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Cosmological structure formation and dark energy

Cosmological structure formation and dark energy. Carlo Baccigalupi Madrid, November 15, 2005. L. Cosmological Constant Problem. G µ ν =8 π T  ν. f. L. Cosmological Constant Problem. Geometry. G  ν +  g  ν =8 π T  ν + V g  ν. f. Quantum Vacuum. L.

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Cosmological structure formation and dark energy

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  1. Cosmological structure formation and dark energy Carlo Baccigalupi Madrid, November 15, 2005

  2. L Cosmological Constant Problem Gµν=8πTν f

  3. L Cosmological Constant Problem Geometry Gν+ gν=8πTν+Vgν f Quantum Vacuum

  4. L Cosmological Constant Problem : ? |-V|/M4Planck≈10-123 f 4 V: ? M Planck

  5. ?? L for Physics Two Why so small with respect to any particle physics scale ? ? f Why comparable to the cosmological matter density today

  6. outline • Quintessence scheme • Cosmological expansion rate • Cosmological perturbations • Cosmic microwave background • Gravitational lensing • Non-linear structure formation • Quintessence, dark matter and gravity • Conclusion

  7. Quintessence scheme

  8. The Quintessence: a minimal generalization of  • setting up a phenomenology of the impact of vacuum energy in cosmology • Predicting observable signatures if the acceleration is not due to a constant into the Einstein equations

  9. Quintessence tracking solutions • Classical trajectories for the Quintessence field converging to the present energy density from a large set of initial conditions • The field may (Wetterich 1988) or may not (Ratra-Peebles 1998) scale as the dominant component • Dark energy abundance today still severely tuned

  10. Where are we now? L Present constraints from CMB and LSS on the redshift average of the equation of state: -1.1 ≤‹w›z≤ -0.9 Quest to be continued, the study of the dark energy is one of the core topics of the Beyond Einstein (NASA) and Cosmic Vision (ESA) programs for the next decades… f

  11. Cosmological expansion

  12. Cosmological expansion rate • For a fixed value today, H is larger if w > -1 in the past • The comoving distance at a given redshift gets contracted • The redshift dependence of w is washed out by two redshift integrals

  13. Cosmological expansion rate • For a fixed value today, H-1 is larger if w > -1 in the past • The comoving distance at a given redshift gets contracted • The redshift dependence of w is washed out by two redshift integrals

  14. Cosmological perturbations

  15. Effects on cosmological perturbations • Modified geometry affects the growth of linear perturbations • The dark energy possesses fluctuations which are dragged on large scales by the background evolution (Brax & Martin 2000)

  16. Effects on cosmological perturbations • Modified geometry affects the growth of linear perturbations • The dark energy possesses fluctuations which are dragged on large scales by the background evolution (Brax & Martin 2000)

  17. Effects from modified geometry • For w greater than -1, the cosmological friction gets enhanced for a fixed H0 • This affects the linear density perturbations growth and the dynamics of the gravitational potentials on all scales in linear regime

  18. Effects from quintessence perturbations • A minimally coupled quintessence field is light, mf»(d2V/df2)1/2» H-1 • Fluctuations live on horizon and super-horizon scales • Excess power visible on small wavenumbers in the density power spectrum (Ma et al. 1999)

  19. Cosmic microwave background

  20. Projection

  21. Integrated sachs-wolfe

  22. Effects at decoupling • If the dark energy tracks the dominant component at a few percent level, the physics at decoupling is affected at a measurable level (early quintessence, see Caldwell et al. 2005 and references therein) • The equivalence epoch is shifted • The dark energy sound speed enters into the acoustic oscillations

  23. Constraining dark energy with primary CMB anisotropies • Main effect from the shift of acoustic peaks due to the variation of distances • The constraining power is limited by the projection degeneracy

  24. Constraining dark energy with primary CMB anisotropies • Assume flatness, fix H, gravitational waves in single field inflation • Fit with B98, COBE, MAXIMA, DASI, get some preference for a dynamical dark energy (Baccigalupi et al. 2002) • Mind degeneracies • Is WMAP Wtot=1.02±0.02 a similar indication? • Probably not…

  25. Gravitational lensing

  26. CMB lensing from structure formation

  27. Main predictions of CMB lensing

  28. Main predictions of CMB lensing

  29. Main predictions of CMB lensing Non-Gaussianity

  30. The promise of CMB lensing z z ≈ 1

  31. The promise of CMB lensing z acceleration z ≈ 1

  32. Weak lensing in dark energy cosmology • Probing intermediate redshifts only • Collecting effects from modified geometry and perturbations • Details in Acquaviva et al. 2004

  33. Breaking the projection degeneracy Dark energy records in lensed CMB, Acquaviva and Baccigalupi, 2005

  34. Breaking the projection degeneracy Dark energy records in lensed CMB, Acquaviva and Baccigalupi, 2005

  35. Probing dark energy with CMB B modes from lensing • B modes are lensing dominated at arcminute scales • The lensing picks up power at the onset of acceleration only • Cosmic variance is not simply Gaussian • Near future probes: EBEx, Quad, Clover, …

  36. CMB three-point correlation function from lensing

  37. CMB bispectrum l1 l3 l2

  38. CMB bispectrum

  39. Lensing chronology Giovi et al. 2003, PhD thesis

  40. CMB three-point statistics and dark energy Giovi et al. 2003, 2005, PhD thesis

  41. CMB three-point statistics and dark energy Giovi et al. 2003, 2005, PhD thesis

  42. Non-linear structure formation

  43. Galaxy clusters

  44. Matthias Bartelmann Massimo Meneghetti Klaus Dolag Carlo Baccigalupi Viviana Acquaviva Francesca Perrotta Lauro Moscardini

  45. Matthias Bartelmann Massimo Meneghetti Klaus Dolag Carlo Baccigalupi Viviana Acquaviva Francesca Perrotta Lauro Moscardini Heidelberg

  46. Matthias Bartelmann Massimo Meneghetti Klaus Dolag Carlo Baccigalupi Viviana Acquaviva Francesca Perrotta Lauro Moscardini MPA, Garching

  47. Matthias Bartelmann Massimo Meneghetti Klaus Dolag Carlo Baccigalupi Viviana Acquaviva Francesca Perrotta Lauro Moscardini SISSA, Trieste

  48. Matthias Bartelmann Massimo Meneghetti Klaus Dolag Carlo Baccigalupi Viviana Acquaviva Francesca Perrotta Lauro Moscardini Bologna

  49. Dark energy records in galaxy cluster concentrations Dolag et al. 2004

  50. Strong lensing arc statistics • Numerical ray tracing machines integrate null geodesics across structures out of N-body codes • Internal parameters of structures may be constrained through the lensing pattern Meneghetti et al. 2004

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