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waynehu

Professor, Department of Astronomy and Astrophysics
University of Chicago

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CMB Introduction '96   Intermediate '01   Polarization Intro '01   Cosmic Symphony '04   Polarization Primer '97   Review '02   Power Animations   Lensing   Power Prehistory   Legacy Material '96   PhD Thesis '95 Baryon Acoustic Oscillations Cosmic Shear Clusters
Transfer Function WMAP Likelihood Reionization PPF for CAMB Halo Mass Conversion Cluster Abundance
Cosmology I [legacy 321] Cosmology II [321] Current Topics [282] Galaxies and Universe [242] Radiative Processes [305] Research Preparation [307] GR Perturbation Theory [408] CMB [448] Cosmic Acceleration [449]

Sensitivity

CMB anisotropy experiments currently in the planning stage should be able to reach the required angular resolution, sensitivity, sky coverage and reduction of systematic effects to probe the acoustic features in the spectrum. These include ground, long-duration balloon, and in particular two satellite experiments.

Figure: Sensitivity of the MAP satellite

With this kind of sensitivity, most of the cosmological parameters of a near-scale invariant adiabatic model can be fit to the several percent level (see e.g. Jungman et al. 1995, especially this figure). Assumptions about the underlying model may be relaxed as information in the higher peaks is uncovered to provide more of a true measurement of the parameters.

Figure: Sensitivity of the Planck Satellite (5.5 uK noise on 10'x10' pixels).

Whether these goals can actually be achieved depends on the level of foreground contamination (see e.g. Tegmark & Efstathiou (1995) especially this figure) and systematic effects. Galactic foregrounds will limit the area of clean sky available, increasing the error bars as the inverse square root of the fraction of sky, and foreground subtraction will increase the noise. Systematic effects (sidelobes, calibration, striping in the map from 1/f noise, etc.) may also degrade the sensitivity.

We are also here assuming that uncertain secondary anisotropies such as non-linear effects from reionization and gravitational lensing create only a small perturbation to the primary spectrum. This may not be a good assumption beyond l = 1000 .