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Dunkle Energie – Ein kosmisches Raetsel

Quintessence. Dunkle Energie – Ein kosmisches Raetsel. Quintessence. C.Wetterich. A.Hebecker,M.Doran,M.Lilley,J.Schwindt, C.M ü ller,G.Sch ä fer,E.Thommes, R.Caldwell. What is our Universe made of ?. Quintessence !. fire , air, water, soil !. critical density.

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Dunkle Energie – Ein kosmisches Raetsel

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  1. Quintessence Dunkle Energie – Ein kosmisches Raetsel

  2. Quintessence C.Wetterich A.Hebecker,M.Doran,M.Lilley,J.Schwindt, C.Müller,G.Schäfer,E.Thommes, R.Caldwell

  3. What is our Universemade of ?

  4. Quintessence ! fire , air, water, soil !

  5. critical density • ρc =3 H² M² critical energy density of the universe ( M : reduced Planck-mass , H : Hubble parameter ) • Ωb=ρb/ρc fraction in baryons energy density in baryons over critical energy density

  6. Composition of the universe Ωb = 0.045 Ωdm= 0.225 Ωh = 0.73

  7. gravitational lens , HST

  8. spatially flat universe Ωtot = 1 • theory (inflationary universe ) Ωtot =1.0000……….x • observation ( WMAP ) Ωtot =1.02 (0.02)

  9. picture of the big bang

  10. Wilkinson Microwave Anisotropy Probe A partnership between NASA/GSFC and Princeton Science Team: NASA/GSFC Chuck Bennett (PI) Michael Greason Bob Hill Gary Hinshaw Al Kogut Michele Limon Nils Odegard Janet Weiland Ed Wollack Brown Greg Tucker UCLA Ned Wright Princeton Chris Barnes Norm Jarosik Eiichiro Komatsu Michael Nolta Chicago Stephan Meyer UBC Mark Halpern Lyman Page Hiranya Peiris David Spergel Licia Verde

  11. mean values Ωtot =1.02 Ωm =0.27 Ωb =0.045 Ωdm =0.225

  12. Ωtot=1

  13. Dark Energy Ωm + X = 1 Ωm : 30% Ωh : 70% Dark Energy h : homogenous , often ΩΛ instead of Ωh

  14. Dark Energy : homogeneously distributed

  15. Dark Energy : prediction: The expansion of the Universe accelerates today !

  16. Perlmutter 2003

  17. Supernova cosmology Riess et al. 2004

  18. Structure formation : fluctuation spectrum CMB agrees with galaxy distribution Lyman – α forest and gravitational lensing effect ! Waerbeke

  19. consistent cosmological model !

  20. Composition of the Universe Ωb = 0.045 visible clumping Ωdm= 0.225 invisibleclumping Ωh = 0.73 invisiblehomogeneous

  21. What is Dark Energy ? Cosmological Constant or Quintessence ?

  22. Dynamics of Dark Energy

  23. Cosmological Constant • Constant λ compatible with all symmetries • No time variation in contribution to energy density • Why so small ? λ/M4 = 10-120 • Why important just today ?

  24. λ≠ 0 ( ρ + λ)

  25. asymptotic solution for cosmological constant (k=0)

  26. problems with small λ • no symmetry explanation for λ/M4 =10 -120 • quantum fluctuations contribute

  27. Anthropic principle Banks Weinberg Linde

  28. Cosmological Constant • Constant λ compatible with all symmetries • No time variation in contribution to energy density • Why so small ? λ/M4 = 10-120 • Why important just today ?

  29. Cosm. Const. | Quintessence static | dynamical

  30. Energy density ρ ~ ( 2.4×10 -3 eV )- 4 Reduced Planck mass M=2.44×1018GeV Newton’s constant GN=(8πM²) Cosmological mass scales Only ratios of mass scales are observable ! homogeneous dark energy: ρh/M4 = 6.5 10ˉ¹²¹ matter: ρm/M4= 3.5 10ˉ¹²¹

  31. Time evolution tˉ² matter dominated universe tˉ3/2 radiation dominated universe • ρm/M4 ~ aˉ³ ~ • ρr/M4 ~ aˉ4~ t -2radiation dominated universe Huge age small ratio Same explanation for small dark energy?

  32. Quintessence Dynamical dark energy , generated by scalar field (cosmon) C.Wetterich,Nucl.Phys.B302(1988)668, 24.9.87 P.J.E.Peebles,B.Ratra,ApJ.Lett.325(1988)L17, 20.10.87

  33. Cosmon • Scalar field changes its value even in the present cosmological epoch • Potential und kinetic energy of cosmon contribute to the energy density of the Universe • Time - variable dark energy : ρh(t) decreases with time !

  34. Cosmon • Tiny mass • mc ~ H • New long - range interaction

  35. “Fundamental” Interactions Strong, electromagnetic, weak interactions On astronomical length scales: graviton + cosmon gravitation cosmodynamics

  36. Evolution of cosmon field Field equations Potential V(φ) determines details of the model e.g. V(φ) =M4 exp( - φ/M ) for increasing φ the potential decreases towards zero !

  37. Cosmological equations matter ^ ^

  38. Cosmological equations

  39. asymptotic solution for large time M → ^M

  40. exponential potentialconstant fraction in dark energy

  41. General mechanism for cosmic attractor

  42. Cosmic Attractors Solutions independent of initial conditions typically V~t -2 φ ~ ln ( t ) Ωh ~ const. details depend on V(φ) or kinetic term early cosmology

  43. A few references C.Wetterich , Nucl.Phys.B302,668(1988) , received 24.9.1987 P.J.E.Peebles,B.Ratra , Astrophys.J.Lett.325,L17(1988) , received 20.10.1987 B.Ratra,P.J.E.Peebles , Phys.Rev.D37,3406(1988) , received 16.2.1988 J.Frieman,C.T.Hill,A.Stebbins,I.Waga , Phys.Rev.Lett.75,2077(1995) P.Ferreira, M.Joyce , Phys.Rev.Lett.79,4740(1997) C.Wetterich , Astron.Astrophys.301,321(1995) P.Viana, A.Liddle , Phys.Rev.D57,674(1998) E.Copeland,A.Liddle,D.Wands , Phys.Rev.D57,4686(1998) R.Caldwell,R.Dave,P.Steinhardt , Phys.Rev.Lett.80,1582(1998) P.Steinhardt,L.Wang,I.Zlatev , Phys.Rev.Lett.82,896(1999)

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