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SUMMARY:Reconstruction of the Dark Energy Equation of State and the Primor
 dial Power Spectrum P(k) - Jose Vazquez (Cavendish Astrophysics)
DTSTART:20120612T153000Z
DTEND:20120612T163000Z
UID:TALK37892@talks.cam.ac.uk
CONTACT:David Titterington
DESCRIPTION:The major task for present and future dark energy surveys is t
 o determine whether dark energy is evolving in time.  Using the latest cos
 mological datasets (SN\, CMB and LSS)\, we have performed a Bayesian analy
 sis to extract the general form of the dark energy equation-of-state param
 eter\, employing an optimal nodal reconstruction where w(z) is interpolate
 d linearly between a set of nodes with varying w_z-amplitudes and redshift
 s.  Our method has the advantage that the number and location of nodes are
  directly chosen by the Bayesian evidence.  We find our results to be gene
 rally consistent with the cosmological constant scenario\, though with wea
 k evidence for some temporal evolution as well.  Besides the cosmological 
 constant\, the preferred w(z) has w<1 at the present time and a small bump
  located at z\\sim0.6\, whereas at redshifts z>1 the accuracy of current d
 ata is not enough to place effective constraints on different parameterisa
 tions.  We also attempted to fit an optimal degree of structure for the pr
 imordial power spectrum of curvature perturbations using the Bayesian mode
 l selection as our discriminating criterion.  The preferred model is provi
 ded by the Lasenby and Doran model followed by a modified power-law versio
 n.  We found that the power-law parameterisation\, including either cases\
 , spectral index n_s and running of the index n_{run}\, are both significa
 ntly disfavoured.
LOCATION:Martin Ryle Seminar Room\, Kavli Institute
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