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The WMAP Results and Cosmology

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The WMAP Results and Cosmology The WMAP results and cosmology Rachel Bean Cornell University SLAC Summer Institute July 19th 2006 Rachel Bean : SSI July 29th 2006 1/44 Plan o Overview o Introduction to CMB temperature and polarization o The maps and spectra o Cosmological implications Rachel Bean : SSI July 29th 2006 2/44 What is WMAP? o Satellite detecting primordial photons “cosmic microwave background” Rachel Bean : SSI July 29th 2006 3/44 Science Team C. Barnes (Princeton) N. Odegard (GSFC) R. Bean (Cornell) L. Page (Princeton) C. Bennett (JHU) D. Spergel (Princeton) O. Dore (CITA) G. Tucker (Brown) M. Halpern (UBC) L. Verde (Penn) R. Hill (GSFC) J. Weiland (GSFC) G. Hinshaw (GSFC) E. Wollack (GSFC) N. Jarosik (Princeton) A. Kogut (GSFC) E. Komatsu (Texas) M. Limon (GSFC) S. Meyer (Chicago) H. Peiris (Chicago) M. Nolta (CITA) Rachel Bean : SSI July 29th 2006 4/44 Plan o Overview o Introduction to CMB temperature and polarization o The maps and spectra o Cosmological implications Rachel Bean : SSI July 29th 2006 5/44 CMB is a near perfect primordial blackbody spectrum Universe expanding and cooling over time… Kinney 1) Optically opaque plasma photons scattering off electrons 3) ‘Free Streaming’ CMB Thermalized (blackbody) photons at 2) The ‘last scattering’ of photons ~6000K diluted and redshifted by ~300,000 years after the Big Bang, universe’s expansion -> ~2.726K neutral atoms form and photons stop background we measure today. interacting with them. Rachel Bean : SSI July 29th 2006 6/44 The oldest fossil from the early universe Recombination CMB Nucleosynthesis Processes during opaque era imprint in CMB fluctuations Inflation and Grand Unification? Quantum Gravity/ Trans-Planckian effects…. Rachel Bean : SSI July 29th 2006 7/44 The cosmic equivalent of tree rings… Dark Energy domination Processes following recombination imprint Reionization on CMB Galaxy formation Recombination CMB Nucleosynthesis Imprint in CMB Inflation and Grand Unification? Quantum Gravity/ Trans-Planckian effects…. Rachel Bean : SSI July 29th 2006 8/44 Important comparisons with later observations Supernovae Dark Energy domination Weak lensing LSS surveys Imprint Reionization on CMB Galaxy formation Recombination CMB Nucleosynthesis Imprint in CMB Inflation and Grand Unification? Quantum Gravity/ Trans-Planckian effects…. Rachel Bean : SSI July 29th 2006 9/44 Imperfections in the CMB are what we are really interested in o Escape of photons from evolving o …Translate into fluctuations in gravitational potential wells at last the blackbody photon temp at scattering, ~1/100,000 level Cold spots = high density Hot spots = low density "(x) x o Thomson Scattering interactions in photon-electron/baryon fluid characteristic scale !~ cstrec # e - p+ Compton Coulomb scattering interaction Rachel Bean : SSI July 29th 2006 10/44 CMB “Power Spectrum” Cosmological fluctuations o Decompose map into functions with fluctuations on different angular scales (denoted by l) l=2 l=10 CMB Temperature Power Spectrum l=1000 l h c a e t a ” r e w o Plot a graph of the weight o P (importance) each function has in the “ map – “the Power spectrum” ~220 Angular scale l Rachel Bean : SSI July 29th 2006 11/44 CMB scattering gives a “2 for 1”: Polarization too! o Polarization created by Thomson scattering of photons with a non-zero Isotropic radiation quadrupole (l=2 spherical harmonic) No polarization - o Polarization gives a purer imprint of early e universe than temperature Dipolar anisotropy – Once electrons in atoms scattering No polarization processes stop - o Polarization on scales below horizon scale e at scattering Quadrapolar anisotropy – small scale polarization at Net linear polarization! recombination z~1088 – Larger scale from reionization by the first stars z~25 e- Rachel Bean : SSI July 29th 2006 12/44 Based on Wayne Hu’s figures Temperature & polarization patterns correlated radial polarization pattern Cold around cold spots matter flows into high density region tangential polarization pattern around hot spots Hot low density regions which matter flows out of o Polarization pattern <-> velocity flow of matter from high to low density – Predicts polarization should $ out of phase with temperature Rachel Bean : SSI July 29th 2006 13/44 CMB Polarization: Alternative descriptions o Polarization <=> Stokes Parameters (Q,U) or E/ B modes analogous to EM. – E/B independent of axis choice and nicely divides underlying processes o Scalar perturbations only generate EE – EE polarization <=> matter density E-mode & CMB temperature (curl free) o Only tensor perturbations can generate both EE and BB – BB insight into primordial gravity waves with little ‘contamination’ B-mode from scalar modes (div free) Rachel Bean : SSI July 29th 2006 14/44 Plan o Overview o Introduction to CMB temperature and polarization o The maps and spectra o Cosmological implications Rachel Bean : SSI July 29th 2006 15/44 Temperature maps Rachel Bean : SSI July 29th 2006 16/44 Multiple maps help extract CMB from galactic contaminants K Ka Q V W ) K µ Thermal Dust ( S 100 y CMB Anisotropy e nc IR maps from COBE, r h Synchroton emission u ot t IRAS and extrapolate F ro - Acceleration of cosmic ray a r n 1.6 r e e- ~ % e F st electrons in magnetic fields p r ee Du of type 1b and type 2 SN m 10 e remnants and from diffuse T µG magnetic field in the galaxy - Complicated frequency and 1 source dependence, rough 20 40 60 80 100 200 dependence~ %&2.5 &%&3.1 Frequency (GHz) Free- free emission Spinning dust grains? &2.15 No detections reported -Electron-ion scattering ~ % Expect strict cutoff ~40GHz -Use large scale H' (H n=3->2) maps to estimate spatial contribution As well as remove other systematics e.g. 1/f noise from Rachel Bean : SSI July 29th 2006 17/44 detectors 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 Rachel Bean : SSI July 29th 2006 18/44 Polarization maps Rachel Bean : SSI July 29th 2006 19/44 Polarized foregrounds - evidence of role of galactic magnetic field Magnetic Field Structure in external galaxies exhibit spiral structure Rachel Bean : SSI July 29th 2006 20/44 Same bisymmetric spiral pattern is a good global fit to the field structure Polarization angle Polarization Amplitude Rachel Bean : SSI July 29th 2006 21/44 ‘Cleaning’ out foregrounds o Low frequency (K band) synchrotron profile of galaxy magnetic field + Multi-frequency dust map and starlight polarization measurements =a template to clean maps o Many people interested in galactic polarization o but for cosmologists they are contamination! Rachel Bean : SSI July 29th 2006 22/44 Summary of power spectrum results TT TE EE BB upper limit Rachel Bean : SSI July 29th 2006 23/44 Talk plan o Overview o Introduction to CMB temperature and polarization o The maps and spectra o Cosmological implications Rachel Bean : SSI July 29th 2006 24/44 Cosmological input assumptions o GR using Einstein’s equations o Initial conditions from inflation - More later Gµ% = 8$ G Tµ% c4 o Atomic processes at recombination - Thomson scattering - Atomic transitions o Homogeneity and isotropy using Friedmann equations o Explicit properties of matter/space - Standard particle model - Cold Dark matter - Cosmological constant - Spatial flatness …. "The least questioned assumptions are often the most questionable” Pierre Paul Broca Rachel Bean : SSI July 29th 2006 25/44 Cosmological Inference and Degeneracy Universe’s relative CMB Temperature Power Spectrum Matter to radiation ratio *m/*# size today to when 2 Baryon fraction *bh CMB was formed (*m, ) Reionization , *+, h) 2 K µ Initial conditions ns,As ( r e w Geometry of the o P universe (*k) T T 2 Baryon fraction *bh Dark Energy (* +) Initial conditions ns Initial conditions ns Angular scale l ) 2 K µ ( r e w o P Large scale E polarization from ) reionization Wayne Hu’s website Angular scale l Rachel Bean : SSI July 29th 2006 26/44 Summary A simple cosmological model with only 6 parameters fits the WMAP data 2 2 2 {*bh , *mh , h, ,, ns, As} => ( /dof = 1.04 Angular scale 900 20 0.50 0.20 6000 ) 2 o Run model forward in time K µ ( – predict cosmological evolution $ 4000 2 / l C ) TT o Go backwards in time 1 + l 2000 ( – to study early universe l TE o Constrain variants on simplest 0 model ) 2 2 K – open universe, µ ( 1 – massive neutrinos $ 2 / TE – Dark energy models l C ) – Beyond power law inflation 1 0 + l ( -1 10 100 500 1000 Rachel Bean : SSI July 29th 2006 27/44 Multipole moment Improvement in Parameters Comparison of 1st year and 3rd year LCDM constraints 1.4 1.2 WMAP yr 1 1.2 WMAP yr 1 1.1 -8 ns 1.0 WMAP yr 1 WMAP yr 1 + other CMB + other CMB 1.0 0.8 WMAP 3 yr WMAP 3 yr 0.6 0.9 0.1 0.12 0.14 0.16 0.18 0.2 0. 0.1 0.2 0.3 0.4 0.5 2 *mh , Rachel Bean : SSI July 29th 2006 28/44 Likelihood Analysis of Optical Depth o Polarization data alone gives important information about reionization 2 – ,= 0 => .( eff = +8 vs bestfit ,>0 d o o h i l o More years of data will yield more insights e k EE only into reionization e.g. 2 step process? i L (QV) – xe = 1 for z<7 KaQVW 0 – xe = xe for 7<z<zrei => 0.057<,<0.17 (1-) , 0 0 xe xe Rachel Bean : SSI July 29th 2006 29/44 zrei ns WMAP fits predict H(z) 1 - s Predicted H(z) m evolution k 1 - HST c 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 Rachel Bean : SSI July 29th 2006 30/44 WMAP fits predict galaxy and 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) Rachel Bean : SSI July 29th 2006 31/44 WMAP fits predict primordial abundances (Steigman et al 2005) Rachel Bean : SSI July 29th 2006 32/44 Predictions of inflation o Acceleration induced by slow roll Inflation down scalar potential V(/) – Near scale invariant tilt – Small but non-zero tensor Reheating contribution r=T/S o Acceleration causes Hubble horizon decreases m 2 V’’ / 0 = p << 1 – Flatness is an attractor 8$ V – Density fluctuations seeded by m 2 V’ 2 Gaussian quantum fluctuations 1 = p << 1 16$ V 2 ns =1-61+20 Rachel Bean : SSI July 29th 2006 33/44 WMAP and Initial Conditions : constraining inflation n-1 Constraints on power law initial P(k)2k + tensors, r=AT/AS WMAP WMAP + SDSS ) c p M / 2 0 0 .
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