1 / 52

Structure formation in dark energy cosmology

Structure formation in dark energy cosmology. La Magia, April 2005. outline. Quintessence scheme Cosmological expansion rate Cosmological perturbations Cosmic microwave background Gravitational lensing Non-linear structure formation Quintessence, dark matter and gravity Conclusion.

loyda
Download Presentation

Structure formation in dark energy cosmology

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. Structure formation in dark energy cosmology La Magia, April 2005

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

  3. Quintessence scheme

  4. 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

  5. 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

  6. Cosmological expansion

  7. 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

  8. 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

  9. Cosmological perturbations

  10. 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)

  11. 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)

  12. 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

  13. 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)

  14. Cosmic microwave background

  15. Projection

  16. Integrated sachs-wolfe

  17. 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

  18. 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

  19. 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…

  20. Gravitational lensing

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

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

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

  24. CMB three-point correlation function from lensing

  25. CMB bispectrum l1 l3 l2

  26. CMB bispectrum

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

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

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

  30. Non-linear structure formation

  31. Galaxy clusters

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

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

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

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

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

  37. Dark energy records in galaxy cluster concentrations Klypin et al. 2003, Maccio et al. 2003, Dolag et al. 2004, …

  38. 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 Maccio 2004, Meneghetti et al. 2004

  39. Strong lensing arc statistics • A w > -1 dynamics in the dark energy makes the linear growth rate of perturbations behaving in the middle between an open and a LCDM universe • The number of giant arcs is a cosmological probe, which favours an open universe (Bartelmann 1999) Meneghetti et al. 2004

  40. Quintessence, dark matter and gravity

  41. Coupled quintessence • Coupling with baryons severely constrained by standard model physics • Dark matter coupling realized with exchange in the energy density (Amendola 2000), variable masses for dark matter particles (Matarrese et al. 2003)

  42. Extended quintessence • Relating gravity and dark energy through an explicit coupling with the Ricci scalar • Severely constrained on solar system scales • Cosmological bounds improving with incoming data

  43. Why weird cosmologies for the dark energy? • Is it a new component or the signature of a modification in known physics? • Coincidence unsolved • The couplings with dark matter or gravity may induce new attractor mechanism driving the dark energy density to the present abundance from a large set of initial conditions (Bartolo and Pietroni 2000, Tocchini-Valentini and Amendola 2000, Matarrese et al. 2004)

  44. Weird dark energy dynamics

  45. Weird dark energy dynamics

  46. Weird dark energy dynamics

  47. Saving the Quintessence from fine-tuning…again • Early universe attractors even for a cosmological constant behavior today (Matarrese et al. 2004) • Examples: attraction to general relativity (Bartolo and Pietroni 1999), the R-boost (Baccigalupi et al. 2000, Pettorino et al. 2005) • Consequences for the dark matter relic abundance (Catena et al. 2005)

  48. Perturbation behavior in weird cosmologies • Affecting geometry and perturbation growth rate • The mutual interaction between dark energy and other components may drastically change the behavior of dark energy evolution and perturbations • Spacetime variation of the gravitational constant, variable dark matter masses, scalar fields in galaxies, … Perrotta and Baccigalupi 2002, Wetterich 2002, Maccio et al. 2003, Perrotta et al. 2004, Amendola 2004, …

  49. Gravitational dragging Power injection on the dark energy density from other components Dark energy density fluctuations may be dragged to non-linearity by structure formation itself (Perrotta and Baccigalupi 2002) Non-linear structure formation in these scenarios largely unknown T[f ]mn;n=Qm , d T[f ]mn ;n=d Qm

  50. Conclusion: minimally coupled Quintessence • Linear perturbation behavior rather well understood • Non-linear perturbation behavior still poorly known (only clusters, nothing on larger scales, mergers, …)

More Related