignment contamination of weak lensing surveys using the MegaZ-LRG sample
• Intrinsic alignments of SDSS-III BOSS LOWZ sample galaxies
• Bayesian Galaxy Shape Measurement for Weak Lensing Surveys -II. Application to Simulations
• The Dependence of the Mass Assembly History of Cold Dark Matter Halos on Environment
• The removal of shear-ellipticity correlations from the cosmic shear signal via nulling techniques
• The Gravitational Shear--Intrinsic Ellipticity Correlation Functions of Luminous Red Galaxies in Observation and in the $\Lambda$CDM Model
• Constraints on the Alignment of Galaxies in Galaxy Clusters from $\sim$14,000 Spectroscopic Members
• Larger sizes of massive quiescent early-type galaxies in clusters than in the field at 0.8 < z < 1.5
• Evidence for a correlation between the sizes of quiescent galaxies and local environment to z ~ 2
• The stellar mass-size relation for the most isolated galaxies in the local Universe
• The effect of the environment on the stellar mass - size relation of present-day galaxies
• On the complementarity of galaxy clustering with cosmic shear and flux magnification

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