Testing the lognormality of the galaxy and weak lensing convergence distributions from Dark Energy Survey maps

Romer, A K and The DES Collaboration, (2017) Testing the lognormality of the galaxy and weak lensing convergence distributions from Dark Energy Survey maps. Monthly Notices of the Royal Astronomical Society, 466 (2). pp. 1444-1461. ISSN 0035-8711

[img] PDF (This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors, Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.) - Published Version
Available under License All Rights Reserved.

Download (2MB)

Abstract

It is well known that the probability distribution function (PDF) of galaxy density contrast is approximately lognormal; whether the PDF of mass fluctuations derived from weak lensing convergence (kappaWL) is lognormal is less well established. We derive PDFs of the galaxy and projected matter density distributions via the Counts in Cells (CiC) method. We use maps of galaxies and weak lensing convergence produced from the Dark Energy Survey (DES) Science Verification data over 139 deg2. We test whether the underlying density contrast is well described by a lognormal distribution for the galaxies, the convergence and their joint PDF. We confirm that the galaxy density contrast distribution is well modeled by a lognormal PDF convolved with Poisson noise at angular scales from 10'- 40'(corresponding to physical scales of 3-10 Mpc). We note that as kappaWL is a weighted sum of the mass fluctuations along the line of sight, its PDF is expected to be only approximately lognormal. We find that the kappaWL distribution is well modeled by a lognormal PDF convolved with Gaussian shape noise at scales between 10'and 20', with a best-fit chi2/DOF of 1.11 compared to 1.84 for a Gaussian model, corresponding to p-values 0.35 and 0.07 respectively, at a scale of 10'. Above 20'a simple Gaussian model is sufficient. The joint PDF is also reasonably fitted by a bivariate lognormal. As a consistency check we compare the variances derived from the lognormal modelling with those directly measured via CiC. Our methods are validated against maps from the MICE Grand Challenge N-body simulation.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Astronomy Centre
Subjects: Q Science > QB Astronomy
Depositing User: Richard Chambers
Date Deposited: 30 Sep 2016 11:52
Last Modified: 13 May 2017 20:54
URI: http://sro.sussex.ac.uk/id/eprint/63750

View download statistics for this item

📧 Request an update
Project NameSussex Project NumberFunderFunder Ref
UnsetUnsetSTFCUnset