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SUMMARY:The Effect of a Chameleon Scalar Field on the CMB in Galaxy Cluste
 rs - Camilla Schelpe (DAMTP)
DTSTART:20090223T130000Z
DTEND:20090223T140000Z
UID:TALK15646@talks.cam.ac.uk
CONTACT:David Mulryne
DESCRIPTION:Chameleon scalar fields have been proposed as candidates for d
 ark\nenergy. The chameleon property\, whereby the mass of the scalar depen
 ds on\nthe surrounding matter density\, allows the scalar field to have a 
 strong\ncoupling to normal matter and yet still evade fifth force constrai
 nts. A\ndirect coupling between the chameleon scalar field and the electro
 magentic\nfield has been postulated\, which causes mixing between photons 
 and\nchameleons in a magnetic field. We examine the effects of this mixing
  on the\nCMB when it passes through the magnetic field of a galaxy cluster
 . The\nmixing affects both the intensity and polarisation of the incoming\
 nradiation. We predict the modification to the Stokes parameters of the CM
 B\nradiation over a range of typical galaxy clusters\, and compare our\npr
 edictions for the specific case of the Coma cluster to observations of the
 \nSunyaev-Zel'dovich effect.\n
LOCATION:Potter Room\,  CMS\, Pav.B\, First Floor Common Room (B1.19)
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