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SUMMARY:What do galaxy surveys really measure? - Camille Bonvin (Cambridge
 )
DTSTART:20120302T130000Z
DTEND:20120302T140000Z
UID:TALK36570@talks.cam.ac.uk
CONTACT:Ian A. Morrison
DESCRIPTION:Galaxy redshift surveys measure the distribution of galaxies a
 s\na function of redshift. This observation is then used to infer the\nund
 erlying matter power spectrum and learn about structure formation and\ncos
 mological\nparameters. The link between observation and matter density is 
 however not\nas simple as it is usually assumed. It is known since a long 
 time\, that\ngalaxy number density measurements are affected by redshift-s
 pace\ndistortion. In this talk I will show that in addition to this well-k
 nown\ncorrection\, various relativistic effects enter in the relation betw
 een the\nobserved galaxy number density and the underlying physical quanti
 ties. I\nwill show how to express the observable in terms of gauge invaria
 nt\nvariables and I will discuss the various corrections to the standard\n
 result.
LOCATION:Pavilion B Potter Room (B1.19)
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