bologna, 27 aprile 2006 wmap – 3-year results fabio finelli inaf/oab & inaf/iasf-bo lauro...
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Bologna, 27 Aprile 2006
WMAP – 3-year results
Fabio Finelli
INAF/OAB & INAF/IASF-BO
Lauro Moscardini
Dip. Astronomia UniBo
Bologna, 27 Aprile 2006
1. WMAP 1st year papers 2. WMAP 3rd papers
3. A. Lewis, astro-ph/0603753
4. Planck Bluebook, astro-ph/0604069
5. Wayne Hu’s webpage: http://background.uchicago.edu/whu
SOURCES
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WMAP
• WMAP: spinning (~0.5 rpm), precessing satellite orbiting L2
• dual Gregorian (1.4×1.6m) mirror system
• passively cooled to <95K
• radiometers measuring phase and amplitude of incoming waves
• Proposed in 1995; selected in 1996; launched in june 2001; possibly 8-years mission
• 13 papers in 2003, 7311 citations up today
• 4 new papers in march 2006, 160 citations up today
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Channels
• frequencies: 22, 30, 40, 60, 90 GHz (3.3 to 13.6 mm wavelength)
• resolution: 0.23-0.93 degrees
• sensitivity: ~35µK per 0.3×0.3 degree pixel
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Channels
• frequencies: 22, 30, 40, 60, 90 GHz (3.3 to 13.6 mm wavelength)
• resolution: 0.23-0.93 degrees
• sensitivity: ~35µK per 0.3×0.3 degree pixel
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Sky Maps
foregrounds:synchrotron,dust,free-freeemission
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Temperature Map
• foreground subtraction: spectra differ from the CMB's Planck spectrum
• comparison of signals from different channels
• fitting of foreground templates
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Power-Spectrum Analysis
• subtraction of mean temperature; relative temperature fluctuations
• expansion into spherical harmonics; coefficients acoefficients a
lmlm
• power spectrumpower spectrumCCll=<|a=<|a
lmlm||22>> , related to the
matter power spectrum P(k)
• principal effects:
– Sachs-Wolfe effect
– acoustic oscillations
– Silk damping
Bologna, 27 Aprile 2006Courtesy by W. HuCourtesy by W. Hu
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Mechanisms for anisotropies
density:density: adiabatic process compression increases T, while expansion decreases T
gravity:gravity: gravitational red- or blue-shift
velocity:velocity: Doppler effect
Different contributions must be summed up
Primary anisotropies:Primary anisotropies: produced on the last scattering surface
Secondary anisotropies:Secondary anisotropies: produced along the trajectory to the observer
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On scales larger than the horizon (i.e. large angles, small l)
Velocity can be neglected (dipole), microphysics too, gravity wins against density!
Temperature fluctuations are directly proportional tothe gravitational potential: Sachs-Wolfe effectSachs-Wolfe effect
Notice: overdensity are colder than average!
Already observed by COBE in 1991!
Good estimates for amplitude and slope of P(k),but problems of cosmic variance
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The cosmological parameters (I):the density parameters i
• Matter: m
• Dark energy: DE (w P/ c2=-1 is the cosmological constant ; w -1 is the quintessence)
• Baryons: b
• Curvature: K=1 - i
• Total: 0 =1- K
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The cosmological parameters (II):the spectral parameters
Standard inflationary models predict that primordial fluctuations are
• Gaussian• Adiabatic• Scale invariant, i.e. with logarithmic slope of the
power spectrum n=1: P(k)=A kn
The amplitude A is usually expressed in terms of the variance computed on a scale of 8 Mpc/h: 8
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The cosmological parameters (III):the other ones
• The Hubble constant HHubble constant H00 and its redshift evolution: measures the expansion rate of the universe and enters the distance definitions
• The optical depth The optical depth : it is related to the probability that a CMB photon with an electron along the trajectory:
dP=ne T c dt=-d If there is re-ionization at a given redshift zre, photons are
diffuse there is a suppression of fluctuations on scales smaller than the horizon scale at zre (warning: degeneracy with spectral index n). The higher is zre, the smaller is the angular scale involved by diffusion.
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Power Spectra and Cosmological Parameters
Varying the baryonic density
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Power Spectra and Cosmological Parameters
Varying the Hubble constant
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Power Spectra and Cosmological Parameters
Varying the matter density
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Power Spectra and Cosmological Parameters
Varying the total density
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CMB Polarisation
• CMB photons have last been Thomson scattered
• directional dependence of Thomson cross section imprints polarisation
• polarisation pattern has similar, but shifted power spectrum
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Polarisation and Reionisation
• Universe recombined when CMB formed
• hydrogen was later reionised
• ionised hydrogen damps primordial fluctuations
• creates secondary polarisation
• constraints on reionisation from temperature-polarisation and polarisation power spectra
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Where were we?
WMAP 1st year results (Feb.03): TT & TE
EE detection by DASI (02), CBI (04), CAPMAP (05), Boomerang (05)
2dF: Percival et al. (02), Cole et al. (05).
CMB anisotropies
Galaxy surveys
SDSS: Tegmark et al. (04), Seljak et al. (05).
Ly used heavily in WMAP1, but not in WMAP3: “… further study is needed if the new values are consistent with
Ly data.” See however Viel et al. (06), Seljak et al. (06) for WMAP3 + Ly
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Issues after WMAP 1st year
Low amplitude for low multipoles of the Cl pattern
Weird alignment of the l=2,3 of alm
Sticky points out of the CDM fit
High value for
Evidence of running of the spectral index ?
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Will these “waves” in 1st year data persist?
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Temperature WMAP3 plus small scale CMB data
The spectrum is cosmic variance limited to l=400
(354 1st year)and S/N>1 up to l=850 (658 1st year)
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Red: WMAP1Black: WMAP3
Points: ratio of WMAP3 over WMAP1 value
Red line: ratio of window function WMAP1 over WMAP3
Red: WMAP1 with 06 analysis and 06 windows function
Black: WMAP3
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WMAP1 WMAP3
Anomaly on the octupole alleviated; quadrupole remains low
TE in better agreement with CDM; is almost half of 1st yr value
Some (but not all) of the sticky points remain
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Lines:Red: WMAP1
Orange: WMAP1 + CBI +ACBARBlack: WMAP3
Points:Grey: WMAP1Black: WMAP3
Bologna, 27 Aprile 2006courtesy from Spergel et al., 2006
CDM plus constraints
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courtesy from Hinshaw et al., 2006
CDM plus is a good fit to WMAP
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Polarization only useful for measuring tau for near future
Polarization probably best way to detect tensors
CMB Polarization
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Cosmological Parameters: Main WMAP3 parameter results rely on polarization
courtesy from A. Lewis, 2006
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WMAP3 TT with tau = 0.10 ± 0.03 prior (equiv to WMAP EE)
Black: TT+priorRed: full WMAP
courtesy from A. Lewis, 2006
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Implications for Nucleosynthesis
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courtesy from Page et al., 2006
From =0.170.04 (1st year)
To=0.090.03 (3 years)
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1 e 2 contours:Light Blue: WMAP1
Red: WMAP1 + CBI +ACBARBlue: WMAP3
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ns < 1or tau is highor there are tensorsor the model is wrongor we are quite unlucky
ns =1 So:
Is Harrison-Zeldovich Ruled out?
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Dark Energy: wDE≠ w = -1 for CMB anisotropies we needDE perturbations
wDE constant in time
cDE =1
(pDE=c2DE DE+…).
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WMAP 3 years results without DE perturbations are flawed
Effect known since Caldwell,Dave, Steinhardt PRL 1998
Abramo, Finelli, Pereira PRD 2004
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Massive Neutrinos
courtesy from Spergel et al., 2006
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Curvature K≠0
courtesy from Spergel et al., 2006
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Curvature K≠0 plus Dark Energy
courtesy from Spergel et al., 2006
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Gravity Waves
Baldi,Finelli,Matarrese, PRD72 (2005)
r0.002 < 0.55 (2) WMAP3 only
r0.002 < 0.28 (2) WMAP3 plus SDSS
rk* = PT(k*)/PS(k*)
r0.002 < 1.28 (2) WMAP1 only
r0.002 < 1.14 (2) WMAP1 plus 2dFGRS
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LCDM+Tensors No evidence from tensor modes
-is not going to get much betterfrom TT!
courtesy from A. Lewis, 2006
Finelli et al., in preparation (2006) Leach & Liddle, PRD (2003)
Single standard scalar field inflation: r = - 8 nT
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Black: SZ marge; Red: no SZ Slightly LOWERS ns
SZ Marginalization
Spergel et al.
WMAP-3 yr twist: SZ
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CMB lensing and WMAP3
Black: withred: without
- increases ns
not included in Spergel et al analysisopposite effect to SZ marginalization
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And Planck?
• to be launched in 2008
• improved frequency coverage (30-857 GHz) for improved foreground subtraction
• improved resolution (>5') and sensitivity (~µK)
• more accurate polarisation measurement
• foregrounds!
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Planck vs WMAP:1
courtesy from C. Burigana
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Planck vs WMAP:2
courtesy from C. Burigana
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Planck vs WMAP:3
courtesy from Planck Bluebook, astro-ph/0604069
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Planck vs WMAP:4
courtesy from Spergel et al., 2006
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courtesy from Planck Bluebook, astro-ph/0604069
Planck vs WMAP:5