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Current and Future Constraints on Models of Cosmic Acceleration

Current and Future Constraints on Models of Cosmic Acceleration. Jochen Weller Universitäts-Sternwarte München – LMU Excellence Cluster for “Origin and Structure of the Universe” Max-Planck Institute for Extraterrestrial Physics. The Cosmic Pie. Baryons. Dark Matter. Dark Energy.

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Current and Future Constraints on Models of Cosmic Acceleration

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  1. Current and Future Constraints on Models of Cosmic Acceleration Jochen Weller Universitäts-Sternwarte München – LMU Excellence Cluster for “Origin and Structure of the Universe” Max-Planck Institute for Extraterrestrial Physics 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  2. The Cosmic Pie Baryons Dark Matter Dark Energy 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  3. The Hubble Diagram with Type Ia Supernovae 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  4. Physics Nobel Prize 2011 Saul Perlmutter Brian P. Schmidt Adam G. Riess The Nobel Prize in Physics 2011 was divided, one half awarded to Saul Perlmutter, the other half jointly to Brian P. Schmidt and Adam G. Riess "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae". Probe Studium - September 2012

  5. Consequences of SNe Observation • for Friedman-Robertson-Walker metric (homogenous and isotropic) + data: ä > 0 • accelerated expansion • from Einstein equations: ä ~ -(+3p) • need: p<-/3 • ‘normal’ matter has: p≥0 • we know vacuum energy or cosmological constant has: p=- 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  6. Other Observations … 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  7. Cosmic Microwave Background • First peak corresponds to sound horizon at last scattering Angular scale of 1st peak can be compared to angular diameter distance at z=1100  universe is very close to flat (together with H0) 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  8. Measuring the Distribution of Galaxies • Large scale distribution of galaxies is a test for the growth of structures in the Universe • measure with power spectrum 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  9. Large Scale Structure – Baryon Accoustic Oscillations • Pressure waves in photon-baryon fluid are frozen in at recombination • Dark matter responds to overdensity in baryons • imprint on dark matter power spectrum • known scale: standard rulers • cosmology Percival et al. 2007 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory physical scale: 148 Mpc

  10. How much vacuum energy? Union II analysis • Energy densities in the Universe: • Radiation (from CMB temperature): r ≈ 510-5 • combine SNe & CMB: • matter: m≈ 0.28(baryons: ≈ 0.04; [BBN/CMB] • cosmological constant: ≈ 0.72(space is close to flat) 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  11. What is the problem with the cosmological constant ? • “Expected” value from Planck scale:  1078 (GeV)4 • Measured value 10-45 (GeV)4 • Why is << (TeV)4 ? • Why m ? radiation ~ 1/a4 log  matter ~ 1/a3 cosmological constant { { { log a radiation dominated matter dominated vacuum dominated cosmological constant ≅ vacuum energy (Zel’dovich) 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  12. If not , what else? • dynamical dark energy • general fluid • scalar field (Quintessence, k-essence, ...) • dark energy from defects (solid dark energy) • modifications of General Relativity on large scales • Extra dimensions and brane worlds (DGP) • f(R) • more exotic modifications: f(R, RR, RR) • apparent effect; “backreaction” from small scale inhomogeneities 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  13. Deceleration parameter (flat Universe, only DE): Dark Energy simple fluid: p = w Hence accelerated expansion for w<-1/3 ! Cosmological constant: w=-1 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  14. Equation of state of scalar field: Quintessence Dynamical dark energy 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  15. 1st try (Wetterich, Ratra and Peebles 1988, Ferreira and Joyce 1998): Ferreira & Joyce 1998 Quintessence attractor, hence NO FINE TUNINGrequired ! but: attractor in regime: de< m! 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  16. 2nd try (Steinhardt, Caldwell et al. 1998): Zlatev et al. 1998 tracker solution ! 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  17. scalar field dark energy models (quintessence) w = p/ Different Quintessence Models All models ad hoc 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  18. Constraints on w from Union II Analysis w = -0.997±0.051 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  19. Constraints on Evolution of w w = w0+wa(1-a) = w0+waz/(1+z) 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  20. SDSS-III DR9: BOSS - CMASS Sanchez et al. 2012 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  21. However, do we really need dark energy to explain cosmic acceleration ? 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  22. Maybe gravity is standard at short distances... Gravity still sucks 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  23. but gets modified on large distances ... 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  24. Example for Modified Gravity Model - DGP • Brane-world inspired scenario • large extra dimension • Standard model confined to the brane • Gravity can leak of the brane into 5th dimension - cross over scale rc • Modification of Friedman equations • Theoretical consistency of accelerated branch of DGP doubtful Dvali, Gabadadze, Porrati 2000 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  25. Geometric Degeneracy • Arbitrary dark energy model with suitable chosen equation of state w(a) can mimic expansion history of any mDGP model • α= 0 is ΛCDM (w = -1) • α=1 is DGP with w = -0.78+0.32(1-a) Dvali & Turner 2003 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  26. Growth of structures in modified gravity δ: overdensity modified gravity From large scale structure point of view G is varying in time on large scales 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  27. The Growth Factor • Growth can break degeneracy between mDGP and dark energy • Possible growth probes • weak lensing • galaxy cluster counts • redshift space distortions 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  28. Weak Lensing • deflection angle • Statistical distortion of galaxies • Small 1% shear • Given by integrated mass along line of sight • Direct probe of matter distribution 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  29. Combined Constraints CFHTLS+SNe+BAO all angular scales α<0.86 (95% C.L.) α<0.91 (95% C.L.) DGP marginally ruled out Thomas, Abdalla, Weller 08 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  30. Constraining Growth with CFHTLS Thomas, Abdalla, Weller 08 General Relativity:γ= 0.55 DGP: γ= 0.65 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  31. Extending Gravity – The Scaleron Modification of Gravity Asymptotic behaviour of valid models Cosmological Constant Additional Scalar Degree of Freedom: Scaleron 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  32. The Scaleron Mass Thomas, Appleby and Weller 2011 Parameterize Scaleron Mass M0 and its decay rate ν 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  33. Effect on the Linear Power Spectrum solid: ΛCDM dashed: M0-1 = 375 × 1028 h-1 eV-1 ν= 1.5 top: z=0 bottom: z=1.5 Thomas, Appleby and Weller 2011 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  34. Galaxy Clusters as a Probe of Structure Formation • If linear density perturbation exceeds threshold density the region will collapse and form a cluster • Mass function; density of clusters at a given mass and redshift • Mass function sensitive to amplitude of perturbations (8 ) and mass contents of the Universe (m ); but also other cosmological parameters (w) ! 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  35. more low redshift clusters more low mass clusters Counting Halos in Simulations • Count halos in N-body simulations • Measure “universal” mass function - density of cold dark matter halos of given mass Almost exponential dependence on growth of structures Jenkins et al. 2002, Tinker et al. 2008 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  36. Observation of Galaxy Clusters • x-ray signature of intra-cluster gas • Sunyaev-Zel’dovich decrement in effective temperature of cosmic microwave background photons • weak and strong lensing • Member galaxies • counting • spectroscopy 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  37. The Non-Linear Domain • Important for Clusters and LSS at “smaller” scales • Oyaziu et al. 2008 • MGADGET – Puchwein, Baldi, Springel, Amendola and Weller in preparation • Including Baryons and Hydro (e.g. AGN feedback) 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  38. Constraints on f(R) from X-ray Data Schmidt et al. 2009 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  39. Current Constraints on ‘higher order’ gravity • SNe, BAO, Hubble • CMB, WL, galaxy flows • Cluster Abundance: • galaxy-galaxy lensingof MaxBCG clusters andgroups: three mass binsand two redshift bins Lombriser, Slosar, Seljak & Hu 2010 B0 ~ m-1 mass of additional scalar degree of freedom of gravity 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory Uses SDSS maxBCG catalog

  40. What to measure ? • How much dark energy today ? • Difference from a cosmological constant ? • Signatures of Modified Gravity ? • Signatures of Backreaction or Inhomogeneous Universe ? • Clumping of dark energy ? 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  41. The Dark Energy Survey Blanco 4-metre at CTIO • Survey project using 4 complementary techniques: • Cluster Counts: 100,000 out to z>1; Synergy with SPT and VHS • Weak Lensing: Shape Measurement of 300 million galaxies • Large-scale Structure: 300 million galaxies to z=1 and beyond • Supernovae: 4000 SNe out to z=1 • Two multiband surveys: • 5000 deg2grizYto 24th mag • 30 deg2 repeat (SNe) • New 3 deg2 FOV camera and Data management system • Survey 2012-2017 (525 nights • Facility instrument for Blanco 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  42. DES – Survey Area 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  43. DES – First Light Dear Colleagues, We are very happy to announce that the Dark Energy Camera achieved its first light images (through the g, r, and Y filters) on the Blanco telescope tonight (around 2 am September 12 UT). Although there are many tests and adjustments to be done during commissioning, so far the instrument appears to be working very well and has already delivered round 1.2 arcsec images in its first couple of hours of operation … Fornax Cluster Galaxies NGC 1365 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  44. EUCLID: An ESA Cosmic Vision Mission Adopted by ESA June 2012 Shapes and photo-z of 2×109 Galaxies z of 2×107 Galaxies Euclid RB: arXiv 1110.3193 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  45. EUCLID Probes • Wide: 15,000 deg2; Deep: 40 deg2 • Weak Lensing • Diffraction limited galaxy shape measurements in one broad visible R/I/Z band. • Redshift determination by Photo-z measurements in 3 YJH NIR bands to H(AB)=24 mag • BAO • Spectroscopic redshifts (NIR) for 33% of all galaxies brighter than H(AB)=22 mag, σz<0.001 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  46. Dark Energy and Modified Gravity with EUCLID Euclid RB: arXiv 1110.3193 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  47. Euclid Forecasts on Scaleron outer contours: linear scales only (l<400) inner contours: non-linear scales (l<10000) Thomas, Appleby and Weller 2011 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  48. Euclid and Galaxy Clusters maxBCG eRosita Euclid 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  49. Conclusions • Accelerated Expansion of the Universe is established • Concordance model with about 70% in dark energy • Constant equation of state is homing in on cosmological constant at the 5% level. • Evolution in w currently not significantly constraint • No constraints on deviations from dark energy scenario with current data (modified gravity, exotic fluids, backreaction) 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

  50. Conclusions II • Next Generation Dark Energy Probes (like DES) will push constraint on w below 2% and begin to constrain evolution in w • EUCLID mission will allow to differentiate different cosmic acceleration scenarios and dark energy models (evolution in w, different growth) 9th Vienna Central European Seminar on Particle Physics and Quantumn Field Theory

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