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C.J. Miller, R.C. Nichol, C. Genovese, L Wasserman (CMU)
We examine Cosmic Microwave Background (CMB) temperature power spectra from the BOOMERANG, MAXIMA, and DASI experiments. We non-parametrically estimate the true power spectrum with no model assumptions. This is a significant departure from previous research which used either cosmological models or some other parameterized form (e.g. parabolic fits). Our non-parametric estimate is practically indistinguishable from the best fit cosmological model, thus lending independent support to the underlying physics that governs these models. We also generate a confidence set for the non-parametric fit and extract confidence intervals for the numbers, locations, and heights of peaks and the successive peak-to-peak height ratios. At the 95%, 68%, and 40% confidence levels, we find functions that fit the data with one, two, and three peaks respectively ( 0 <= l <= 1100). Therefore, the current data prefer two peaks at the 1 sigma level. If we assume that there are three peaks in the data, we find their locations to be within l1 = (118,300), l2 = (377,650), and l3 = (597,900). We find the ratio of the first peak-height to the second (dT1/dT2)2 = (1.06, 4.27) and the second to the third (dT2/dT3)2 = (0.41, 2.5). All measurements are for 95% confidence. If the standard errors on the temperature measurements were reduced to a third of what they are currently, as we expect to be achieved by the MAP and Planck CMB experiments, we could eliminate two-peak models at the 95% confidence limit. The non-parametric methodology discussed in this paper has many astrophysical applications.
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The author(s) of this abstract have provided an email address for comments about the abstract: chrism@cmu.edu