Slingshot Cosmology - Porto

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Slingshot Cosmology - Porto

  1. 1. The Cosmological Slingshot Scenario A New Proposal for Early Time Cosmology Germani, NEG, Kehagias, hep-th/0611246 Germani, NEG, Kehagias, arXiv:0706.0023 Germani, Ligouri, arXiv:0706.0025
  2. 2. Standard cosmology Space curvature  + 1, 0 4d metric Cosmic time Scale factor Space Coordinates (polar) WMAP collaboration astro-ph/0603449 It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum What do we know about the universe?
  3. 3. Standard cosmology 4d metric Einstein equations Hubble equation Energy density Curvature term Equation of state Energy Conditions It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum
  4. 4. Standard cosmology Equation of state 4d metric Hubble equation t o a  t  Plank t Plank Big Bang Solution It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum
  5. 5. Standard cosmology It is nearly homogeneous It is expanding It is accelerating t o t t Plank   is constant in the observable region of 10 28 cm Causally disconnected regions are in equilibrium! It is nearly isotropic The vacuum energy density is very small The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum
  6. 6. Standard cosmology It is nearly homogeneous It is nearly isotropic It is expanding It is accelerating Isotropic solutions form a subset of measure zero on the set of all Bianchi solutions Perturbations around isotropy dominate at early time, like a -6 , giving rise to chaotic behavior! Belinsky, Khalatnikov, Lifshitz, Adv. Phys. 19, 525 (1970) Collins, Hawking Astr.Jour.180, (1973) The vacuum energy density is very small The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum
  7. 7. Standard cosmology It is nearly homogeneous It is nearly isotropic It is expanding It is accelerating The space is almost flat It is a growing function Since it is small today, it was even smaller at earlier time! (10 -8 at Nuc.) The vacuum energy density is very small The perturbations around homogeneity have a flat (slightly red) spectrum
  8. 8. Standard cosmology It is nearly homogeneous It is nearly isotropic It is expanding It is accelerating The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum What created perturbations? If they were created by primordial quantum fluctuations, its resulting spectrum for 2 - n < 6 is not flat Their existence is necessary for the formation of structure (clusters, galaxies) The vacuum energy density is very small
  9. 9. Standard cosmology Solving to the problems Inflation It is expanding It is accelerating t earlier < t Nuc Guth, PRD 23 , 347 (1981) Linde, PLB 108 , 389 (1982) The perturbations around homogeneity have a flat (slightly red) spectrum The perturbations around homogeneity have a flat (slightly red) spectrum  Plank t Plank Big Bang  Plank It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small The space is almost flat  t o a t It is nearly homogeneous The space is almost flat It is nearly isotropic
  10. 10. Standard cosmology The perturbations around homogeneity have a flat (slightly red) spectrum It is nearly isotropic Bounce The vacuum energy density is very small It is expanding It is accelerating The space is almost flat t earlier < t Nuc Quantum regime Lasts enough? The space is almost flat  Plank It is nearly homogeneous  t o a t It is nearly homogeneous
  11. 11. Standard cosmology Bounce Inflation It is expanding It is accelerating t earlier < t Nuc Quantum regime Can the bounce be classical?  Plank  t o a t  Plank  t o a t It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum
  12. 12. Mirage cosmology Higher dimensional bulk 4d flat slice 3-Brane Warping factor Matter Universe Cosmological evolution Kehagias, Kiritsis hep-th/9910174  Plank  t o a t t earlier
  13. 13. Mirage cosmology t earlier Increasing warping Monotonousmotion Expanding Universe How can we obtain a bounce? A minimum in the warping factor A turning point in the motion Solve Einstein equations Solve equations of motion  Plank  Plank t Plank Big Bang  t o a t
  14. 14. Slingshot cosmology 10d bulk IIB SUGRA solution 4d flat slice BPS Warping factor D3-Brane Cosmological expansion X a T x  || Germani, NEG, Kehagias hep-th/0611246  Plank  t o a t t earlier
  15. 15. Slingshot cosmology X a T X a T Dilaton field Induced metric RR field Turning point Bounce Burgess, Quevedo, Rabadan, Tasinato, Zavala, hep-th/0310122 x  ||  Plank  t o a t t earlier
  16. 16. Slingshot cosmology 6d flat euclidean metric Warping factor X a T X a T Transverse metric AdS 5 x S 5 space Free particle Turning point Bounce Non-vanishing impact parameter Non-vanishing angular momentum l Heavy source Stack of branes Burgess, Martineau , Quevedo, Rabadan, hep-th/0303170 Burgess, NEG, F. Quevedo, Rabadan, hep-th/0310010  Plank  t o a t t earlier
  17. 17. Slingshot cosmology Non-vanishing angular momentum l 6d flat Euclidean metric X a T X a T AdS 5 x S 5 space Free particle Heavy source Stack of branes There is no space curvature  Plank  t o a t t earlier
  18. 18. Slingshot cosmology Can we solve the flatness problem? Flatness problem is solved There is no space curvature Constraint in parameter space  Plank  t o a t t earlier
  19. 19. Slingshot cosmology What about isotropy? Dominates at early time, avoiding chaotic behaviour All the higher orders in r´ Isotropy problem is solved  Plank  t o a t t earlier
  20. 20. Slingshot cosmology And about perturbations?  Plank  t o a t t earlier
  21. 21. Slingshot cosmology Induced scalar Bardeen potential And about perturbations? Scalar field Harmonic oscillator Growing modes Oscilating modes Frozen modes Decaying modes Frozen modes survive up to late times Decaying modes do not survive Boehm, Steer, hep-th/0206147 Germani, NEG, Kehagias arXiv:0706.0023    Plank  t o a t t earlier
  22. 22. Slingshot cosmology Frozen modes Power spectrum Created by quantum perturbations  Plank  t o a t t earlier = < >  *
  23. 23. Slingshot cosmology  = l c Creation of the mode r   = kL  / l c Creation of the mode Power spectrum  > l c Classical mode  < l c Quantum mode Hollands, Wald gr-qc/0205058  = k  a  = kL / r We get a flat spectrum  Plank  t o a t t earlier  *
  24. 24. Slingshot cosmology Gravity is ten dimensional Late time cosmology Formation of structure Kepler laws Real life! Compactification AdS throat in a CY space AdS throat Top of the CY Mirage dominated era Local 4d gravity dominated era backreaction Mirage domination in the throat Local gravity domination in the top The transition is out of our control  Plank  t o a t t earlier
  25. 25. Slingshot cosmology Open Points The price we paid is an unknown transition region between local and mirage gravity (reheating) It is nearly isotropic The perturbations around homogeneity have a flat spectrum The space is almost flat It is nearly homogeneous The vacuum energy density is very small It is expanding It is accelerating Nice Results Klevanov-Strassler geometry gives a slightly red spectral index, in agreement with WMAP Problems with Hollands and Wald proposal are avoided in the Slingshot scenario Einstein frame is also compatible with observations There is no effective 4D theory Back-reaction effects should be studied
  26. 26. Thanks!

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