Elliptical Weighted HOLICs for Weak Lensing Shear Measurement part3:Random Count Noise Effect for Image's Moments in Weak Lensing Analysis

Abstract

This is the third paper on the improvements of systematic errors in our weak lensing analysis using an elliptical weight function, called E-HOLICs. In the previous papers we have succeeded in avoiding error which depends on ellipticity of background image. In this paper, we investigate the systematic error which depends on signal to noise ratio of background image. We find that the origin of the error is the random count noise which comes from Poisson noise of sky counts. Random count noise makes additional moments and centroid shift error, and those 1st orders are canceled in averaging, but 2nd orders are not canceled. We derived the equations which corrects these effects in measuring moments and ellipticity of the image and test their validity using simulation image. We find that the systematic error becomes less than 1% in the measured ellipticity for objects with $S/N>3$.

44pages, 20figures, submitted for ApJ

References in corpus (5)

• The Shear TEsting Programme 2: Factors affecting high precision weak lensing analyses
• Bayesian Galaxy Shape Measurement for Weak Lensing Surveys -I. Methodology and a Fast Fitting Algorithm
• Image Analysis for Cosmology: Results from the GREAT10 Galaxy Challenge
• Means of confusion: how pixel noise affects shear estimates for weak gravitational lensing
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• A New Method for PSF correction using the Ellipticity of Re-smeared Artificial Images in Weak Gravitational Lensing Shear Analysis
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