2,235 research outputs found

    Cross-correlating the Microwave Sky with Galaxy Surveys

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    We present results for the cross-correlation between the WMAP 1st-year cosmic microwave background (CMB) anisotropy data and optical galaxy surveys: the APM and SDSS DR1 catalogs. Our measurement of a positive CMB-galaxy correlation on large angles (\theta > 4 deg) yields significant detections of the Integrated Sachs-Wolfe (ISW) effect and provides a new estimate of dark-energy in the universe, \Omega_\Lambda=0.69-0.86 (2 \sigma range). In addition, the correlated signal on small angles (\theta<1 deg) reveals the imprint left by hot intra-cluster gas in the CMB photons: the thermal Sunyaev-Zeldovich (SZ) effectComment: 7 pages. Invited talk at XVth Rencontres de Blois (France): "Physical Cosmology", June 2003. References adde

    Polarimetry in the Visible and Infrared: Application to CMB Polarimetry

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    Interstellar polarization from aligned dust grains can be measured both in transmission at visible and near-infrared wavelengths and in emission at far-infrared and sub-mm wavelengths. These observations can help predict the behavior of foreground contamination of CMB polarimetry by dust in the Milky Way. Fractional polarization in emission from aligned dust grains will be at the higher range of currently observed values of 4-10%. Away from the galactic plane, fluctuations in Q and U will be dominated by fluctuations in intensity, and less influenced by fluctuations in fractional polarization and position angle.Comment: To be published in the proceedings of "The Cosmic Microwave Background and its Polarization", New Astronomy Reviews, (eds. S. Hanany and K.A. Olive

    The Angular Power Spectrum of the First-Year WMAP Data Reanalysed

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    We measure the angular power spectrum of the WMAP first-year temperature anisotropy maps. We use SpICE (Spatially Inhomogeneous Correlation Estimator) to estimate Cl's for multipoles l=2-900 from all possible cross-correlation channels. Except for the map-making stage, our measurements provide an independent analysis of that by Hinshaw etal (2003). Despite the different methods used, there is virtually no difference between the two measurements for l < 700 ; the highest l's are still compatible within 1-sigma errors. We use a novel intra-bin variance method to constrain Cl errors in a model independent way. When applied to WMAP data, the intra-bin variance estimator yields diagonal errors 10% larger than those reported by the WMAP team for 100 < l < 450. This translates into a 2.4 sigma detection of systematics since no difference is expected between the SpICE and the WMAP team estimator window functions in this multipole range. With our measurement of the Cl's and errors, we get chi^2/d.o.f. = 1.042 for a best-fit LCDM model, which has a 14% probability, whereas the WMAP team obtained chi^2/d.o.f. = 1.066, which has a 5% probability. We assess the impact of our results on cosmological parameters using Markov Chain Monte Carlo simulations. From WMAP data alone, assuming spatially flat power law LCDM models, we obtain the reionization optical depth tau = 0.145 +/- 0.067, spectral index n_s = 0.99 +/- 0.04, Hubble constant h = 0.67 +/- 0.05, baryon density Omega_b h^2 = 0.0218 +/- 0.0014, cold dark matter density Omega_{cdm} h^2 = 0.122 +/- 0.018, and sigma_8 = 0.92 +/- 0.12, consistent with a reionization redshift z_{re} = 16 +/- 5 (68% CL).Comment: Matches version accepted by ApJ Letters. Main changes: emphasizes chi2 value for best-fit model given our estimate of Cls and errors vs. WMAP team's. Potential detection of systematics in WMAP data quantified. Power spectrum and other data files available at http://www.ifa.hawaii.edu/cosmowave/wmap.htm

    Anotaciones al margen de Don Lope de Cardona de Lope de Vega, posible comedia genealógica de encargo : raíces histórico-políticas

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    Se analiza Don Lope de Cardona de Lope de Vega como más que probable comedia genealógica de encargo; se desbrozan las raíces históricas de los caracteres principales y se sitúa la obra en el contexto político inmediato a su fecha de composición.In this study, Lope de Vega's Don Lope de Cardona is examined as almost certainly a genealogical play that was made to order; the historical roots of the main characters are clarified, and the work is placed within the political context of the time it was written
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