Thousand square degree run

This directory contains simulated weak lensing maps made from ray tracing through N-body simulations of structure formation. Multiple runs of the same cosmological model, started with different random number seeds, are used to build up 1000 square degrees of lensing sky, in (independent) 3x3 degree chunks.

Basic data

The basic data consists of a series of maps for our model which is of the spatially flat Lambda CDM family with a scale-invariant initial power spectrum. The matter density is 28% of the critical density and the baryon density is 4.9% of critical. We assume the Hubble constant is 70km/s/Mpc and the normalization has sigma8=0.9.

In all seven independent simulations of a 200Mpc/h cubical box were run, each with 384^3 equal mass (~10^10Msun/h) dark matter particles. The force softening was of the spline form with a Plummer equivalent epsilon of 18kpc/h (constant in comoving coordinates). The full phase space distribution was dumped every 50Mpc/h along the line-of-sight. For each box 16 maps were produced by ray tracing with different orientations through the lightcone produced by the series of outputs.

All of the files are in FITS format and contain arrays of two shear components and convergences covering a 3x3 degree field of view. Each FITS file contains the data for one field in a 3xNxN array where N=1024 pixels.

The maps have been made for 4 source redshift distributions. For simplicity we take p(z)~z^2 Exp[-(z/z0)^b] with b=1.5 or 1.0 and =1.0 or 1.5. The source distributions are labelled as:

To simplify downloads and file management, the maps for distribution 1 have been grouped into (gzipped) tar files called shear.N.01.tgz where N=11-17.

Auxilliary data

Galaxy catalogues, containing angular and redshift position, convergence and shear for a "realistic" source distribution, are available. There are 7 entries per galaxy and roughly 200 galaxies per square arcminute as explained in the FITS headers. These galaxies are meant to be used for testing shot-noise or shear assignment, the clustering properties are not terribly realistic.

For people interested in finding clusters, 3D group catalogues have been produced. The files contain the cluster information for each field. Each group has 1 row and the columns are x and y pixel position for the most bound particle in the group, M_{200} in Msun/h, comoving distance in Mpc/h, line-of-sight velocity as a distance offset (also in Mpc/h), redshift and FoF group mass.
Beware of array indexing conventions between C/Fortran/IDL etc. You may need to transpose the maps to get correspondance with the files.

Index of Lensing/Thousand

NameSize (MB)Last modified
checksum_24Aug06.dat 02006/08/24
groups.011.tgz 52006/09/07
groups.012.tgz 52006/09/07
shear.011.01.tgz 1782004/11/18
shear.012.01.tgz 1782004/11/18
shear.013.01.tgz 1782004/11/18
shear.014.01.tgz 1782004/11/18
shear.015.01.tgz 1782004/11/18
shear.016.01.tgz 1782004/11/18
shear.017.01.tgz 1782004/11/18

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Last modified Thu Sep 7 07:46:20 2006