This page contains background and public outreach material about the weak gravitational lensing analysis of the Hubble Space Telescope COSMOS survey. The work has already received quite a bit of publicity. COSMOS is the largest ever survey with HST, probing the growth of large-scale structure in the universe over cosmic time. The exquisite imaging obtained from space reveals the precise shapes of over half a million distant galaxies. Via the effect of gravitational lensing, these can be used to trace the distribution of otherwise invisible dark matter.

Multimedia stuff

  • High resolution figures and cover artwork of the dark matter map from Nature magazine.

  • Diverse media outlets have reported the dark matter map, and created a range of example material. In particular, a selection of copyright-free videos and images are also available from the ESA press release, and some more images from the NASA press release.

  • Lars Lindberg Christensen at ESA has also produced a red/green stereo version of the mass map, and one with embedded cartoon galaxies. Click on the thumbnail images at the right for higher resolution versions.

  • Powerpoint slides suitable for a university physics department and a public lecture. An audio recording of my public lecture at the American Museum of Natural History.

Raw data products

  • Images direct from the Hubble Space Telescope (and others) are freely available from the COSMOS archive.

  • The projected 2D dark matter map and three 2½D slices are available in .fits image format, an standard in the astronomical community that includes information on the absolute positioning of the image on the sky.

  • The 3D isodensity surface is available in .3ds, .obj and .c4d formats. However, that's only one isosurface. If you really want to start from scratch, the original 3D voxellated data is available in Interactive Data Language (IDL) binary format (plus a routine to help plot it), and as 32 slices in .tiff format. A voxel is just a 3D pixel.

  • Thanks to Julien Lesgourgues, a weak lensing module is available for CosmoMC. It contains the statistical "3D power spectrum" data of the mass distribution, originally published in the Astrophysical Journal. new

Supplementary material

Front cover of Nature magazine, 18th Jan 2007

Stereo image of the 3D mass map

Embedded galaxies are just for fun - NOT REAL DATA!

Last updated by Richard Massey on 2nd May 2008.

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