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Probing Dark Energy with Cosmological Observations

Probing Dark Energy with Cosmological Observations. Fan, Zuhui ( 范祖辉 ) Dept. of Astronomy Peking University. Outline Introduction Cosmological Probes Current Status Future. Introduction The development of cosmology is

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Probing Dark Energy with Cosmological Observations

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  1. Probing Dark Energy with Cosmological Observations Fan, Zuhui (范祖辉) Dept. of Astronomy Peking University

  2. Outline • Introduction • Cosmological Probes • Current Status • Future

  3. Introduction The development of cosmology is driven by observations

  4. The universe is expanding ( ) – Big Bang Hubble

  5. The expansion is accelerating ( ) (1998, 1999)

  6. Standard cosmological scenario: Einstein’s equations govern the evolution of the universe R: scale factor of the universe

  7. Normal matter: The accelerating universe calls for the existence of dark energy with negative pressure

  8. Understanding the nature of dark energy Theoretical physics: dark energy models Cosmology: extract constraints on dark energy from different observations w=-1? w=constant? w(z) ?

  9. Cosmological probes on dark energy • Global properties of the universe Geometry and expansion history of the universe • Dynamical evolution of the large-scale structure of the universe

  10. Expansion of the universe: SNe Ia: standard candle  luminosity distance Clusters of galaxies: SZ+X-ray  angular diameter distance

  11. Geometry of the universe: CMB: angular positions of the sound peaks sensitive to the total matter content

  12. Dynamical evolution of the universe Large-scale structure of the universe galaxy redshift surveys power spectrum correlation function

  13. detection of acoustic peak from the SDSS LRG sample Eisenstein et al. astro-ph/0501171

  14. Dark energy dependence growth factor of density perturbations Cosmological distortion: AP test

  15. The formation and evolution of clusters of galaxies abundance evolution: density growth volume element

  16. gas fraction in clusters of galaxies assume the gas fraction fgas(z) invariant  constraints on cosmology (dA(z) – z relation)

  17. Gravitational lensing strong lensing weak lensing dynamical evolution of density perturbations angular diameter distances to the source, to the lens, and from lens to the source

  18. Current status SNe Ia (Riess et al. 2004 astro-ph/0402512 ApJ, 607, 665)

  19. Dark energy constraints equation of state constant w

  20. w(z)

  21. Lyα+galaxy bias+SNe+CMB (Seljak et al. 2004, astro-ph/0407372, PRD, 71, 103515 (2005)) constant w

  22. cluster gas fraction +CMB+SN (Rapetti et al. MNRAS, 360, 555 (2005))

  23. equation of state

  24. weak lensing (M. Jarvis et al. astro-ph/0502243) CTIO lensing survey: 75 deg2, 19<R<23, 2*106 gal

  25. dark energy constraint constant w

  26. w(a) the second peak corresponds to w(a=0)~1 not physically relevant

  27. As of today: w=-1 (cosmological constant) is consistent with all the observational data available to us Slightly favor w<-1

  28. Future SNe Ia SNAP Supernova/Acceleration Probe

  29. Dark energy constraints

  30. SNAP: weak lensing survey Deep survey: 15 deg2, 250/arcmin2 Wide survey: 300-1000 deg2 100/arcmin2 Panoramic survey: 10000 deg2 40-50/acrmin2

  31. Equation of state

  32. CMB: Planck standard ruler: sound horizon  baryon wiggles in matter power spectrum determination of other parameters Ωtotal,σ8, Ωm, Ωb, … ISW Large-scale structure: LAMOST

  33. LAMOST galaxy redshift survey (Sun, Su and Fan 2005) three redshift bins centered at 0.3, 0.4, and 0.5 distant observer approximation

  34. With bins of higher redshifts, the constraints can be improved

  35. Without distant-observer approximation z=0.2-0.4

  36. a

  37. Parameterization Priors systematic errors

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