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The Cosmic Microwave BackgroundPowerPoint Presentation

The Cosmic Microwave Background

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Brief History of time

Properties: isotropy and anisotropies

- The CMB radiation is isotropic
- We are moving with respect to the CMB rest frame
- There are tiny anisotropies, imprints of matter-radiation fluctuations.

Space Missions

- PLANCK:
- Smaller beam
- Lower noise
- Polarization
- Better frequency coverage

Measuring the Fundamental Properties of the Universe

Radiation

Matter

SDSS slice

CMB - Cosmic Microwave Background

(Temperature and Polarization)

DT(q,f) = S al,m Yl,m (q,f)

cl = Sm |al,m|2

d (x) = dr/r (x)

d (k) = FT[d (x)]

P(k) = < |d (k)|2>

Pgal(k) = b2 P(k)

bias

The power spectrum

Nolta et al 08

The decomposition of the CMB spectrum

Challinor 04

Evolution of fluctuations

Ma & Bertschinger 95

Line of sight approach

Seljak & Zaldarriaga 06

Polarization

Due to parity symmetry of the density field, scalar perturbations

Have U=0, and hence only produce E modes.

Scattering and polarization

If there is no U mode to start with, scattering does not generate it. No B mode is generated.

Scattering sources polarization through the quadrupole.

Tensor modes

Parity and rotation symmetry are no longer satisfied.

B modes could be generated, along with T and E.

The tensor modes expansion

Scattering only produces E modes, B

Are produced through coupling with E

And free streaming.

Power spectra for scalar and tensor perturbations

Tensor to scalar ratio r=1

Effect of parameters

- Effect of various parameters on the T and P spectrum

Fluctuation on scale enters the horizon

Derelativization

Expan. factor a

Matter dominated

Radiation dominated

Neutrinos free-stream

heavy

Neutrinos do not free-stream

(I.e. behave like Cold Dark Matter)

light

Recombination

(T=0.25 eV)

1)Neutrino mass: Physical effectson fluctuations

on expansion

- change the expansion rate
- Change matter-radiation equivalence (but not recombination)

Matter dominated

Radiation dominated

Recombination

2) The relativistic energy density NnNn = (rrad - rg) / r1n

3

>3

- Effects:
- change the expansion rate
- Change matter-radiation equivalence (but not the radiation temperature, I.e. not recombination)

- Model for:
- neutrino asymmetry
- other relativistic particles
- Gravitational wave contribution
- (Smith, Pierpaoli, Kamionkowski 2006)

CONSTRAINTS:

Before WMAP: N <17

After WMAP:N< 6.6

(Pierpaoli MNRAS 2003)

Neutrino species

Bell, Pierpaoli, Sigurdson 06

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