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L. Perivolaropoulos http://leandros.physics.uoi.gr Department of Physics University of Ioannina

This study by L. Perivolaropoulos explores recent geometric probe data, such as SnIa, CMB, BAO, and their impact on the expansion rate of the universe. It addresses conflicts between ΛCDM predictions and observations, offering insights into Dark Energy clustering. The potential resolution through Scalar-Tensor cosmologies is discussed, along with analyses of Figures of Merit and consistency with ΛCDM and Standard Rulers. The study raises puzzles for ΛCDM related to large-scale velocity flows and galaxy cluster halo profiles, emphasizing the need for clustered dark energy models. The interplay between expansion rate and dark energy clustering is explored, providing a new perspective on cosmological constraints.

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L. Perivolaropoulos http://leandros.physics.uoi.gr Department of Physics University of Ioannina

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  1. Open page Accelerating Universe: Geometric Observational Constraints and Growth of Perturbations L. Perivolaropouloshttp://leandros.physics.uoi.gr Department of Physics University of Ioannina

  2. Main Points Recent Geometric Probe Data (SnIa, CMB, BAO) Expansion Rate of the Universe is very similarto the rate predicted by ΛCDM There are some puzzling conflicts between ΛCDM predictions and LSS cosmological observations Large Scale Velocity Flows (3σ) Galaxy and Cluster Halo Profiles (2σ-3σ) There is a potential resolution of these conflicts if Dark Energy had clustering properties. Q: Is there a concrete physical model where dark energy can have significant clustering properties on small scales? Yes. This naturally occurs in Scalar-Tensor cosmologies due to the direct coupling of the scalar field perturbations to matter induced curvature perturbations

  3. Geometric Probes: Recent SnIa Datasets Q1: What is the Figure of Merit of each dataset? Q2: What is the consistency of each dataset with ΛCDM? Q3: What is the consistency of each dataset with Standard Rulers? J. C. Bueno Sanchez, S. Nesseris, LP, JCAP 0911:029,2009, 0908.2636

  4. Figures of Merit The Figure of Merit:Inverse area of the 2σ CPL parameter contour.A measure of the effectiveness of the dataset in constraining the given parameters. GOLD06 SNLS ESSENCE UNION CONSTITUTION WMAP5+SDSS5 WMAP5+SDSS7

  5. Figures of Merit The Figure of Merit:Inverse area of the 2σ CPL parameter contour.A measure of the effectiveness of the dataset in constraining the given parameters. SDSS5 Percival et. al. SDSS7 Percival et. al.

  6. Consistency with ΛCDM Trajectories of Best Fit Parameter Point ESSENCE+SNLS+HST data Ω0m=0.24 SNLS 1yr data The trajectories of SNLS and Constitution are clearly closer to ΛCDM for most values of Ω0m Gold06 is the furthest from ΛCDM for most values of Ω0m Q: What about the σ-distance (dσ) from ΛCDM?

  7. The σ-distance to ΛCDM ESSENCE+SNLS+HST data Trajectories of Best Fit Parameter Point Consistency with ΛCDM Ranking:

  8. The σ-distance to Standard Rulers ESSENCE+SNLS+HST Trajectories of Best Fit Parameter Point Consistency with Standard Rulers Ranking:

  9. Puzzles for ΛCDM From LP, 0811.4684 Large Scale Velocity Flows - Predicted: On scale larger than 50 h-1Mpc Dipole Flows of 110km/sec or less. - Observed: Dipole Flows of more than 400km/sec on scales 50 h-1Mpc or larger. - Probability of Consistency:1% R. Watkins et. al. , 0809.4041 Cluster and Galaxy Halo Profiles: - Predicted: Shallow, low-concentration mass profiles - Observed: Highly concentrated, dense halos - Probability of Consistency:3-5% Broadhurst et. al. ,ApJ 685, L5, 2008, 0805.2617, S. Basilakos, J.C. Bueno Sanchez, LP., 0908.1333, PRD, 80, 043530, 2009.

  10. Cluster Halo Profiles Navarro, Frenk, White, Ap.J., 463, 563, 1996 NFW profile: From S. Basilakos, J.C. Bueno-Sanchez and LP, PRD, 80, 043530, 2009, 0908.1333. ΛCDM prediction: The predicted concentration parameter cvir is significantly smaller than the observed. Data from:

  11. Cluster Halo Profiles Navarro, Frenk, White, Ap.J., 463, 563, 1996 From S. Basilakos, J.C. Bueno-Sanchez and LP, PRD, 80, 043530, 2009, 0908.1333. NFW profile: clustered dark energy Clustered Dark Energy can produce more concentrated halo profiles Data from:

  12. Producing Dark energy Perturbations Q: Is there a model with a similar expansion rate as ΛCDM but with significant clustering of dark energy? A: Yes. This naturally occurs in Scalar-Tensor cosmologies due to the direct coupling of the scalar field perturbations to matter induced curvature perturbations

  13. Scalar-Tensor Theories Rescale Φ Units: General Relativity: Generalized Einstein-Field Equations:

  14. Background Cosmological Evolution Flat FRW metric: Generalized Friedman equations:

  15. Advantages and Constraints • Advantages: • Natural generalizations of GR (superstring dilaton, Kaluza-Klein theories) • General theories (f(R) and Brans-Dicke theories consist a special case of ST) • Potential for Resolution of Coincidence Problem • Natural Super-acceleration (weff<-1) • Amplified Dark Energy Perturbations Constraints: Solar System Cosmology

  16. Background Evolution J. C. BuenoSanchez., LP in preparation

  17. Minimally Coupled Quintessence Thawing Minimally Coupled Quintessence

  18. Non-minimal Coupling Oscillations (due to coupling to ρm ) and non-trivial evolution

  19. Effective Equation of State Effective Equation of State: Scalar-Tensor (λf=5) weff Minimal Coupling (λf=0) z

  20. Perturbations: Analytical Approximations Perturbed FRW metric (Newtonian gauge): Generalized Einstein-Field Equations:

  21. Analytical Approximations: Sub-Hubble ST scales No suppression on small scales!

  22. Analytical Approximations: Sub-Hubble GR scales Sub-Hubble GR scales Suppressed fluctuations on small scales! (as in minimally coupled quintessence)

  23. Numerical Solutions Scalar Field Perturbations Minimal Coupling (F=1) Non-Minimal Coupling (F=1-λf2Φ2) Scale = 30 h-1Mpc

  24. Numerical Solutions Matter Density Perturbations Minimal Coupling (F=1) Non-Minimal Coupling (F=1-λf2Φ2)

  25. Numerical Solutions Scalar Field Density Perturbations Minimal Coupling (F=1) Non-Minimal Coupling (F=1-λf2Φ2)

  26. Numerical Solutions Scale Dependence of Dark Energy/Dark Matter Perturbations Minimal Coupling (F=1) Non-Minimal Coupling (F=1-λfΦ2) Dramatic Difference on sub-Hubble scales!

  27. Numerical Solutions Scale Dependence of Dark Energy Perturbations Minimal Coupling (F=1) Non-Minimal Coupling (F=1-λfΦ2) Dramatic Difference on sub-Hubble scales!

  28. SUMMARY Recent Geometric Probe Data (SnIa, CMB, BAO) are increasingly consistent with ΛCDM and with each other. The Constitution SnIa dataset is of the highest quality and is also the most consistent with ΛCDM and with Standard Rulers. Observed Cluster Halo Profiles are significantly more concentrated than predicted by ΛCDM. This may be interpreted as a trace of an additional clustering energy component in the halo. Scalar Tensor cosmologies are generic extensions of GR. They naturally allow for crossing of the w=-1 line and amplified dark energy perturbations on sub-Hubble scale by a factor of more than 104compared to quintessence. This may help in the resolution of the cluster profile puzzle.

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