MultiDarkLens is a project to perform, analyse and provide to the scientific community high quality weak lensing simulations using the MultiDark cosmological N-body simulations (www.multidark.org).
The BigMultiDark simulation used here is described in Klypin et al. 2014 (arXiv:1411.4001). The simulation was run with the following Planck LCDM cosmological parameters 𝛺M = 0.307, 𝛺b = 0.048, 𝜎8 = 0.82, ns = 0.96, h=0.6777. The box size is 2500 Mpc/h, and it contains 38403 particles.
The light-cones have the geometry of the w1 and w4 fields from the VIPERS collaboration with a pixel resolution of 6 arcsec by side.
The figure below displays a schematic representation of the light-cone construction from the simulation. The slices in colour show the portion
of the matter extracted from each simulation snapshot with comoving distance
between Di and Di+1, within the aperture of the field of
view. Given Di and Di+1 we define the lens redshift at their half distance zl,i = z[(Di + Di+1)/2] and the source redshift zs,i = z[Di+1].
The ray-shooting is done with the gravitational lensing code GLAMER (Metcalf & Petkova 2014, MNRAS, 445, 1942; Petkova, Metcalf & Giocoli, 2014, MNRAS, 445, 1954).
In each realisation of the field we have created a set of 24 lens planes which
allowed us to construct 24 sets of convergence maps with natural sources at the corresponding redshifts:
|z=||2.297 (1)||2.119 (2)||1.955 (3)||1.802 (4)||1.66 (5)||1.527 (6)||1.403 (7)||1.287 (8)|
|1.178 (9)||1.075 (10)||0.9774 (11)||0.8854 (12)||0.7982 (13)||0.7154 (14)||0.6365 (15)||0.5612 (16)|
|0.4892 (17)||0.4201 (18)||0.3538 (19)||0.2899 (20)||0.2282 (21)||0.1686 (22)||0.1108 (23)||0.05465 (24)|
The large number of stored snapshots has allowed us to construct shear catalogues of random galaxies within the past light-cones using a reference source redshift distribution as in the following figure:
in particular the dotted line show the source redshift distribution from CFHTLens, and the histogram the distribution obtained sampling one light-cone realizations of the w1 field. For each light-cone realization we make publicly available the catalogues following the CFHTLens redshift distribution. The various columns contain:
γ, κ, γ1, γ2, μ, ra [arcmin], dec [arcmin], redshift, comoving distance [Mpc/h];
coordinates are in the flat-sky approximation.
We underline that in case you need a catalogue of lensing quantities for a different source redshift distribution you can write an email to:
specifying the light-cone (w1 or w4) and the corresponding number of realizations. Do not forget to attach to your email the source redshift distribution file, containing z and n(z), normalized to your total number of galaxies in the field in unit of arcmin2.
w1 (VIPERS) field (54 different light-cone realizations):
w4 (VIPERS) field (99 different light-cone realizations):
The BigMDPL simulation has been performed on the Super- MUC supercomputer at the Leibniz-Rechenzentrum (LRZ) in Munich, using the computing resources awarded to the PRACE project number 2012060963. CG thanks CNES for financial support. CG and RBM’s research is part of the project GLENCO, funded under the European Seventh Framework Programme, Ideas, Grant Agreement n. 259349. GY acknowledges support from MINECO (Spain) under re- search grants AYA2012-31101 and FPA2012-34694 and Con- solider Ingenio SyeC CSD2007-0050 CG, EJ and Sdlt ac- knowledge the support of the OCEVU Labex (ANR-11-LABX-0060) and the A*MIDEX pro ject (ANR-11-IDEX- 0001-02) funded by the “Investissements d’Avenir” French government program managed by the ANR. We thank the Red Española de Supercomputación for granting us com- puting time in the Marenostrum Supercomputer at the BSC- CNS where part of the analyses presented in this paper have been performed.