2,235 research outputs found
Cross-correlating the Microwave Sky with Galaxy Surveys
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
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
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
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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