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Motivations

Figure 1: Most accurate available results, taken by the COBE satellite, and the experiments Boomerang, Maxima, DASI. We note the lack of measurements between COBE and other experiments. Archeops'main goal is to link these data sets with one single measurement. Three different inflationnary models are also plotted, showing the influence of the cosmological paremeters on the power spectrum.
\includegraphics[height=3.5in]{cl_2001.ps}

After the extremely accurate CMB spectrum measurement by the COBE satellite in 1989, proving that the radiation was a perfect blackbody [6,7], and the first detection of deviations [5] from the perfect homogeneity at the level of 10$^{-5}$ K, most experiments have concentrated on improving the measurement of the anisotropies. In most theories and with consistent available data, the statistical distribution of the CMB anistropies is Gaussian. The anisotropies are therefore represented by their spherical harmonic power spectrum (non-Gaussianity is nevertheless looked for). The most accurate results are from COBE on large angular scale ($>$ 7 degrees) and on small angular scales ($<$ 2 degrees) from Boomerang [8], Maxima [9], and DASI [10] (see Figure 1). The intermediate angular scales, between COBE and the other experiments, lack measurements, due to the small sky coverage of these experiments. The main Archeops goal is to link COBE and Boomerang-Maxima-DASI angular scales, with high-sensitivity detectors covering a large fraction of sky (30% of the sky). Archeops is also a testbed for Planck-HFI, using the same type of cryogenic system and detectors; and it measures dust and galactic sources in a polarized frequency band.
next up previous
Next: Instrument and Scan-strategy Up: amblard_cosmo01 Previous: Introduction
F.-Xavier Desert LAOG 2001-12-10