The Cosmological Slingshot Scenario

1. A Stringy Proposal for Early Time Cosmology: The Cosmological Slingshot Scenario Germani, NEG, Kehagias, hep-th/0611246 Germani, NEG, Kehagias, arXiv:0706.0023 Germani, Ligouri, arXiv:0706.0025

2. It is nearly homogeneous It is expanding It is nearly isotropic It is accelerating The vacuum energy density is very small The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum What do we know about the universe? Standard cosmology 4d metric WMAP collaboration astro-ph/0603449

3. It is nearly homogeneous It is expanding It is nearly isotropic It is accelerating The vacuum energy density is very small The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum Standard cosmology 4d metric Einstein equations Hubble equation Energy density Curvature term

4. It is nearly homogeneous It is expanding It is nearly isotropic It is accelerating The vacuum energy density is very small The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum Standard cosmology Solution 4d metric Plank a Hubble equation Big Bang  t to tPlank

5. 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 Standard cosmology It is nearly homogeneous  is constant in the observable region of 1028 cm Causally disconnected regions are in equilibrium! It is expanding It is accelerating t to tPlank

6. The vacuum energy density is very small The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum Standard cosmology It is nearly homogeneous It is nearly isotropic 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! It is expanding It is accelerating Belinsky, Khalatnikov, Lifshitz, Adv. Phys. 19, 525 (1970) Collins, Hawking Astr.Jour.180, (1973)

7. The vacuum energy density is very small The perturbations around homogeneity have a flat (slightly red) spectrum Standard cosmology It is nearly homogeneous It is nearly isotropic (10-8 at Nuc.) The space is almost flat It is a growing function Since it is small today, it was even smaller at earlier time! It is expanding It is accelerating

8. The vacuum energy density is very small Standard cosmology It is nearly homogeneous It is nearly isotropic What created perturbations? If they were created by primordial quantum fluctuations, its resulting spectrum for normal matter is not flat The space is almost flat Their existence is necessary for the formation of structure (clusters, galaxies) It is expanding It is accelerating The perturbations around homogeneity have a flat (slightly red) spectrum

9. It is nearly homogeneous It is nearly homogeneous Plank Plank a It is nearly isotropic It is nearly isotropic Big Bang The vacuum energy density is very small  The space is almost flat The space is almost flat t to tPlank The perturbations around homogeneity have a flat (slightly red) spectrum The perturbations around homogeneity have a flat (slightly red) spectrum Guth, PRD23, 347 (1981) Linde, PLB108, 389 (1982) Standard cosmology Inflation Solving to the problems It is expanding It is accelerating tearlier < tNuc

10. It is nearly homogeneous It is nearly homogeneous Plank a  The space is almost flat t to Standard cosmology It is nearly isotropic Bounce The vacuum energy density is very small The space is almost flat Quantum regime It is expanding It is accelerating tearlier< tNuc The perturbations around homogeneity have a flat (slightly red) spectrum

11. It is nearly homogeneous Plank Plank a a It is nearly isotropic The vacuum energy density is very small   The space is almost flat t t to to The perturbations around homogeneity have a flat (slightly red) spectrum Standard cosmology Bounce Inflation Quantum regime Can the bounce be classical? It is expanding It is accelerating tearlier< tNuc

12. Plank a  tearlier t to Kehagias, Kiritsis hep-th/9910174 Mirage cosmology Cosmological evolution Higher dimensional bulk 3-Brane 4d flat slice Warping factor Matter Universe

13. Plank Plank a Big Bang  t to tPlank Mirage cosmology Increasing warping Monotonousmotion Expanding Universe tearlier How can we obtain a bounce? A minimum in the warping factor Solve Einstein equations A turning point in the motion Solve equations of motion

14. Plank a  tearlier t to Germani, NEG, Kehagias hep-th/0611246 Slingshot cosmology x|| Cosmological expansion 10d bulk IIB SUGRA solution 4d flat slice BPS D3-Brane Warping factor Xaü

15. Plank a  x|| tearlier t to Slingshot cosmology RR field Dilaton field Induced metric Xaü Bounce Burgess, Quevedo, Rabadan, Tasinato, Zavala, hep-th/0310122 Turning point Xaü

16. Plank a  tearlier t to Slingshot cosmology Transverse metric 6d flat euclidean metric Free particle AdS5xS5 space Bounce Xaü Turning point Warping factor Non-vanishing angular momentum l Non-vanishing impact parameter Xaü Burgess, Martineau , Quevedo, Rabadan, hep-th/0303170 Burgess, NEG, F. Quevedo, Rabadan, hep-th/0310010 Heavy source Stack of branes

17. Plank a  tearlier t to Slingshot cosmology 6d flat Euclidean metric There is no space curvature Free particle AdS5xS5 space Xaü Non-vanishing angular momentum l Xaü Heavy source Stack of branes

18. Plank a  tearlier t to Slingshot cosmology There is no space curvature Flatness problem is solved Can we solve the flatness problem? Constraint in parameter space

19. Plank a  tearlier t to Slingshot cosmology All the higher orders in r´ What about isotropy? Isotropy problem is solved Dominates at early time, avoiding chaotic behaviour

20. Plank a  tearlier t to Slingshot cosmology And about perturbations?

21. Plank a  tearlier t to Germani, NEG, Kehagias arXiv:0706.0023 Slingshot cosmology Boehm, Steer, hep-th/0206147 Induced scalar Bardeen potential And about perturbations? Scalar field Harmonic oscillator Growing modes Frozen modes Oscilating modes Decaying modes Frozen modes survive up to late times Decaying modes do not survive

22. Plank a  tearlier t to = < > h* Slingshot cosmology Frozen modes Power spectrum Created by quantum perturbations

23. Plank a  tearlier t to h* Slingshot cosmology l > lcClassical mode l < lcQuantum mode r*= kL/ lc Creation of the mode l = lcCreation of the mode l=k /a= kL / r We get a flat spectrum Power spectrum Hollands, Wald gr-qc/0205058

24. Plank a  tearlier t to Slingshot cosmology Late time cosmology Gravity is ten dimensional Compactification AdS throat in a CY space Formation of structure Kepler laws Mirage domination in the throat Local gravity domination in the top Real life! The transition is out of our control Local 4d gravity dominated era Mirage dominated era backreaction Top of the CY AdS throat

25. Slingshot cosmology It is nearly homogeneous Open Points Nice Results It is nearly isotropic The price we paid is an unknown transition region between local and mirage gravity (reheating) Klevanov-Strassler geometry gives a slightly red spectral index, in agreement with WMAP The vacuum energy density is very small The space is almost flat Problems with Hollands and Wald proposal are avoided in the Slingshot scenario There is no effective 4D theory Back-reaction effects should be studied An effective 4D action can be found It is expanding It is accelerating The perturbations around homogeneity have a flat spectrum

26. Thanks!