Browsing by Autor "Sergio Torres"

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A Method to Estimate the Primordial Power Spectrum from Cosmic Microwave Background Data
(IOP Publishing, 1996) Rafael Bautista; Sergio Torres
A precise determination of the primordial spectrum of matter density fluctuations at superhorizon scales is essential to understanding large-scale structure in the universe. Attempts to constrain or obtain the primordial spectrum using data on cosmic microwave background (CMB) anisotropies have relied on statistical and correlation analyses that assume a power-law spectrum. We propose a method to derive P(k) directly from the CMB angular power spectrum that does not presuppose the need to know anything about its functional form. The method consists of a direct inversion of the Sachs-Wolfe formula. Using this new analysis technique and COBE data, we obtain an empirical P(k) that (1) supports a power-law parameterization and (2) has an amplitude and spectral index consistent with previous analyses of the same data. We obtain for the spectral index n = 1.52±0.4 when the second-year COBE data are used and n = 1.22±0.3 using the 4 year data set.
Mapping the absolute brightness of the sky at low frequencies
(American Institute of Physics, 1992) Giovanni De Amici; G. F. Smoot; M. Bensadoun; M. Limon; W. Vinje; C. Witebsky; Sergio Torres; Antonio José Mejía Umaña; Miguel Velázquez de la Rosa Becerra
Uncertainties in the gain and zero‐level of the existing radio and microwave frequency sky surveys often dominate the error budget in studies of anisotropies and spectral distortions of the Cosmic Background Radiation.This paper discusses our existing prototype and the planned instruments and the observation techniques which are necessary for conducting an extended observational campaign to map the total sky brightness. Some experimental difficulties are outlined, and possible solutions are given.