CMB as a physics laboratory

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

Cosmic Dust Point sources Free free Synchrot. Tegmark, 2000

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.

Background CMB z = 1100

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’

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….

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

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

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 !

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

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

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)

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

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

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

Integrated Sachs-Wolfe effect .

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

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 !!

Acoustic oscillations LSS z = 0 z = 1100

Coupled fluctuations D. Eisenstein

Acoustic oscillations

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 !!

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 !!

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

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)

Weak Lensing in CMB Lensed temperature field Temperature field Hu 2002

How is polarization generated? Thomson Scattering

Density pert. & Gravity Waves Gravity Waves

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

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

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 !!

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 !!