Probing cosmic isotropy in the Local Universe

Abstract

This is a model-independent analysis that investigates the statistical isotropy in the Local Universe using the ALFALFA survey data ($0<z<0.06$). We investigate the angular distribution of HI extra-galactic sources from the ALFALFA catalogue and study whether they are compatible with the statistical isotropy hypothesis using the two-point angular correlation function (2PACF). Aware that the Local Universe is plenty of clustered structures and large voids, we compute the 2PACF with the Landy-Szalay estimator performing directional analyses to inspect 10 sky regions. We investigate these 2PACF using power-law best-fit analyses, and determine the statistical significance of the best-fit parameters for the 10 ALFALFA regions by comparison with the ones obtained through the same procedure applied to a set of mock catalogues produced under the homogeneity and isotropy hypotheses. Our conclusion is that the Local Universe, as mapped by the HI sources of the ALFALFA survey, is in agreement with the hypothesis of statistical isotropy within $2\sigma$ confidence level, for small and large angle analyses, with the only exception of one region -- located near the Dipole Repeller -- which appears slightly outlier ($2.4\sigma$). Interestingly, regarding the large angular distribution of the HI sources, we found 3 regions where the presence of cosmic voids reported in the literature left their signature in our 2PACF, suggesting projected large underdensities there, with number-density contrast $\delta \simeq -0.7$. According to the current literature these regions correspond, partially, to the sky position of the void structures known as Local Cosmic Void and Dipole Repeller.

arXiv comment14 pages, 13 figures, 2 appendices

References in corpus (69)

• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• The Arecibo Legacy Fast ALFA Survey: I. Science Goals, Survey Design and Strategy
• The large-scale structure of the Universe
• Cosmicflows-2: The Data
• The Arecibo Legacy Fast ALFA Survey: The ALFALFA Extragalactic HI Source Catalog
• Statistical Analysis of Galaxy Surveys - I. Robust error estimation for 2-point clustering statistics
• Our Peculiar Motion Away from the Local Void
• A Test of the Cosmological Principle with Quasars
• X-ray obscuration and obscured AGN in the local universe
• nbodykit: an open-source, massively parallel toolkit for large-scale structure
• Is the Observable Universe Consistent with the Cosmological Principle?
• Evidence for a ~300 Mpc Scale Under-density in the Local Galaxy Distribution
• Clues from nearby galaxies to a better theory of cosmic evolution
• Improving lognormal models for cosmological fields
• Evolution of One-Point Distributions from Gaussian Initial Fluctuations
• Cosmography of the Local Universe
• Properties of the Cosmological Density Distribution Function
• The Angular Correlation Function of Galaxies from Early SDSS Data
• Angular Baryon Acoustic Oscillation measure at z=2.225 from the SDSS quasar survey
• The Dipole Repeller
• Comparing approximate methods for mock catalogues and covariance matrices II: Power spectrum multipoles
• The Size and Shape of Local Voids
• Cosmicflows-3: Cosmography of the Local Void
• Comparing approximate methods for mock catalogues and covariance matrices I: correlation function
• CosmoBolognaLib: C++ libraries for cosmological calculations
• Comparing approximate methods for mock catalogues and covariance matrices III: Bispectrum
• The Local Hole revealed by galaxy counts and redshifts
• The clustering of ALFALFA galaxies: dependence on HI mass, relationship to optical samples & clues on host halo properties
• A ``Skewed'' lognormal approximation to the probability distribution function of the large-scale density field
• Observational evidence for a local underdensity in the Universe and its effect on the measurement of the Hubble Constant
• Back in the saddle: Large-deviation statistics of the cosmic log-density field
• The Clustering Characteristics of HI-Selected Galaxies from the 40% ALFALFA Survey
• Scale Dependent Galaxy Bias in the SDSS as a function of Luminosity and Colour
• BAO angular scale at z_eff = 0.11 with the SDSS blue galaxies
• Generating Log-normal Mock Catalog of Galaxies in Redshift Space
• Testing the Copernican Principle via Cosmological Observations
• The SDSS Galaxy Angular Two-Point Correlation Function
• On Statistical Lensing and the Anti-Correlation Between 2dF QSOs and Foreground Galaxies
• Extragalactic HI Surveys
• Parity Asymmetry in the CMBR Temperature Power Spectrum
• The HI Mass Function and Velocity Width Function of Void Galaxies in the Arecibo Legacy Fast ALFA Survey
• The growth rate of cosmic structures in the local Universe with the ALFALFA survey
• Testing Isotropy in the Local Universe
• Large Scale Structure of the Universe
• Measuring the scale of cosmic homogeneity with SDSS-IV DR14 quasars
• Cosmic homogeneity: a spectroscopic and model-independent measurement
• Tomographic analyses of the CMB lensing and galaxy clustering to probe the linear structure growth
• Testing the standard model of cosmology with the SKA: the cosmic radio dipole
• Estimating the galaxy two-point correlation function using a split random catalog
• Baryon acoustic oscillations signature in the three-point angular correlation function from the SDSS-DR12 quasar survey
• Probing cosmological isotropy with Planck Sunyaev-Zeldovich galaxy clusters
• CoLoRe: fast cosmological realisations over large volumes with multiple tracers
• The scale of homogeneity in the local Universe with the ALFALFA catalogue
• The angular scale of homogeneity in the Local Universe with the SDSS blue galaxies
• The homogeneity scale and the growth rate of cosmic structures
• On the large-scale angular distribution of short-Gamma ray bursts
• Isotropy analyses of the Planck convergence map
• Testing isotropy in the Universe using photometric and spectroscopic data from the SDSS
• Update on Testing the Isotropy of the Properties of Gamma-Ray Bursts
• New fitting formula for cosmic non-linear density distribution
• The galaxy luminosity function and the Local Hole
• Dust-Obscured Galaxies in the Local Universe
• The size of the longest filament in the Luminous Red Galaxy distribution
• Testing the Copernican and Cosmological Principles in the local universe with galaxy surveys
• Isotropy statistics of CMB hot and cold spots
• The bulk flow motion and the Hubble-Lema\^ıtre law in the Local Universe with the ALFALFA survey
• Detection of Dipole Modulation in CMB Temperature Anisotropy Maps from WMAP and Planck using Artificial Intelligence
• The maximum extent of the filaments and sheets in the cosmic web: an analysis of the SDSS DR17
• Level correlations of the CMB temperature angular power spectrum

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• Probing large-scale structures with the two-point function and the power spectrum: insights into cosmic clustering evolution
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