1. CMB as a physics laboratory

2. Recombination Hydrogen is ionized Thomson Scattering
T = 0.3 eV << me c2
Hydrogen is ionized
Thomson Scattering
Hydrogen is neutral

3. Cosmic
Dust
Point sources
Free free
Synchrot.
Tegmark, 2000

4. Microwave Decoupling: photon mean free path, l=1/nesT > H-1.
Tdec=3000K depends essentially only on the baryon density (ne) and on the total matter density (H-1 ).
After 10Gyr, this has to cool by a factor of roughly 1000: the present black body spectrum at Tcmb=2.726K is then an immediate indication that the values of Wtot ,Wb H0 we currently use are in the right ballpark.

5. Background
CMB
z = 1100

6. History Prediction Tcmb DT/T grav. DT/T Thomson Polarization
1941
McKellar
CH,CN excitation temperature in stars
1949
Gamow
Prediction Tcmb
1964
Penzias Wilson
10-1
1966
Sachs Wolfe
DT/T grav.
1970
Peebles Yu
DT/T Thomson
1992
COBE
10-4 70
1999
Boomerang
10-5
20’
2002
DASI
Polarization
2003
WMap
18’
2007
Planck
10-6 7’

7. Is the Universe…. Ask the CMB…. Geometry Dynamics Initial conditions
Growth of fluctuations
Open, closed, flat, compact,
accelerated, decelerated,
initially gaussian, scale invariant,
adiabatic, isocurvature,
einsteinian…?
Ask the CMB….

8. What do we expect to find on the CMB?
Wo ,WL,W b ,n R,NR ,H0
ns, nt , s8
inflation pot. V (f)
the standard universe
XXXXX
boring
W f,wf,b
VEP
the unexpected universe
XXXXXXX
exciting
topological defects
bouncing universe
Compact topology
Extra dimensions
very exciting
XXXX
the weird
universe

9. Perturbing the CMB
Observable: radiation intensity per unit frequency per polarization state at each point in sky:
DT, D P, D E(n)
In a homogeneous universe, the CMB is the same perfect black-body in every direction
In a inhomogenous universe, the CMB can vary in:
intensity
Grav. Pot, Doppler, intrinsic fluctuations
D T
polarization
anisotropic scattering, grav. waves
D P
spectrum
energy injection z<106
D E

10. Predicting the CMB Complicate but linear !
General relativistic equations for baryons, dark matter, radiation, neutrinos,...
Solve the perturbed, relativistic, coupled, Boltzmann equation
Obtain the DT/T for all Fourier modes and at all times
Convert to the DT/T on a sphere at z=1100 around the observer
Complicate but linear !

11. Fluctuation spectrum From DT/T To Cl Large scales Small scales
Noater che la Cl e’ complicata, perche’ dipende da molti parametri cosmologici.
Complication==good; citare l’esistenza della scala fondamentale dell’orizzonte al disaccoppiamento
Large
scales
Small
scales

12. Temperature fluctuations
Archaic
(>horizon scale)
Middle Age
Contemporary
(<damping scale)
q > 20
l < 100
20 < q <10’
100 < l < 1000
q < 10’
l > 1000
z>>1000
1000>z>10
z<10

13. Archaic CMB
Sachs-Wolfe effect of superhorizon inflationary perturbations
Integrated Sachs-Wolfe effect of subhorizon fluctuations: when the gravitational potential is not constant (eg, nonflat metric, other components, non-linearity, etc)

14. Sachs-Wolfe effect
Last Scatt. Surface F
z = 0 SW
ISW
z = 1100 . F

15. Fluctuation spectrum
Noater che la Cl e’ complicata, perche’ dipende da molti parametri cosmologici.
Complication==good; citare l’esistenza della scala fondamentale dell’orizzonte al disaccoppiamento

16. Sachs-Wolfe effect P(k)=Akn Data: Cobe +Boomerang
Nota: ci sono due effetti: DT dovuto al delta rho_gamma (intrinseco) e DT dovuto al pot. Grav. (SW). Poiche’
Il pot grav e’ potenziato dal k^2 al denominatore, il SW vince a grandi scale (se HZ va come k^1, if not,
could be otherwise!).
Notare anche che senza inflazione SW=0
E che l’1/3 nel dt/t dipende dal time dilation at last scattering, che fa provenire la radiazione dentro una perturbazione positiva da un epoca leggermente anteriore e quindi piu’ calda
P(k)=Akn

17. Integrated Sachs-Wolfe effect.

18. Middle age CMB Acoustic perturbations:
perturbations oscillate acoustically when their size is smaller than the sound horizon (the pressure wave has the time to cross the structure)
The oscillations are coherent !
hear the sound of the universe
rather, we see the sound

19. The sound horizon at decoupling
The decoupling occurred 300,000 yrs after the big bang
Acoustic perturbations in the photon-baryon plasma travelled at the sound speed
Therefore they propagated for
(almost) independently of cosmology.
Spiegare perche’ e’ quasi indip. dalla cosmologia.
Calcolare 0.05X 1000/3000=1/60 rad=1 deg !!

20. Acoustic oscillations
LSS
z = 0
z = 1100

21. Coupled fluctuations
D. Eisenstein

22. Acoustic oscillations

23. First peak: Sound horizon
angular size : sensitive to the dominant components
amplitude : sensitive to the baryon component
le dimensioni fisiche del sound horizon dipendono dalla dinamica tra zero e decoupling;
le dim. angolari dipendono dalla distanza della LSS, e quindi dalla dinamica tra decoupling ed ora !!

24. Sound horizon
le dimensioni fisiche del sound horizon dipendono dalla dinamica tra zero e decoupling;
le dim. angolari dipendono dalla distanza della LSS, e quindi dalla dinamica tra decoupling ed ora !!

25. Acoustic peaks Data: Boomerang 1999
Late ISW (da Lambda) conta solo a grandi scale perche’ quelle piccole sono attraversate varie volte dai fotoni, e dunque i contributi di segno opposto sui pot. gravitazionali di picchi e valli si cancellano
Data: Boomerang 1999

26. Contemporary CMB Processes along the line-of-sight:
SZ effect: inverse Compton scattering (cluster masses)
stochastic lensing ( mass fluctuation power)
reionization ( epoch of first light)

27. Weak Lensing in CMB
Lensed temperature field
Temperature field
Hu 2002

28. How is polarization generated?
Thomson Scattering

29. Density pert.
&
Gravity Waves
Gravity
Waves

30. CMB in 1999…
…2001
…2003
con la precisione permessa dalla cmb

31. Sensitivity Hu, 2002 Now Map, 2003 Planck, 2007
In case you doubts about the sensitivity to detect the parameters
Planck, 2007

32. The geometric effect
le dimensioni fisiche del sound horizon dipendono dalla dinamica tra zero e decoupling;
le dim. angolari dipendono dalla distanza della LSS, e quindi dalla dinamica tra decoupling ed ora !!

33. The kinematic effect
le dimensioni fisiche del sound horizon dipendono dalla dinamica tra zero e decoupling;
le dim. angolari dipendono dalla distanza della LSS, e quindi dalla dinamica tra decoupling ed ora !!