249,115 research outputs found
Cross Sectional and Longitudinal Fuzzy Clustering of the NUTS and Positioning of the Italian Regions with Respect to the Regional Competitiveness Index (RCI) Indicators with Contiguity Constraints
In socio-economical clustering often the empirical information is represented by time-varying data generated by indicators observed over time on a set of subnational (regional) units. Usually among these units may exist contiguity relations, spatial but not only.In this paper we propose a fuzzy clustering model of multivariate time-varying data, the longitudinal fuzzy C-Medoids clustering with contiguity constraints. The temporal aspect is dealt with by using appropriate measures of dissimilarity between time trajectories. The contiguity among units is dealt with adding a contiguity matrix as a penalization term in the clustering model.The cross sectional fuzzy C-Medoids clustering with contiguity constraints is obtained considering one instant of time. The model is applied to the classification of the European NUTS on the basis of the observed dynamics of the Basic, Efficiency and Innovation subindexes of the Regional Competitiveness Index (RCI) 2013 and 2016. The positioning of the Italian regions is analyzed through the values of the medoids of the clusters and shows the peculiarities of the regions with respect to the subindexes either in single times or in the dynamic. Two contiguity constraints, one based on the European Western, Southern, Central and Northern geographic areas and one on the level of GDP—taken into account in the computation of the RCI—are also introduced in the models
The Asiago-ESO/RASS QSO Survey. III. Clustering analysis and its theoretical interpretation
This is the third paper of a series describing the Asiago-ESO/RASS QSO survey
(AERQS), a project aimed at the construction of an all-sky statistically
well-defined sample of relatively bright QSOs (B<15) at z<0.3. We present here
the clustering analysis of the full spectroscopically identified database (392
AGN). The clustering signal at 0.02<z<0.22 is detected at a 3-4 sigma level and
its amplitude is measured to be r_0=8.6\pm 2.0 h^{-1} Mpc (in a LambdaCDM
model). The comparison with other classes of objects shows that low-redshift
QSOs are clustered in a similar way to Radio Galaxies, EROs and early-type
galaxies in general, although with a marginally smaller amplitude. The
comparison with recent results from the 2QZ shows that the correlation function
of QSOs is constant in redshift or marginally increasing toward low redshift.
We discuss this behavior with physically motivated models, deriving interesting
constraints on the typical mass of the dark matter halos hosting QSOs, M_DMH=
10^{12.7} h^{-1} M_sun (10^{12.0}-10^{13.5}h^{-1} M_sun at 1 sigma confidence
level). Finally, we use the clustering data to infer the physical properties of
local AGN, obtaining M_BH=2 10^8 h^{-1} M_sun (10^7-3 10^9 h^{-1} M_sun) for
the mass of the active black holes, tau_{AGN}= 8 10^6 yr (2 10^{6}-5 10^{7} yr)
for their life-time and eta = 0.14 for their efficiency (always for a LambdaCDM
model).Comment: 37 pages, Astronomical Journal in press. Changes to match the referee
comment
Integrated approach to cosmology: Combining CMB, large-scale structure and weak lensing
Recent observational progress has led to the establishment of the standard
CDM model for cosmology. This development is based on different
cosmological probes that are usually combined through their likelihoods at the
latest stage in the analysis. We implement here an integrated scheme for
cosmological probes, which are combined in a common framework starting at the
map level. This treatment is necessary as the probes are generally derived from
overlapping maps and are thus not independent. It also allows for a thorough
test of the cosmological model and of systematics through the consistency of
different physical tracers. As a first application, we combine current
measurements of the Cosmic Microwave Background (CMB) from the Planck
satellite, and galaxy clustering and weak lensing from SDSS. We consider the
spherical harmonic power spectra of these probes including all six auto- and
cross-correlations along with the associated full Gaussian covariance matrix.
This provides an integrated treatment of different analyses usually performed
separately including CMB anisotropies, cosmic shear, galaxy clustering,
galaxy-galaxy lensing and the Integrated Sachs-Wolfe (ISW) effect with galaxy
and shear tracers. We derive constraints on CDM parameters that are
compatible with existing constraints and highlight tensions between data sets,
which become apparent in this integrated treatment. We discuss how this
approach provides a complete and powerful integrated framework for probe
combination and how it can be extended to include other tracers in the context
of current and future wide field cosmological surveys.Comment: 29 pages, 19 figures, 3 tables, to appear in PRD, updated following
referee's comments including small changes in result
Integrated cosmological probes: Concordance quantified
Assessing the consistency of parameter constraints derived from different
cosmological probes is an important way to test the validity of the underlying
cosmological model. In an earlier work [Nicola et al., 2017], we computed
constraints on cosmological parameters for CDM from an integrated
analysis of CMB temperature anisotropies and CMB lensing from Planck, galaxy
clustering and weak lensing from SDSS, weak lensing from DES SV as well as Type
Ia supernovae and Hubble parameter measurements. In this work, we extend this
analysis and quantify the concordance between the derived constraints and those
derived by the Planck Collaboration as well as WMAP9, SPT and ACT. As a measure
for consistency, we use the Surprise statistic [Seehars et al., 2014], which is
based on the relative entropy. In the framework of a flat CDM
cosmological model, we find all data sets to be consistent with one another at
a level of less than 1. We highlight that the relative entropy is
sensitive to inconsistencies in the models that are used in different parts of
the analysis. In particular, inconsistent assumptions for the neutrino mass
break its invariance on the parameter choice. When consistent model assumptions
are used, the data sets considered in this work all agree with each other and
CDM, without evidence for tensions.Comment: 17 pages, 4 figures, 2 tables, updated following referee's comments,
now includes discussion of the Riess et al., 2016 Hubble parameter
measurement, matches version accepted by JCA
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey : cosmological implications of the full shape of the clustering wedges in the data release 10 and 11 galaxy samples
We explore the cosmological implications of the angle-averaged correlation function, ξ(s), and the clustering wedges, ξ⊥(s) and ξ∥(s), of the LOWZ and CMASS galaxy samples from Data Releases 10 and 11 of the Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey. Our results show no significant evidence for a deviation from the standard Λ cold dark matter model. The combination of the information from our clustering measurements with recent data from the cosmic microwave background is sufficient to constrain the curvature of the Universe to Ωk = 0.0010 ± 0.0029, the total neutrino mass to ∑mν < 0.23 eV (95 per cent confidence level), the effective number of relativistic species to Neff = 3.31 ± 0.27 and the dark energy equation of state to wDE = −1.051 ± 0.076. These limits are further improved by adding information from Type Ia supernovae and baryon acoustic oscillations from other samples. In particular, this data set combination is completely consistent with a time-independent dark energy equation of state, in which case we find wDE = −1.024 ± 0.052. We explore the constraints on the growth rate of cosmic structures assuming f(z) = Ωm(z)γ and obtain γ = 0.69 ± 0.15, consistent with the predictions of general relativity of γ = 0.55.Publisher PDFPeer reviewe
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