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Growing Neutrinos and Quintessence

Growing Neutrinos and Quintessence. Dark Energy dominates the Universe. Energy - density in the Universe = Matter + Dark Energy 25 % + 75 %.

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Growing Neutrinos and Quintessence

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  1. Growing Neutrinos and Quintessence

  2. Dark Energy dominates the Universe Energy - density in the Universe = Matter + Dark Energy 25 % + 75 %

  3. Matter : everything that clumps--------------------Dark Energy density isthe same at every point of space “ homogeneous “Space between clumps is not empty

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

  5. 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 ?

  6. Cosm. Const | Quintessence static | dynamical

  7. 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

  8. 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?

  9. Quintessence Dynamical dark energy , generated by scalarfield (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

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

  11. 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 ! V(φ) =M4 exp( - αφ/M )

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

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

  14. 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

  15. exponential potentialconstant fraction in dark energy can explain order of magnitude of dark energy ! Ωh = 3(4)/α2

  16. realistic quintessence fraction in dark energy has to increase in “recent time” !

  17. Quintessence becomes important “today” No reason why w should be constant in time !

  18. cosmic coincidence

  19. coincidence problem What is responsible for increase of Ωh for z < 6 ? Why now ?

  20. growing neutrino mass triggers transition to almost static dark energy growing neutrino mass

  21. cosmon coupling to neutrinos basic ingredient :

  22. Cosmon coupling to neutrinos • can be large ! • interesting effects for cosmology if neutrino mass is growing • growing neutrinos can stop the evolution of the cosmon • transition from early scaling solution to cosmological constant dominated cosmology Fardon,Nelson,Weiner L.Amendola,M.Baldi,…

  23. growing neutrinos

  24. end of matter domination • growing mass of neutrinos • at some moment energy density of neutrinos becomes more important than energy density of dark matter • end of matter dominated period • similar to transition from radiation domination to matter domination • this transition happens in the recent past • cosmon plays crucial role

  25. cosmological selection • present value of dark energy density set by cosmological event ( neutrinos become non – relativistic ) • not given by ground state properties !

  26. connection between dark energy and neutrino properties present dark energy density given by neutrino mass present equation of state given by neutrino mass !

  27. dark energy fraction determined by neutrino mass constant neutrino - cosmon coupling β variable neutrino - cosmon coupling

  28. varying neutrino – cosmon coupling • specific model • can naturally explain why neutrino – cosmon coupling is much larger than atom – cosmon coupling

  29. neutrino mass seesaw and cascade mechanism triplet expectation value ~ doublet squared omit generation structure

  30. cascade mechanism triplet expectation value ~ M.Magg , … G.Lazarides , Q.Shafi , …

  31. varying neutrino mass ε≈ -0.05 triplet mass depends on cosmon field φ neutrino mass depends on φ

  32. “singular” neutrino mass triplet mass vanishes for φ → φt neutrino mass diverges for φ → φt

  33. strong effective neutrino – cosmon coupling for φ → φt

  34. crossover fromearly scaling solution to effective cosmological constant

  35. early scaling solution ( tracker solution ) neutrino mass unimportant in early cosmology

  36. growing neutrinos change cosmon evolution modification of conservation equation for neutrinos

  37. effective stop of cosmon evolution cosmon evolution almost stops once • neutrinos get non –relativistic • ß gets large This always happens for φ → φt !

  38. effective cosmological triggerfor stop of cosmon evolution :neutrinos get non-relativistic • this has happened recently ! • sets scales for dark energy !

  39. dark energy fraction determined by neutrino mass constant neutrino - cosmon coupling β variable neutrino - cosmon coupling

  40. cosmon evolution

  41. neutrino fraction remains small Ων mν = 0.45 eV z

  42. equation of state present equation of state given by neutrino mass !

  43. oscillating neutrino mass

  44. Hubble parameter as compared to ΛCDM mν=0.45 eV

  45. Hubble parameter ( z < zc ) only small difference from ΛCDM !

  46. Can time evolution of neutrino mass be observed ? • Experimental determination of neutrino mass may turn out higher than upper bound in model for cosmological constant ( KATRIN, neutrino-less double beta decay ) GERDA

  47. neutrino fluctuations neutrino structures become nonlinear at z~1 for supercluster scales stable neutrino-cosmon lumps exist D.Mota , G.Robbers , V.Pettorino , … N.Brouzakis , N.Tetradis ,…

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

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

  50. 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

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