2,690 research outputs found
Cross-correlation of the CMB and radio galaxies in real, harmonic and wavelet spaces: detection of the integrated Sachs-Wolfe effect and dark energy constraints
We report the first detection of the ISW effect in wavelet space, at scales
in the sky around 7 degrees with a significance of around 3.3 sigma, by
cross-correlating the WMAP first-year data and the NRAO VLA Sky Survey (NVSS).
In addition, we present a detailed comparison among the capabilities of three
different techniques for two different objectives: to detect the ISW and to put
constraints in the nature of the dark energy. The three studied techniques are:
the cross-angular power spectrum (CAPS, harmonic space), the correlation
function (CCF, real space) and the covariance of the Spherical Mexican Hat
Wavelet (SMHW) coefficients (CSMHW, wavelet space). We prove that the CSMHW is
expected to provide a higher detection of the ISW effect for a certain scale.
This prediction has been corroborated by the analysis of the data. The SMHW
analysis shows that the cross-correlation signal is caused neither by
systematic effects nor foreground contamination. However, by taking into
account the information encoded in all the multipoles/scales/angles, the CAPS
provides slightly better constraints than the SMHW in the cosmological
parameters that define the nature of the dark energy. The limits provided by
the CCF are wider than for the other two methods. Two different cases have been
studied: 1) a flat Lambda-CDM universe and 2) a flat universe with an equation
of state parameter different from -1. In the first case, the CAPS provides (for
a bias value of b = 1.6) 0.59 < Lambda density < 0.84 (at 1 sigma CL).
Moreover, the CAPS rejects the range Lambda density < 0.1 at 3.5 sigma, which
is the highest detection of the dark energy reported up to date. In the second
case, the CAPS gives 0.50 < dark energy density < 0.82 and -1.16 < w < 0.43 (at
1 sigma CL).Comment: 12 pages, 7 figures, accepted for publication in MNRAS. Analysis
redone. Changes in the estimation of the cosmological parametres. Additional
comparison between wavelets and more standard technique
Error analysis in cross-correlation of sky maps: application to the ISW detection
Constraining cosmological parameters from measurements of the Integrated
Sachs-Wolfe effect requires developing robust and accurate methods for
computing statistical errors in the cross-correlation between maps. This paper
presents a detailed comparison of such error estimation applied to the case of
cross-correlation of Cosmic Microwave Background (CMB) and large-scale
structure data. We compare theoretical models for error estimation with
montecarlo simulations where both the galaxy and the CMB maps vary around a
fiducial auto-correlation and cross-correlation model which agrees well with
the current concordance LCDM cosmology. Our analysis compares estimators both
in harmonic and configuration (or real) space, quantifies the accuracy of the
error analysis and discuss the impact of partial sky survey area and the choice
of input fiducial model on dark-energy constraints. We show that purely
analytic approaches yield accurate errors even in surveys that cover only 10%
of the sky and that parameter constraints strongly depend on the fiducial model
employed. Alternatively, we discuss the advantages and limitations of error
estimators that can be directly applied to data. In particular, we show that
errors and covariances from the Jack-Knife method agree well with the
theoretical approaches and simulations. We also introduce a novel method in
real space that is computationally efficient and can be applied to real data
and realistic survey geometries. Finally, we present a number of new findings
and prescriptions that can be useful for analysis of real data and forecasts,
and present a critical summary of the analyses done to date.Comment: submitted to MNRAS, 26 page
Nomenclature for naming loci, alleles, linkage groups and chromosomes to be used in poultry genome publications and databases
International audienc
Photoproduction of Quarkonium in Proton-Proton and Nucleus-Nucleus Collisions
We discuss the photoproduction of and at high energy
, and heavy ion colliders. We predict large rates in
interactions at the Fermilab Tevatron %and in heavy-ion interactions at the
CERN LHC. These reactions can be and in and heavy-ion interactions at the
CERN LHC. The is also produced copiously at RHIC. These reactions can
be used to study the gluon distribution in protons and heavy nuclei. We also
show that the different CP symmetries of the initial states lead to large
differences in the transverse momentum spectra of mesonsComment: 4 pgs. with 3 figure
Predicting Patriarchy: Using Individual and Contextual Factors to Examine Patriarchal Endorsement in Communities
In much feminist literature, patriarchy has often been studied as a predictive variable for attitudes toward or acts of violence against women. However, rarely has patriarchy been examined as an outcome across studies. The current study works toward filling this gap by examining several individual-and neighborhood-level factors that might influence patriarchy. Specifically, this research seeks to determine if neighborhood-level attributes related to socioeconomic status, family composition, and demographic information affect patriarchal views after individual-level correlates of patriarchy were controlled. Findings suggest that factors at both the individual- and neighborhood levels, particularly familial characteristics and dynamics, do influence the endorsement of patriarchal views
Computation and interpretation of molecular Omega intracules
The Omega intracule is a three-dimensional function that describes the relative positions, momenta, and directions of motion of pairs of electrons in a system. In this paper, we describe the computation of the Omega intracule for a molecular system whose electronic wave function is expanded in a Gaussian basis set. This is followed by implementation details and numerical tests. Finally, we use the Omega intracules of a number of small systems to illustrate the power of this function to extract simple physical insights from complicated wave functions.We thank the ANU and ARC Grant
Nos. DP0664466 and DP0771978 for funding
Detection of the ISW effect and corresponding dark energy constraints made with directional spherical wavelets
Using a directional spherical wavelet analysis we detect the integrated
Sachs-Wolfe (ISW) effect, indicated by a positive correlation between the
first-year Wilkinson Microwave Anisotropy Probe (WMAP) and NRAO VLA Sky Survey
(NVSS) data. Detections are made using both a directional extension of the
spherical Mexican hat wavelet and the spherical butterfly wavelet. We examine
the possibility of foreground contamination and systematics in the WMAP data
and conclude that these factors are not responsible for the signal that we
detect. The wavelet analysis inherently enables us to localise on the sky those
regions that contribute most strongly to the correlation. On removing these
localised regions the correlation that we detect is reduced in significance, as
expected, but it is not eliminated, suggesting that these regions are not the
sole source of correlation between the data. This finding is consistent with
predictions made using the ISW effect, where one would expect weak correlations
over the entire sky. In a flat universe the detection of the ISW effect
provides direct and independent evidence for dark energy. We use our detection
to constrain dark energy parameters by deriving a theoretical prediction for
the directional wavelet covariance statistic for a given cosmological model.
Comparing these predictions with the data we place constraints on the
equation-of-state parameter and the vacuum energy density .
We also consider the case of a pure cosmological constant, i.e. . For
this case we rule out a zero cosmological constant at greater than the 99.9%
significance level. All parameter estimates that we obtain are consistent with
the standand cosmological concordance model values.Comment: 16 pages, 13 figures; replaced to match version accepted by MNRA
Signature of Gravity Waves in Polarization of the Microwave Background
Using spin-weighted decomposition of polarization in the Cosmic Microwave
Background (CMB) we show that a particular combination of Stokes and
parameters vanishes for primordial fluctuations generated by scalar modes, but
does not for those generated by primordial gravity waves. Because of this
gravity wave detection is not limited by cosmic variance as in the case of
temperature fluctuations. We present the exact expressions for various
polarization power spectra, which are valid on any scale. Numerical evaluation
in inflation-based models shows that the expected signal is of the order of 0.5
, which could be directly tested in future CMB experiments.Comment: 4 pages, 1 figure, RevTeX, matches the accepted version (to appear in
Phys. Rev. Lett.); code available at
http://arcturus.mit.edu:80/~matiasz/CMBFAST/cmbfast.htm
Recruitment of the default mode network during a demanding act of executive control.
In the human brain, a default mode or task-negative network shows reduced activity during many cognitive tasks and is often associated with internally-directed processes, such as mind wandering and thoughts about the self. In contrast to this task-negative pattern, we show increased activity during a large and demanding switch in task set. Furthermore, we employ multivoxel pattern analysis and find that regions of interest within default mode network are encoding task-relevant information during task performance. Activity in this network may be driven by major revisions of cognitive context, whether internally or externally focused
The Low Redshift survey at Calar Alto (LoRCA)
The Baryon Acoustic Oscillation (BAO) feature in the power spectrum of
galaxies provides a standard ruler to measure the accelerated expansion of the
Universe. To extract all available information about dark energy, it is
necessary to measure a standard ruler in the local, z<0.2, universe where dark
energy dominates most the energy density of the Universe. Though the volume
available in the local universe is limited, it is just big enough to measure
accurately the long 100 Mpc/h wave-mode of the BAO. Using cosmological N-body
simulations and approximate methods based on Lagrangian perturbation theory, we
construct a suite of a thousand light-cones to evaluate the precision at which
one can measure the BAO standard ruler in the local universe. We find that
using the most massive galaxies on the full sky (34,000 sq. deg.), i.e. a
K(2MASS)<14 magnitude-limited sample, one can measure the BAO scale up to a
precision of 4\% and 1.2\% using reconstruction). We also find that such a
survey would help to detect the dynamics of dark energy.Therefore, we propose a
3-year long observational project, named the Low Redshift survey at Calar Alto
(LoRCA), to observe spectroscopically about 200,000 galaxies in the northern
sky to contribute to the construction of aforementioned galaxy sample. The
suite of light-cones is made available to the public.Comment: 15 pages. Accepted in MNRAS. Please visit our website:
http://lorca-survey.ft.uam.es
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