Precision cosmology, status and perspectives Alessandro Melchiorri Universita’ di Roma, “La Sapienza” INFN, Roma-1 FA-51 Meeting Frascati, June 22nd 2010

The Cosmic Microwave Background Discovered By Penzias and Wilson in It is an image of the universe at the time of recombination (near baryon-photons decoupling), when the universe was just a few thousand years old ( z~1000). The CMB frequency spectrum is a perfect blackbody at T=2.73 K: this is an outstanding confirmation of the hot big bang model.

Uniform... Dipole... Galaxy (z=0) The Microwave Sky COBE Imprint left by primordial tiny density inhomogeneities ( z~1000)..

WMAP

Larger scales

CMB Anisotropies Four mechanisms are responsable for CMB anisotropies: Gravity (Sachs-Wolfe effect) Intrinsic (Adiabatic) Fluctuations Doppler effect Time-Varying Potentials (Integrated Sachs-Wolfe Effect) Gravity Adiabatic Doppler ISW Visibility Function

Hu, Sugiyama, Silk, Nature 1997, astro-ph/

WMAP

Temperature Angular spectrum varies with  tot  b  c  h  n s, … We can measure cosmological parameters with CMB !

How to get a bound on a cosmological parameter DATA Fiducial cosmological model: ( Ω b h 2, Ω m h 2, h, n s, τ, Σ m ν ) PARAMETER ESTIMATES

Dunkley et al., 2008

Komatsu et al, 2010, New WMAP results from 7 years of observations

Improvement in constraining Inflationary Parameters from WMAP5 to WMAP7 Ruling out n=1 (HZ spectrum) would be a great success for inflation (primordial pertubations are produced by a dynamical mechanism).

HZ spectrum Inflation predicts but Inflation predicts but A major point to clarify is if HZ’s n=1 A major point to clarify is if HZ’s n=1 is ruled out from currrent observations or not. If this would provide an indication for the dynamical evolution of the expansion rate as perturbation are being produced If this would provide an indication for the dynamical evolution of the expansion rate as perturbation are being produced

For inflation produced by a single scalar field, during the slow- roll phase, the kinetic energy of the field is negligible and the potential is nearly constant: This gives rise to a (quasi-) de Sitter phase: The perturbations in the field are proportional to the value of the Hubble parameter at the time of horizon crossing: Since V(  ) is not actually constant, but slowly-varying, we expect a weak dependence of the amplitude of the perturbations on the wavenumber If the perturbations were originated from the dynamics of a scalar field the spectrum should not be exactly scale invariant

Sudden Reionization As we don’t know precisely the details of the reionization history we should consider more general reionization scenarios CAMB Notes, Antony Lewis

MH’s Reionization Following Mortonson & Hu we can parametrize the reionization history as a free function of the redshift by decomposing the free electron fraction as The principal components S  (z) are the eigenfunctions of the Fisher matrix of an ideal, cosmic variance limited, experiment. The principal components S  (z) are the eigenfunctions of the Fisher matrix of an ideal, cosmic variance limited, experiment. m  are the amplitudes of the S  (z) m  are the amplitudes of the S  (z) x(z) is the WMAP fiducial model at which the FM is computed x fid (z) is the WMAP fiducial model at which the FM is computed M. J. Mortonson and W. Hu ApJ 686, L53 (2008)

Caveat (example): Constraints on inflationary parameters depend on assumption of Sudden reionization scenario. A more general scheme based on principal components (Mortonson and Hu, MH) can put n=1 back in agreement with observations. Planck will settle the issue. Pandolfi, Cooray, Giusarma, Kolb, Melchiorri, Mena, Serra, Phys. Rev. D 81, (2010) WMAP7 +MH + Tensors (no tensor)

Pandolfi, Cooray, Giusarma, Kolb, Melchiorri, Mena, Serra, Phys. Rev. D 81, (2010)

Komatsu et al, 2010,

Small scale CMB can probe Helium abundance at recombination. Changes in the visibility function.

Komatsu et al, 2010,

CMB Anisotropies Four mechanisms are responsable for CMB anisotropies: Gravity (Sachs-Wolfe effect) Intrinsic (Adiabatic) Fluctuations Doppler effect Time-Varying Potentials (Integrated Sachs-Wolfe Effect) Gravity Adiabatic Doppler ISW Visibility Function

Hu, Sugiyama, Silk, Nature 1997, astro-ph/

Komatsu et al, 2010, Neutrino background. Changes early ISW. Hint for N>3 ?

Gianpiero ManganoGianpiero Mangano, Alessandro Melchiorri, Olga Mena, Gennaro Miele, Anze SlosarAlessandro MelchiorriOlga MenaGennaro MieleAnze Slosar Journal-ref: JCAP0703:006,2007

South Pole Telescope- SPT

Atacama Cosmology Telescope ACT

New small-scale CMB measurements by ACT and SPT Flowler et al (ACT collaboration), 2010

Thermal Sunyaev-Zel’dovich effect SPT sampling frequencies at 150 and 220 GHz can discriminate it from Dusty Star Forming Galaxies (DSFG) foregrounds (ACT can’t).

M. Lueker et al (SPT collaboration), 2009 Thermal SZ Kinetic SZ Unresolved Point Sources

SPT measures an SZ amplitude lower by a factor 2 than expected ! Systematics ? SZ model ? New physics ? (Dark coupling, modified GR, Dark Matter) ?

Planck Satellite launch 14/5/2009

Planck First Light Survey (September 2009). Experiment is working as expected

Blue: current data Red: Planck

When the luminous source is the CMB, the lensing effect essentially re-maps the temperature field according to : unlensed lensed Taken from (Max Planck Institute for Astronomy at Heidelberg )Max Planck Institute for Astronomy at Heidelberg CMB Temperature Lensing

Where the lensing potential power spectrum is given by : Lensing Effect on Temperature Power Spectrum We obtain a convolution between the lensing potential power spectrum and the unlensed anisotropies power spectrum: The net result is a 3% broadening of the CMB angular power spectrum acustic peaks

Lensing della CMB e esperimenti futuri

New Measurements, New Parameters ! Neutrino masses Neutrino effective number Primordial Helium Fundamental Constants

Galli, Martinelli, Melchiorri, Pagano, Sherwin, Spergel, PRD submitted, arXiv:

Galli, Martinelli, Melchiorri, Pagano, Sherwin, Spergel, PRD submitted, arXiv:

Galli, Martinelli, Melchiorri, Pagano, Sherwin, Spergel, to be submitted 2010

Galli, Martinelli, Melchiorri, Pagano, Sherwin, Spergel, PRD submitted, arXiv:

Recent CMB measurements fully confirm  -CDM. Improved constraints on inflation Ionization History still to be probed by observations. Problems with integrated SZ effect on small scales (now too low). With future measurements constraints on new parameters related to laboratory Physics could be achieved.