Nearby Supernova Factory: Étalonnage des données de SNIFS et ...

tel-00372504, version 1 - 1 Apr 2009
CHAPTER 2. OBSERVATIONAL COSMOLOGY
By analyzing the anisotropies map (Fig. 2.1a), one can extract the fundamental oscillatory
mode and corresponding harmonics, and obtain its power spectrum (Fig. 2.1b). The exact form
of the peaks of the power spectrum depends on the matter content of the universe, thus the
measurement of its shape (a standard ruler), yields precise information about many cosmological
parameters. These measurements, while not probing dark energy directly, provide constraints
like the flatness (Ωk), or the baryon (Ωb) and dark matter densities (Ωc), that can be used to
infer ΩΛ.
(a) (b)
Figure 2.1: (a) WMAP 5 year CMB temperature anisotropies map from Hinshaw et al. (2008); (b) CMB
temperature power spectrum from the WMAP 5 year dataset (Nolta et al. 2008), along with results from
ACBAR (Reichardt et al. 2008), BOOMERANG (Jones et al. 2006) and CBI (Readhead et al. 2004).
The red curve is the best-fit ΛCDM model to the WMAP data.
The most recent CMB measurements come from the WMAP satellite (Komatsu et al. 2008),
whose 5 year results for a few ΛCDM parameters, combined with BAO (§ 2.2) and SNe (§ 2.3)
data, are expressed in Table 2.1. In the near future, a new generation of ground and space (like
the Planck satellite (The Planck Collaboration 2006)) experiments will further study the CMB
with even higher accuracy, searching e.g. for the imprint of primordial gravitational waves in
its polarization power spectrum.
Parameter WMAP+BAO+SN
t0 13.73 ± 0.12
H0 70.1 ± 1.3
Ωb 0.0462 ± 0.0015
Ωc 0.233 ± 0.013
ΩΛ 0.721 ± 0.015
1.0052 ± 0.0064
Ω0
Table 2.1: Some ΛCDM parameters inferred from the 5 year WMAP+BAO+SN. From Komatsu et al.
(2008).
2.2 Large Scale Structure
The various forms of structures (stars, galaxies, clusters of galaxies) we observe today in the
universe (Fig. 2.2), are collectively referred to as the large-scale structure (LSS). They are the
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