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Published February 12, 1996 | Published
Journal Article Open

Weighing the Universe with the Cosmic Microwave Background


Variations in Ω, the total density of the Universe, leave an imprint on the power spectrum of temperature fluctuations in the cosmic microwave background (CMB). We evaluate the precision with which Ω can be determined by a CMB map as a function of sky coverage, pixel noise, and beam size. Assuming only that the primordial density perturbations were adiabatic and with no prior information on the values of any other cosmological parameters, a full-sky CMB map at 0.5° angular resolution and a noise level of 15 μK per pixel can determine Ω with a standard error of 5%. If all other cosmological parameters are fixed, Ω can be measured to better than 1%.

Additional Information

© 1996 The American Physical Society Received 20 July 1995 We would like to thank Scott Dodelson, Lloyd Knox, Michael Turner, and members of the MAP Collaboration for helpful discussions. This work is supported in part by the 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, and by NASA under Contract No. NAGW-2448 and under the MAP Mission Concept Study Proposal at Princeton University. M.K. acknowledges the hospitality of the NASA/Fermilab Astrophysics Center where part of this work was completed.

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