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 Hot pattern around hot spots 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
,
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 . 0 k= ( r
) WMAP + 2dF WMAP + CBI+VSA c p M / 2 0 0 . 0 k= ( r
ns(k=0.002/Mpc) ns(k=0.002/Mpc) Rachel Bean : SSI July 29th 2006 34/44 Alternative power spectrum models
Sharp k cutoff in initial spectrum Improvements again small, power law P(k) fits the data well x a m L / L P(k)= 0, k -4 -1 2 kc [10 Mpc ] .( eff =-22 Rachel Bean : SSI July 29th 2006 35/44 Geometry of the universe *+ WMAP WMAP +HST +LRGs *+ WMAP WMAP WMAP only +SNLS +HST/GOODS 2 No CDM .( eff =+248 No + .(2 =0 (H ~30) eff 0 *+ WMAP WMAP +2dF +SDSS *m *m Rachel Bean : SSI July 29th 2006 36/44 Massive neutrinos 3mv (eV) 95% CL WMAP WMAP+SDSS WMAP only 2.0 WMAP+SDSS 0.93 WMAP+2dF 0.90 -8 CMB +LSS + SN 0.68 3mv (eV) Rachel Bean : SSI July 29th 2006 37/44 Dark Energy 2 Clustering dark energy cs =1 w!-1 Ignoring fluctuations in DE w w w w WMAP WMAP WMAP WMAP WMAP+SDSS WMAP+2dF WMAP+SDSS WMAP+2dF *m *m *m *m w w w w WMAP WMAP WMAP WMAP WMAP+SN WMAP+SN WMAP+SN WMAP+SN (HST/GOODS) (SNLS) (HST/GOODS) (SNLS) *m *m *m *m Sensitive to assumptions about clustering properties of Dark Energy Rachel Bean : SSI July 29th 2006 38/44 Robustness of dark energy constraints.... w + curvature CMB + SN + LSS w + massive neutrinos w CMB + SN + LSS w *k 3mv (eV) Rachel Bean : SSI July 29th 2006 39/44 Beyond WMAP : Applying WMAP to new tasks o Cross-correlation with structure : – Exciting opportunities to probe dark energy, reionization … o Complementary cosmological experiments – Crucial complementary parameter constraints from precise understanding of physics at last scattering o Future CMB experiments: APEX – Mapping the foregrounds CTIO ACT – Calibration (DES) Planck ALMA Rachel Bean : SSI July 29th 2006 40/44 Small scale CMB / SZ surveys Implications for dark matter/ dark energy research o Ground based e.g.: APEX –SZA ~100 clusters, 12 sqdeg, z~1, 2004 –APEX ~1000, 200sqdeg, 2005 ACT –ACT ~1000 clusters, 100 sqdeg, z~1.4, CTIO (DES) early 2006, photometric support from SALT –SPT ~10,000 clusters, 4,000 sqdeg, z~1.2, 2007, photometric support from DES Planck o Satellite : • Planck, ~ 15,000 clusters, z~1, 2007 ALMA o And others … Rachel Bean : SSI July 29th 2006 41/44 CMB polarization large and small scale: Primordial gravity waves & CMB lensing … Experiment Location Status Experiment Location Status PIQUE Ground Observing EBEX Balloon Building WMAP L2 Observing BICEP Ground Observing DASI Ground Observing Quest Ground Building CBI Ground Observing Maxipol Balloon Analyzing QUAD Ground Observing Planck L2 Building Amiba Ground Building Clover Ground Funded QUAD Planck BICEP Rachel Bean : SSI July 29th 2006 42/44 Ground based DIRECT detections vital counterpart o Astrophysical sources detected on earth – Temper and test indirect observations o Dark matter searches – CDSM - Soudan Mine, Minessota , US – UKDMC Boulby Salt Mine, Yorkshire ,UK – DAMA Gran Sasso underground lab, Italy o LHC – Beyond the standard model – Existence of extra dimensions – Do scalar particles exist? Rachel Bean : SSI July 29th 2006 43/44 Conclusions o WMAP now has full sky temperature and polarization maps – Polarization reionization signature breaks cosmological degeneracies – Simple +CDM cosmological model has survived its most rigorous test – Starting to constrain inflationary parameter space o Rich prospects from combining/ correlating WMAP with other complementary data o Future CMB polarization experiments promise of the universe when it was a trillionth of a second old o Direct measurement on earth of dark matter particles / extra dimensions and a scalar particle will play a crucial role in progressing theoretical understanding Rachel Bean : SSI July 29th 2006 44/44