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Niels Bohr Summer Institute 27/8-07

Niels Bohr Summer Institute 27/8-07. Beyond Lambda. Edvard Mörtsell Eric Linder: Interpreting dark energy Steen Hannestad: Theoretical problems and perspectives in dark energy Tamara Davis: Where Beyond Lambda meets supernovae. Expansion history of our universe. Cosmological distances

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Niels Bohr Summer Institute 27/8-07

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  1. Niels Bohr Summer Institute 27/8-07 Beyond Lambda Edvard Mörtsell Eric Linder: Interpreting dark energy Steen Hannestad: Theoretical problems and perspectives in dark energy Tamara Davis: Where Beyond Lambda meets supernovae

  2. Expansion history of our universe • Cosmological distances • Type Ia supernovae (z = 0 – 1.7) • CMB (scale of acoustic oscillations at z = 1100) • Baryon Acoustic Oscillations (scale at z = 0.35) • Growth of structure • Galaxy surveys (z = 0 – 1) • Cluster abundances (z = 0 – 1) • Weak lensing (z = 0 – 2) Late ISW, age of universe… Constraints on non-standard dark energy

  3. 2 2 G ¤ _ ¡ ¢ 8 a ¼ · c ¡ + ² = 2 2 2 3 R 3 a c a The cosmological constant (Lambda, CC) with w = -1 provides a good fit to all data 0 An accelerating expansion • Dominant dark energy component with negative equation of state, w • Modified (large scale) gravity • Inhomogeneous solutions of field equations Constraints on non-standard dark energy

  4. Supernova data 60 ESSENCE 57 SNLS 45 nearby 30 HST MCLS2k2 fitter Additional data WMAP 3-yr CMB (scale of acoustic oscillations at z = 1100) SDSS BAO (scale of acoustic oscillations at z = 0.35) Cosmological results from distance probes Davis, EM, Sollerman et al (2007) Supernova data available at www.dark-cosmology.dk/archive/SN Constraints on non-standard dark energy

  5. Constrained models give artificial constraints on DE properties ( ) ( ) 1 t t + ¡ w w a w w c o n w s a n a = = = 0 0 a Results CC model 95 % confidence levels Constraints on non-standard dark energy

  6. Model independent fits Sullivan, Cooray & Holz (2007) Make a piecewise parametrization of w, i.e. let wi be the (constant) value of w(z) in a redshift bin i Decorrelate wi with a linear transformation wi=> Wi Constraints on non-standard dark energy

  7. Summary • No strong indications for temporal or spatial variation of dark energy properties • Complex models are not supported by data but still room for sizeable deviations from CC • Claims of deviations from CC will be subject to intense scrutiny • Independent measurements needed Constraints on non-standard dark energy

  8. New data (and analysis methods) • 21 cm observations (z = 10 - 100) • Strong lensing • GRB distances • Cluster x-rays • SZ effect • dz/dt from galaxies • Direct measurements of dz/dt • Laboratory tests of modified gravity • Gravitational wave sirens Constraints on non-standard dark energy

  9. Topics for discussion • Interplay between theory and observations. • What should be our ”working model”? • How should we fit dark energy? • What constitutes a (non-)detection of dynamical DE? • How do we judge the worth of a data set? (FoM)? • DE vs modified gravity models • What redshifts should we focus on? • How do we probe spatial variations? • … Constraints on non-standard dark energy

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