Bologna, 27 Aprile 2006 WMAP – 3-year results Fabio Finelli INAF/OAB & INAF/IASF-BO Lauro...

Bologna, 27 Aprile 2006

WMAP – 3-year results

Fabio Finelli

INAF/OAB & INAF/IASF-BO

Lauro Moscardini

Dip. Astronomia UniBo


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


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


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


Sky Maps

foregrounds:synchrotron,dust,free-freeemission


Temperature Map

• foreground subtraction: spectra differ from the CMB's Planck spectrum

• comparison of signals from different channels

• fitting of foreground templates


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


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


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


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


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


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.


Power Spectra and Cosmological Parameters

Varying the baryonic density



Varying the Hubble constant



Varying the matter density



Varying the total density


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


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


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


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 ?


Will these “waves” in 1st year data persist?


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)


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


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


Lines:Red: WMAP1

Orange: WMAP1 + CBI +ACBARBlack: WMAP3

Points:Grey: WMAP1Black: WMAP3

Bologna, 27 Aprile 2006courtesy from Spergel et al., 2006

CDM plus constraints


courtesy from Hinshaw et al., 2006

CDM plus is a good fit to WMAP


Polarization only useful for measuring tau for near future

Polarization probably best way to detect tensors

CMB Polarization


Cosmological Parameters: Main WMAP3 parameter results rely on polarization

courtesy from A. Lewis, 2006


WMAP3 TT with tau = 0.10 ± 0.03 prior (equiv to WMAP EE)

Black: TT+priorRed: full WMAP



Implications for Nucleosynthesis


courtesy from Page et al., 2006

From =0.170.04 (1st year)

To=0.090.03 (3 years)

Bologna, 27 Aprile 2006courtesy from Spergel et al., 2006

1 e 2 contours:Light Blue: WMAP1

Red: WMAP1 + CBI +ACBARBlue: WMAP3


ns < 1or tau is highor there are tensorsor the model is wrongor we are quite unlucky

ns =1 So:

Is Harrison-Zeldovich Ruled out?


Dark Energy: wDE≠ w = -1 for CMB anisotropies we needDE perturbations

wDE constant in time

cDE =1

(pDE=c2DE DE+…).


WMAP 3 years results without DE perturbations are flawed

Effect known since Caldwell,Dave, Steinhardt PRL 1998

Abramo, Finelli, Pereira PRD 2004


Massive Neutrinos

courtesy from Spergel et al., 2006


Curvature K≠0



Curvature K≠0 plus Dark Energy



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


LCDM+Tensors No evidence from tensor modes

-is not going to get much betterfrom TT!


Finelli et al., in preparation (2006) Leach & Liddle, PRD (2003)

Single standard scalar field inflation: r = - 8 nT


Black: SZ marge; Red: no SZ Slightly LOWERS ns

SZ Marginalization

Spergel et al.

WMAP-3 yr twist: SZ


CMB lensing and WMAP3

Black: withred: without

- increases ns

not included in Spergel et al analysisopposite effect to SZ marginalization


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!


Planck vs WMAP:1

courtesy from C. Burigana


Planck vs WMAP:2

courtesy from C. Burigana


Planck vs WMAP:3

courtesy from Planck Bluebook, astro-ph/0604069


Planck vs WMAP:4



courtesy from Planck Bluebook, astro-ph/0604069

Planck vs WMAP:5

Bologna, 27 Aprile 2006 WMAP – 3-year results Fabio Finelli INAF/OAB & INAF/IASF-BO Lauro...

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