Archive for March 27, 2013

The Universe through a lens, darkly…

Posted in The Universe and Stuff with tags , , on March 27, 2013 by telescoper

Just time to post this neat picture I found on the BBC Website this morning:


Although these images were obtained using measurements of the cosmic microwave background made by Planck, they are not themselves maps of the radiation field itself. As photons produced in the early Universe travel through the Universe towards the observer, they are deflected by the gravitational field of intervening clumps of matter; this is called gravitational lensing. With a bit of effort this effect can be “inverted” to reveal the distribution of matter traversed by CMB photons, or at least a projection of that distribution along the line of sight. The good thing about this is that the maps show all the matter (through its gravitational effects) not just the luminous part that might be seen in a galaxy surveys, so they might provide more direct ways of testing cosmological theories.