Cosmology … after 3 years of WMAP CMB data Rachel Bean Cornell University 1/41 Annual Theory Meeting , Durham December 2006 Plan o Introduction to CMB temperature and polarization o The maps and spectra o Cosmological implications 2/41 Annual Theory Meeting , Durham December 2006 What is WMAP? o NASA’s `Wilkinson Microwave Anisotropy Probe’ o Satellite detecting primordial photons “cosmic microwave background” 3/41 Annual Theory Meeting , Durham December 2006 CMB is a near perfect primordial blackbody spectrum Universe expanding and cooling over time… Kinney 1) Optically opaque plasma 3) ‘Free Streaming’ CMB 2) The ‘last scattering’ of photons Blackbody photons at ~3000K ~400,000 years after the Big Bang, redshifted by universe’s expansion -> ~2.726K today. 4/41 Annual Theory Meeting , Durham December 2006 The oldest fossil from the early universe Recombination CMB Nucleosynthesis Testable in particle accelerators Imprint in CMB Inflation and Grand Unification? Quantum Gravity/ Trans-Planckian effects…. 5/41 Annual Theory Meeting , Durham December 2006 The cosmic equivalent of tree rings… Dark Energy domination Imprint Reionization on CMB Galaxy formation Recombination CMB Nucleosynthesis Testable in particle accelerators Imprint in CMB Inflation and Grand Unification? Quantum Gravity/ Trans-Planckian effects…. 6/41 Annual Theory Meeting , Durham December 2006 Important comparisons with later observations Supernovae Dark Energy domination Weak lensing LSS surveys Imprint Reionization on CMB Galaxy formation Recombination CMB Nucleosynthesis Testable in particle accelerators Imprint in CMB Inflation and Grand Unification? Quantum Gravity/ Trans-Planckian effects…. 7/41 Annual Theory Meeting , Durham December 2006 Imperfections in the CMB are what we are really interested in o Photons escape from gravitational o …Translate into fluctuations in potential the blackbody photon temp at Cold spots = high density ~1/100,000 level Hot spots = low density "(x) x o Thomson scattering interactions in photon-electron/baryon fluid characteristic scale !~ cstrec # e - p+ Compton Coulomb scattering interaction 8/41 Annual Theory Meeting , Durham December 2006 CMB scattering gives a “2 for 1”: Polarization too! o Polarization created by Thomson Quadrupolar anisotropy scattering of photons Net linear polarization\ – Quadrupolar T distribution – T and P correlated e- Wayne Hu o P a purer imprint of early universe than T – Once electrons in atoms, scattering processes stop o P on scales below scattering horizon size Cold – small scale polarization at recombination z~1088 – Larger scale from reionization by the first stars z~25 Hot 9/41 Annual Theory Meeting , Durham December 2006 CMB Polarization: Alternative descriptions o Polarization <=> Stokes Parameters (Q,U) or E/ B modes analogous to EM. – E/B rotationally invariant and nicely E-mode divides underlying processes (curl free) o Density (scalar) perturbations only generate EE – EE polarization <=> matter density & CMB temperature B-mode (div free) o Metric (tensor) perturbations generate both EE and BB – BB insight into primordial gravity waves with little ‘contamination’ from scalar modes 10/41 Annual Theory Meeting , Durham December 2006 Plan o Introduction to CMB temperature and polarization o The maps and spectra o Cosmological implications 11/41 Annual Theory Meeting , Durham December 2006 Measure CMB at multiple frequencies to minimize systematics K (23 GHz) W(93 GHz) Ka (33 GHz) V (61 GHz) Our galactic plane Q (41 GHz) 12/41 Annual Theory Meeting , Durham December 2006 Multiple maps help extract galactic foregrounds ) K Ka Q V W K 100µ Synchotron CMB Anisotropy Free- Free 10 Dust Temperature ( 1 20 40 60 80 100 200 Frequency (GHz) Thermal Dust map Synchrotron map Free-free map CMB map 13/41 Annual Theory Meeting , Durham December 2006 Harmonic analysis of the maps gives deeper insight into underlying processes o Spherical harmonic decomposition of sky o For a random field all we need to describe it is the correlation function l=2 o Estimate Cl from sampling alm from the sky l=10 l=1000 o Inherent sampling error associated with measurement (“cosmic variance”) 14/41 Annual Theory Meeting , Durham December 2006 Spatial fluctuations transform into `angular power spectrum’ 15/41 Annual Theory Meeting , Durham December 2006 CMB Temperature fluctuations: An overview Decreasing length scale Acoustic oscillations • Photon- baryon fluid at last scattering Small scales : Damping tail • Scattering processes after recombination Largest scales • Only just entering causal horizon recently, sensitive to universe’s recent evolution • Cosmological origins • inherent sampling uncertainty “cosmic variance” 16/41 Annual Theory Meeting , Durham December 2006 3 years of data vs 1 year: 2 despite smaller error bars, the $ eff improves 2 $ eff (TT)/dof = 1.068 (1.09 yr 1) 2 $ eff (all)/dof = 1.04 (1.04 yr 1) 1 Year 3 Years 17/41 Annual Theory Meeting , Durham December 2006 Polarization maps 18/41 Annual Theory Meeting , Durham December 2006 Polarized foregrounds - evidence of role of galactic magnetic field Magnetic Field Structure in external galaxies exhibit spiral structure 19/41 Annual Theory Meeting , Durham December 2006 Summary of power spectrum results TT TE EE BB upper limit 20/41 Annual Theory Meeting , Durham December 2006 Plan o Introduction to CMB temperature and polarization o The maps and spectra o Cosmological implications 21/41 Annual Theory Meeting , Durham December 2006 Observations have driven many key theoretical developments An expanding universe Homogeneity and isotropy Galaxy outer rotation An accelerating on large scales velocities universe Hot Big Bang Inflation Dark matter Dark energy 22/41 Annual Theory Meeting , Durham December 2006 Observations have driven many key theoretical developments An expanding universe Homogeneity and isotropy Galaxy outer rotation An accelerating on large scales velocities universe Hot Big Bang Inflation Dark matter Dark energy Solutions create many unanswered questions in themselves! What are the What causes inflation? What is dark matter? What is dark energy? implications for quantum (Planck) scale physics? Can we find the dark Are current and matter in ground based inflationary era experiments? expansion related? 23/41 Annual Theory Meeting , Durham December 2006 CMB peaks, troughs and plateaus constrain cosmology ) 2 K µ ( m u r t c CMB spectrum features e p S are translated into core r e w cosmological parameters o P ( ( Angular scale l The expansion history: Hubble expansion factor H0, H(z) The matter content curvature : fractional energy densities (%X=&X/&total) Primordial power spectrum : P(k) = A kn-1, tensor to scalar ratio r Dark energy characteristics : equation of state, w=density/pressure Ionization history : optical depth ('), redshift of reionization(zrei) 24/41 Annual Theory Meeting , Durham December 2006 First peak position key constraint on the matter contents of the universe o E.g. CMB First peak position - angular diameter distance to last scattering ) 2 K µ ( Sound horizon ) at z=1100 o Depends on matter content (expansion history) Power Spectrum (( o Depends on curvature Angular scale l – BUT Geometrical degeneracy o Degeneracies BIG hurdle to get to theory Last – Polarization data helps break these!g scattering surface ) Comoving distance Passage of rays to last scattering in curved space 25/41 Annual Theory Meeting , Durham December 2006 Improvement in Parameters from polarization measurement of reionization (') Comparison of 1st year and 3rd year WMAP constraints s f n o o i 1.4 e t 1.2 i c s WMAP yr 1 d n n n e o 1.2 i o d WMAP yr 1 t c i n 1.1 d e l n p a 1.0 i o WMAP yr 1 WMAP yr 1 e t c d i + other CMB + other CMB n l 1.0 i 0.8 e a l i f a t i o c WMAP 3 yr WMAP 3 yr n S i e 0.6 0.9 z i 0.1 0.12 0.14 0.16 0.18 0.2 0. 0.1 0.2 0.3 0.4 0.5 S Amount of matter ', opacity of reionization 26/41 Annual Theory Meeting , Durham December 2006 Improvement from additional complementary datasets e+2' n s ns 2 2 +2' %bh %bh e e+2' h h 2 % As %ch m n n s As s 2 As %bh *8 27/41 Annual Theory Meeting , Durham December 2006 The simple 6 parameter cosmological model 2 2 2 {%bh , %mh , h, ', ns, As}: $ /dof = 1.04 Angular scale 900 0 0 0.20 ) 2 0.5 2 6000 o Run model forward in time K µ ( – predict cosmological evolution , 40002 / l C o Go backwards in time ) 1 TT + l – to study early universe 2000( l o Constrain variants on simplest model 0 TE – massive neutrinos ) 2 2 K – Dark energy models µ ( – Beyond power law inflation , 1 2 / l TE C ) 1 0 + l ( -1 10 100 500 1000 Multipole moment, l 28/41 Annual Theory Meeting , Durham December 2006 WMAP fits predict Hubble expansion H(z) 1 - s Predicted H(z) m k evolution 1 - c HST p M ) Synthetic stellar pop z ( Ages of galaxies H (Simon et al ‘05) z Luminosity distance prediction from WMAP alone SNLS HST/GOODS z z 29/41 Annual Theory Meeting , Durham December 2006 WMAP fits predict galaxy & mass distribution Predicted P(k) for SDSS and 2dF galaxy surveys from WMAP alone ] 3 ) c p M / h ( [ ) k ( P k (h/Mpc) k (h/Mpc) 30/41 Annual Theory Meeting , Durham December 2006 WMAP fits predict small scale CMB Predicted small scale CMB spectrum from WMAP alone 31/41 Annual Theory Meeting , Durham December 2006 Constraints on VERY early universe o `Inflation’ – early period of accelerated expansion, just Inflation after the Big Bang V(-) Reheating o Acceleration induced by slow roll of particle - down a potential well V(-) o Predicts … (n -1) – No preferred scale P(k) ~k with n-1~0 - – Small tensor contribution r=T/S – Entropy conserving (adiabatic) fluctuations o Acceleration causes Hubble horizon decrease – Stretches space -> spatial Flatness – Density fluctuations random (Gaussian) 32/41 Annual Theory Meeting , Durham December 2006 Constraints on geometry of the universe CMB needs dark matter: % - alternative 10-54 less likely! .