1 / 87

Dunkle Energie – Ein kosmisches Raetsel

Quintessence. Dunkle Energie – Ein kosmisches Raetsel. Dark energy – a cosmic mystery. 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.

gezana
Télécharger la présentation

Dunkle Energie – Ein kosmisches Raetsel

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Quintessence Dunkle Energie – Ein kosmisches Raetsel

  2. Dark energy –a cosmic mystery 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. Ωm≈0.3 gravitational lens , HST

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

  9. picture of the big bang

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

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

  12. Dark Energy : homogeneously distributed

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

  14. Cosmological Constant- Einstein - • 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 ?

  15. Cosm. Const. | Quintessence static | dynamical

  16. 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

  17. 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?

  18. 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

  19. Prediction : homogeneous dark energyinfluences recent cosmology- of same order as dark matter - Original models do not fit the present observations …. modifications

  20. 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 !

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

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

  23. 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 !

  24. 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

  25. Quintessence becomes important “today”

  26. Equation of state p=T-V pressure kinetic energy ρ=T+V energy density Equation of state Depends on specific evolution of the scalar field

  27. Negative pressure • w < 0 Ωh increases (with decreasing z ) • w < -1/3 expansion of the Universe is accelerating • w = -1 cosmological constant late universe with small radiation component :

  28. small early and large presentdark energy fraction in dark energy has substantially increased since end of structure formation expansion of universe accelerates in present epoch

  29. How can quintessence be distinguished from a cosmological constant ?

  30. Time dependence of dark energy cosmological constant : Ωh ~ t² ~ (1+z)-3 M.Doran,…

  31. Measure this curve !

  32. Early dark energy A few percent in the early Universe Not possible for a cosmological constant

  33. Quintessence and time variation of fundamental constants Generic prediction Strength unknown Strong, electromagnetic, weak interactions C.Wetterich , Nucl.Phys.B302,645(1988) gravitation cosmodynamics

  34. Are fundamental “constants”time dependent ? Fine structure constant α (electric charge) Ratio nucleon mass to Planck mass

  35. Quintessence and time dependence of “fundamental constants” • Fine structure constant depends on value of cosmon field : α(φ) (similar in standard model: couplings depend on value of Higgs scalar field) • Time evolution of φ Time evolution of α Jordan,…

  36. Field dependent gauge coupling( gauge invariance maintained ) for GUT : C.Hill ; Q.Shafi , CW

  37. GUT : running of electromagneticand strong gauge coupling related strong effect from variation of nucleon mass for time dependent couplings ! X.Calmet , H.Fritzsch

  38. Where to look for time variation of fundamental couplings ? • Nucleosynthesis • Molecular absorption lines in the light of distant Quasars • Oklo natural reactor • Atomic clocks • CMB

  39. Abundancies of primordial light elements from nucleosynthesis A.Coc

  40. if present 2-sigma deviation of He –abundance from CMB/nucleosynthesis prediction would be confirmed : Δα/α ( z=1010 ) = -1.0 10-3 GUT 1 Δα/α ( z=1010 ) = -2.7 10-4 GUT 2 C.Mueller,G.Schaefer,…

  41. Variation of fine structure constant as function of redshift Webb et al Srianand et al

  42. Variation of fine structure constant Three independent data sets from Keck/HIRES Δα/α = - 0.54 (12) 10-5 Murphy,Webb,Flammbaum, june 2003 VLT Δα/α = - 0.06 (6) 10-5 Srianand,Chand,Petitjean,Aracil, feb.2004 z ≈ 2

  43. Crossover quintessence andtime variation of fundamental “constants” Upper bounds for relative variation of the fine structure constant • Oklo natural reactor Δα/α < 10 -7 z=0.13 • Meteorites ( Re-decay ) Δα/α < 3 10 -7 z=0.45 • Crossover Quintessence compatible with QSO and upper bounds !

  44. Time evolution of fundamental couplings traces time evolution of quintessence • todaywh close to -1 : • Small kinetic energy • Slow change of φ • Slow change of α • Very small Δα/αfor low z !

  45. Variation of fine structure constant as function of redshift Webb et al

  46. Atomic clocks and OKLO assumes that both effects are dominated by change of fine structure constant

  47. Time variation of coupling constants must be tiny – would be of very high significance ! Possible signal for Quintessence

  48. Πανταρει everything flows

  49. Cosmodynamics Cosmon mediates new long-range interaction Range : size of the Universe – horizon Strength : weaker than gravity photon electrodynamics graviton gravity cosmon cosmodynamics Small correction to Newton’s law

  50. Violation of equivalence principle Different couplings of cosmon to proton and neutron Differential acceleration Violation of equivalence principle p,n earth cosmon p,n

More Related