1 / 41

Luca Amendola INAF/Osservatorio Astronomico di Roma

Luca Amendola INAF/Osservatorio Astronomico di Roma. The dark side of gravity. Why DE/MG is interesting. g. How to observe it. Observations are converging…. …to an un expected universe. Classifying the unknown. Standard cosmology: GR gravitational equations + FRW metric.

talor
Download Presentation

Luca Amendola INAF/Osservatorio Astronomico di Roma

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. Luca Amendola INAF/Osservatorio Astronomico di Roma The dark side of gravity Munich 2008

  2. Why DE/MG is interesting g How to observe it Munich 2008

  3. Munich 2008 Observationsareconverging… …to anunexpected universe

  4. Munich 2008 Classifying the unknown • Standard cosmology: • GR gravitational equations + FRW metric a) change the equations i.e. add new matter field (DE) or modify gravity (MG) b) change the metric i.e. inhomogeneous non-linear effects, void models, etc

  5. Modified gravity Which are the effects of modified gravity at background linear level ? non-linear { } Munich 2008

  6. Cosmology and modified gravity very limited time/space/energy scales;only baryons } in laboratoryin the solar systemat astrophysical scalesat cosmological scales complicated by non-linear/non-gravitational effects unlimited scales; mostly linear processes;baryons, dark matter, dark energy ! Munich 2008

  7. How to hide modified gravity (in the solar system) L.A., C. Charmousis, S. Davis, PRD 2008, arXiv 0801.4339 Generalized Brans-Dicke- Gauss-Bonnet Lagrangian Solution in static spherical symmetry in a linearized PPN metric with Conclusion: there are solutions which look “Einsteinian” but are not… Munich 2008

  8. Simplest MG (I): DGP (Dvali, Gabadadze, Porrati 2000) L = crossover scale: • 5D gravity dominates at low energy/late times/large scales • 4D gravity recovered at high energy/early times/small scales 5D Minkowski bulk: infinite volume extra dimension brane gravity leakage Munich 2008

  9. Simplest MG (II): f(R) The simplest MG in 4D: f(R) eg higher order corrections • f(R) models are simple and self-contained (no need of potentials) • easy to produce acceleration (first inflationary model) • high-energy corrections to gravity likely to introduce higher-order terms • particular case of scalar-tensor and extra-dimensional theory Munich 2008

  10. Munich 2008 Is this already ruled out by local gravity? is a scalar-tensor theory with Brans-Dicke parameter ω=0 or a coupled dark energy model with coupling β=1/2 α λ Adelberger et al. 2005

  11. Munich 2008 The fourfold way out of local gravity { depend on time depend on space depend on local density depend on species

  12. Munich 2008 Sound horizon in R+R - n model Turner, Carroll, Capozziello etc. 2003 in the Matter Era ! L.A., D. Polarski, S. Tsujikawa, PRL 98, 131302, astro-ph/0603173

  13. Munich 2008 A recipe to modify gravity Can we find f(R) models that work?

  14. Munich 2008 MG in the background (JF) An autonomous dynamical system characteristic function

  15. Munich 2008 MG in the background Ωγ ΩP ΩK

  16. Munich 2008 Classification of f(R) solutions For all f(R) theories: deSitter acceleration, w = -1 General acceleration, any w wrongmatter era (t1/2) goodmatter era (t2/3) for m≥0

  17. Munich 2008 The power of the m(r) method REJECTED REJECTED REJECTED REJECTED REJECTED

  18. Munich 2008 The triangle of viable trajectories cosmologically viable trajectories Notice that in the triangle m>0 L.A., D. Polarski, S. Tsujikawa 2007 PRD astro-ph/0612180

  19. Munich 2008 Local Gravity Constraints are very tight Depending on the local field configuration depending on the experiment: laboratory, solar system, galaxy see eg. Nojiri & Odintsov 2003; Brookfield et al. 2006 Navarro & Van Acoyelen 2006; Faraoni 2006; Bean et al. 2006; Chiba et al. 2006; Hu, Sawicky 2007; Mota et al. 2006;....

  20. Munich 2008 c LGC+Cosmology Take for instance the ΛCDM clone Applying the criteria of LGC and background cosmology i.e. ΛCDM to an incredible precision

  21. What background hidesperturbations reveal The background expansion only probes H(z)The (linear) perturbations probe first-order quantities Full metric reconstruction at first order requires 3 functions Munich 2008

  22. Munich 2008 Two free functions At the linear perturbation level and sub-horizon scales, a modified gravity model will • modify Poisson’s equation • induce an anisotropic stress (most of what follows in collaboration withM. Kunz, D. Sapone)

  23. Munich 2008 MG at the linear level • standard gravity Boisseau et al. 2000 Acquaviva et al. 2004 Schimd et al. 2004 L.A., Kunz &Sapone 2007 • scalar-tensor models • f(R) Bean et al. 2006 Hu et al. 2006 Tsujikawa 2007 • DGP Lue et al. 2004; Koyama et al. 2006 • coupled Gauss-Bonnet see L. A., C. Charmousis, S. Davis 2006

  24. Reconstruction of the metric Correlation of galaxy positions: galaxy clustering Correlation of galaxy ellipticities: galaxy weak lensing Munich 2008

  25. Peculiar velocities Correlation of galaxy velocities: galaxy peculiar field redshift distortion parameter =0.70±0.2 Guzzo et al. 2008 Munich 2008

  26. The Euclid theorem Observables: Conservation equations: 5 unknown variables: We can measure 3 combinations and we have 2 theoretical relations… Theorem: lensing+galaxy clustering allows to measure all (total matter) perturbation variables at first order without assuming any particular gravity theory Munich 2008

  27. The Euclid theorem Observables: Conservation equations: 5 unknown variables: We can measure 3 combinations and we have 2 theoretical relations… Theorem: lensing+galaxy clustering allows to measure all (total matter) perturbation variables at first order without assuming any particular gravity theory Munich 2008

  28. The Euclid theorem From these we can estimate deviations from Einstein’s gravity: Munich 2008

  29. Munich 2008 Euclid A geometrical probe of the universe proposed for Cosmic Vision All-sky optical imaging for gravitational lensing All-sky near-IR spectra to H=22 for BAO = +

  30. Munich 2008 Weak lensing Euclid forecast Present constraints DGP LCDM Weak lensing tomography over half sky L.A., M. Kunz, D. Sapone arXiv:0704.2421 DiPorto & L.A. 2007

  31. Munich 2008 Power spectrum Galaxy clustering at 0<z<2 over half sky ....if you know the bias to 1%

  32. Munich 2008 Non-linearity in BAO Matarrese & Pietroni 2007

  33. Munich 2008 Poster advertisement Cosmic parallax Garcia-Bellido & Haugbolle 2008 See poster by Miguel Quartin… Quercellini, Quartin & LA, arXiv 0809.3675 LTB void model

  34. Munich 2008 Conclusions • Two solutions to the DE mismatch: either add “dark energy” or “dark gravity” • High-precision next generation cosmological observations are the best tool to test for modifications of gravity • It is crucial to combine background and perturbations • A full reconstruction to first order requires imaging and spectroscopy: Euclid

  35. Luca Amendola INAF/Osservatorio Astronomico di Roma The bright side of Munich Munich 2008

  36. Munich 2008 Weak lensing measures Dark Gravity scalar-tensor model Weak lensing tomography over half sky V. Acquaviva, L.A., C. Baccigalupi, in prep.

  37. Munich 2008 Non-linearity in WL =1000,3000,10000 Weak lensing tomography over half sky

  38. Munich 2008 Non-linearity in BAO Matarrese & Pietroni 2007

  39. Munich 2008 Conclusions: the teachings of DE • Two solutions to the DE mismatch: either add “dark energy” or “dark gravity” • The high precision data of present and near-future observations allow to test for dark energy/gravity • New MG parameters: γ,Σ • A general reconstruction of the first order metric requires galaxy correlation and galaxy shear • Let EUCLID fly...

  40. Munich 2008 References Basics: L.A. , Phys. Rev. D62, 043511, 2000; CMB: L.A. , Phys. Rev. Lett. 86,196,2001; Bias: L.A. & D. Tocchini-Valentini, PRD66, 043528, 2002 WMAP: astro-ph/0303228, Phys Rev 2003 N-body: A. Maccio’ et al. 2004 Dilatonic dark energy:L.A., M. Gasperini, D. Tocchini-Valentini, C. Ungarelli, Phys. Rev. D67, 043512, 2003

  41. Munich 2008 Current Observational Status: CFHTLS Hoekstra et al. 2005 Semboloni et al. 2005 Weak Lensing First results From CFHT Legacy Survey with Megacam (w=constant and other priors assumed) Type Ia Super- novae Astier et al. 2005

More Related