Testing the lognormality of the galaxy and weak lensing convergence distributions from Dark Energy Survey maps
May 6, 201618 pages
Published in:
- Mon.Not.Roy.Astron.Soc. 466 (2017) 2, 1444-1461
- Published: Aug 30, 2016
e-Print:
- 1605.02036 [astro-ph.CO]
Report number:
- FERMILAB-PUB-16-161-AE
Experiments:
Citations per year
Abstract: (Oxford University Press)
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 (κ_WL) 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 Science Verification data over 139 deg^2. 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 modelled by a lognormal PDF convolved with Poisson noise at angular scales from 10 to 40 arcmin (corresponding to physical scales of 3–10 Mpc). We note that as κ_WL 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 κ_WL distribution is well modelled by a lognormal PDF convolved with Gaussian shape noise at scales between 10 and 20 arcmin, with a best-fitting χ^2/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 arcmin. Above 20 arcmin 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.Note:
- 17 pages, 14 figures, submitted to MNRAS
- gravitational lensing: weak
- cosmology: observations
- large-scale structure of Universe
References(63)
Figures(19)