1. Measurements of Cosmological Parameters
Amedeo Balbi
Dipartimento di Fisica & INFN
Università di Roma “Tor Vergata”

2. Background Cosmology
Expanding universe, described by Friedmann equation:

3. Perturbations & Inflation
Inflation generates perturbations through amplification of quantum fluctuations. In the basic picture, they obey Gaussian statistics, with a Harrison-Zel’dovich power spectrum:

4. Parameters from the CMB

5. CMB Anisotropy

6. CMB Power Spectrum
Bennet et al. 2003

7. Total Density
The typical angular size of fluctuations on the CMB depends on the global geometry of the Universe ( 1st peak position)
The universe is flat

8. Hubble Constant
HST Key Project: use Cepheids to calibrate distance indicators (z~0)
Combining X-ray flux and SZ effect in clusters of galaxies (z~0.5)
CMB: conformal distance to the decoupling surface (z~1000)
Spergel et al. 2003

9. Cosmic Ages
Spergel et al. 2003

10. Baryon Abundance
CMB, ratio of acoustic peaks amplitude (Spergel et al. 2003):
Primordial abundance of deuterium + BBN (Fields & Sarkar, 2004):

11. Primordial Abundances
Fields & Sarkar, 2004

12. Matter Density Power spectrum from redshift surveys (e.g., 2dF, SDSS):
Clusters of galaxies (e.g., Chandra):

13. Something Missing!

14. Type Ia Supernovae

15. Cosmic Concordance 1
(CMB)
1/3
(LSS)
2/3
(SN)

16. Amplitude of fluctuations
Spergel et al. 2003

17. Inflation Universe is flat
Primordial perturbations are adiabatic, Gaussian and scale-invariant (spectral index near unity)
Gravitational wave background (tensor modes) is negligible
No viable alternative makes all these predictions

18. Problems with Lambda
Vacuum fluctuations in QFT:
“Why now?”:

19. Dark Energy? Ideal fluid with generic equation of state:
E.g., scalar field:

20. Constraints on Dark Energy
Seljak et al. 2004

21. Precision Cosmology