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Published July 15, 1996 | Published
Journal Article Open

Cosmological-parameter determination with microwave background maps


The angular power spectrum of the cosmic microwave background (CMB) contains information on virtually all cosmological parameters of interest, including the geometry of the Universe (Ω), the baryon density, the Hubble constant (h), the cosmological constant (Λ), the number of light neutrinos, the ionization history, and the amplitudes and spectral indices of the primordial scalar and tensor perturbation spectra. We review the imprint of each parameter on the CMB. Assuming only that the primordial perturbations were adiabatic, we use a covariance-matrix approach to estimate the precision with which these parameters can be determined by a CMB temperature map as a function of the fraction of sky mapped, the level of pixel noise, and the angular resolution. For example, with no prior information about any of the cosmological parameters, a full-sky CMB map with 0.5° angular resolution and a noise level of 15 μK per pixel can determine Ω, h, and Λ with standard errors of ±0.1 or better, and provide determinations of other parameters which are inaccessible with traditional observations. Smaller beam sizes or prior information on some of the other parameters from other observations improves the sensitivity. The dependence on the underlying cosmological model is discussed.

Additional Information

© 1996 The American Physical Society Received 20 December 1995 We would like to thank Scott Dodelson, Lloyd Knox, Michael Turner, and members of the MAP Collaboration for helpful discussions, and George Smoot for useful comments. Martin White graciously provided Boltzmann-code power spectra for benchmarking our code. This work was supported in part by the (U.S.) DOE under Contracts No. DEFG02-92-ER 40699 at Columbia University and No. DEFG02-85-ER 40231 at Syracuse University, by the Harvard Society of Fellows, by the NSF under Contract No. ASC 93-18185 (GC3 collaboration) at Princeton University, by NASA under Contracts No. NAG5-3091 at Columbia University and No. NAGW-2448, and under the MAP Mission Concept Study Proposal at Princeton University. Portions of this work were completed at the Aspen Center for Physics.

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