151 research outputs found
Catholics & Cultures as an Act of Improvisation: A Response
This essay responds to seven articles published in the same issue of the Journal of Global Catholicism on the use of Catholics & Cultures, a multimedia website, as a pedagogical resource for college classrooms. The site is deliberately presented in a fashion that undermines notions of center and periphery and presents Catholicism from a lay, lived-religion perspective as the multicultural faith that it is, minimizing reference to religious typologies. Particular attention is given to how to navigate tensions around theorizing, categorizing and sorting information for cross-cultural comparison. Given scholars’ current state of knowledge, writing about and teaching about global Catholicism requires willingness to grapple with material that is inevitably new to us, and that we can only improvisationally categorize and theorize about
Clustering of Photometric Luminous Red Galaxies II: Cosmological Implications from the Baryon Acoustic Scale
A new determination of the sound horizon scale in angular coordinates is
presented. It makes use of ~ 0.6 x 10^6 Luminous Red Galaxies, selected from
the Sloan Digital Sky Survey imaging data, with photometric redshifts. The
analysis covers a redshift interval that goes from z=0.5 to z=0.6. We find
evidence of the Baryon Acoustic Oscillations (BAO) signal at the ~ 2.3 sigma
confidence level, with a value of theta_{BAO} (z=0.55) = (3.90 \pm 0.38)
degrees, including systematic errors. To our understanding, this is the first
direct measurement of the angular BAO scale in the galaxy distribution, and it
is in agreement with previous BAO measurements. We also show how radial
determinations of the BAO scale can break the degeneracy in the measurement of
cosmological parameters when they are combined with BAO angular measurements.
The result is also in good agreement with the WMAP7 best-fit cosmology. We
obtain a value of w_0 = -1.03 \pm 0.16 for the equation of state parameter of
the dark energy, Omega_M = 0.26 \pm 0.04 for the matter density, when the other
parameters are fixed. We have also tested the sensitivity of current BAO
measurements to a time varying dark energy equation of state, finding w_a =
0.06 \pm 0.22 if we fix all the other parameters to the WMAP7 best-fit
cosmology.Comment: 7 pages, 7 figures, Accepted for publication to MNRA
Clustering of photometric luminous red galaxies I : Growth of Structure and Baryon Acoustic Feature
The possibility of measuring redshift space (RSD) distortions using
photometric data have been recently highlighted. This effect complements and
significantly alters the detectability of baryon acoustic oscillations (BAO) in
photometric surveys. In this paper we present measurements of the angular
correlation function of luminous red galaxies (LRGs) in the photometric catalog
of the final data release (DR7) of the Sloan Digital Sky Survey II (SDSS). The
sample compromise ~ 1.5 x 10^6 LRGs distributed in 0.45 < z < 0.65, with a
characteristic photometric error of ~ 0.05. Our measured correlation centered
at z=0.55 is in very good agreement with predictions from standard LCDM in a
broad range of angular scales, . We find that the
growth of structure can indeed be robustly measured, with errors matching
expectations. The velocity growth rate is recovered as when no prior is imposed on the growth factor and the background geometry
follows a LCDM model with WMAP7+SNIa priors. This is compatible with the
corresponding General Relativity (GR) prediction for our
fiducial cosmology. If we adopt a parametrization such that , with in GR, and combine our
measurement with the corresponding ones from spectroscopic LRGs at lower
redshifts we obtain . In addition we find evidence for
the presence of the baryon acoustic feature matching the amplitude, location
and shape of LCDM predictions. The photometric BAO feature is detected with 98
% confidence level at z=0.55.Comment: 16 pages, 19 figures, minor changes to text to match accepted version
by MNRA
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The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the large-scale two-point correlation function
We obtain constraints on cosmological parameters from the spherically
averaged redshift-space correlation function of the CMASS Data Release 9 (DR9)
sample of the Baryonic Oscillation Spectroscopic Survey (BOSS). We combine this
information with additional data from recent CMB, SN and BAO measurements. Our
results show no significant evidence of deviations from the standard
flat-Lambda CDM model, whose basic parameters can be specified by Omega_m =
0.285 +- 0.009, 100 Omega_b = 4.59 +- 0.09, n_s = 0.96 +- 0.009, H_0 = 69.4 +-
0.8 km/s/Mpc and sigma_8 = 0.80 +- 0.02. The CMB+CMASS combination sets tight
constraints on the curvature of the Universe, with Omega_k = -0.0043 +- 0.0049,
and the tensor-to-scalar amplitude ratio, for which we find r < 0.16 at the 95
per cent confidence level (CL). These data show a clear signature of a
deviation from scale-invariance also in the presence of tensor modes, with n_s
<1 at the 99.7 per cent CL. We derive constraints on the fraction of massive
neutrinos of f_nu < 0.049 (95 per cent CL), implying a limit of sum m_nu < 0.51
eV. We find no signature of a deviation from a cosmological constant from the
combination of all datasets, with a constraint of w_DE = -1.033 +- 0.073 when
this parameter is assumed time-independent, and no evidence of a departure from
this value when it is allowed to evolve as w_DE(a) = w_0 + w_a (1 - a). The
achieved accuracy on our cosmological constraints is a clear demonstration of
the constraining power of current cosmological observations.Comment: 26 pages, 15 figures. Minor changes to match version accepted by
MNRA
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