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The assumption that the universe is homogeneous and isotropic on large scales is one of the fundamental postulates of cosmology. We have tested the large scale homogeneity of the galaxy distribution in the Sloan Digital Sky Survey Data…

Astrophysics · Physics 2009-11-11 J. Yadav , S. Bharadwaj , B. Pandey , T. R. Seshadri

We quantify the degree of inhomogeneity in the Luminous Red Galaxy (LRG) distribution from the SDSS DR7 as a function of length scales by measuring the Shannon entropy in independent and regular cubic voxels of increasing grid sizes. We…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-25 Biswajit Pandey , Suman Sarkar

We analyze a set of volume limited sample of galaxies from the SDSS to study the issue of cosmic homogeneity. We use the Renyi entropy of different order to probe the inhomogeneties present in the galaxy distributions. We also calculate the…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-21 Biswajit Pandey , Suman Sarkar

The assumption that the Universe, on sufficiently large scales, is homogeneous and isotropic is crucial to our current understanding of cosmology. In this paper we test if the observed galaxy distribution is actually homogeneous on large…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Prakash Sarkar , Jaswant Yadav , Biswajit Pandey , Somnath Bharadwaj

We analyze the SDSS DR12 quasar catalogue to test the large-scale smoothness in the quasar distribution. We quantify the degree of inhomogeneity in the quasar distribution using information theory based measures and find that the degree of…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-21 Suman Sarkar , Biswajit Pandey

We propose a method for testing cosmic homogeneity based on the Shannon entropy in Information theory and test the potentials and limitations of the method on Monte Carlo simulations of some homogeneous and inhomogeneous 3D point process in…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Biswajit Pandey

We analyze two volume limited galaxy samples from the SDSS photometric and spectroscopic data to test the isotropy in the local Universe. We use information entropy to quantify the global anisotropy in the galaxy distribution at different…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-12 Suman Sarkar , Biswajit Pandey , Rishi Khatri

The properties of the galaxy distribution at large scales are usually studied using statistics which are assumed to be self-averaging inside a given sample. We present a new analysis able to quantitatively map galaxy large scale structures…

We carry out multifractal analyses of multiple tracers namely the main galaxy sample, the LRG sample and the quasar sample from the SDSS to test the assumption of cosmic homogeneity and identify the scale of transition to homogeneity, if…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-24 Prakash Sarkar , Subhabrata Majumdar , Biswajit Pandey , Atul Kedia , Suman Sarkar

We discuss some of the basic implications of recent results on galaxy correlations published by the SDSS collaboration. In particular we focus on the evidence which has been recently presented for the scale and nature of the transition to…

Astrophysics · Physics 2009-11-10 M. Joyce , F. Sylos Labini , A. Gabrielli , M. Montuori , L. Pietronero

We analyze a volume limited galaxy sample from the SDSS to study the environments of galaxies on different length scales in the local Universe. We measure the local dimension of the SDSS galaxies on different length scales and find that the…

Cosmology and Nongalactic Astrophysics · Physics 2019-04-10 Suman Sarkar , Biswajit Pandey

In this study, we probe the transition to cosmic homogeneity in the Large Scale Structure (LSS) of the Universe using the CMASS galaxy sample of BOSS spectroscopic survey which covers the largest effective volume to date, $3\ h^{-3}\…

According to the cosmological principle, galaxy cluster sizes and cluster densities, when averaged over sufficiently large volumes of space, are expected to be constant everywhere, except for a slow variation with look-back time (redshift).…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-03 Michael J. Longo

We report measurements of the scale of cosmic homogeneity ($r_{h}$) using the recently released quasar sample of the sixteenth data release of the Sloan Digital Sky Survey (SDSS-IV DR16). We perform our analysis in 2 redshift bins lying in…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-04 Rodrigo S. Gonçalves , Gabriela C. Carvalho , Uendert Andrade , Carlos A. P. Bengaly , Joel C. Carvalho , Jailson Alcaniz

Statistical analyses of finite sample distributions usually assume that fluctuations are self-averaging, i.e. that they are statistically similar in different regions of the given sample volume. By using the scale-length method, we test…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-02 Francesco Sylos Labini , Nikolay L. Vasilyev , Yurij V. Baryshev

We have analyzed the spatial distribution of galaxies from the release of the Sloan Digital Sky Survey of galactic redshifts (SDSS DR7), applying the complete correlation function (conditional density), two-point conditional density…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 A. O. Verevkin , Yu. L. Bukhmastova , Yu. V. Baryshev

We propose a method for testing homogeneity in three dimensional spatial distributions using Renyi entropy. We apply the proposed method to data from cosmological N-body simulations and Monte Carlo simulations of homogeneous Poisson point…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-16 Biswajit Pandey

The Millennium N-body simulation and the Sloan Digital Sky Survey seventh data release (SDSS DR7) galaxy and galaxy group catalogues are compared to study the properties of galaxy groups and the distribution of galaxies in groups. We…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-29 P. Nurmi , P. Heinämäki , T. Sepp , E. Tago , E. Saar , M. Gramann , M. Einasto , E. Tempel , J. Einasto

We test the homogeneity of the Universe at $z\sim 0.3$ with the Luminous Red Galaxy (LRG) spectroscopic sample of the Sloan Digital Sky Survey. First, the mean number $N(R)$ of LRGs within completely surveyed LRG-centered spheres of…

Observationally confirming spatial homogeneity on sufficiently large cosmological scales is of importance to test one of the underpinning assumptions of cosmology, and is also imperative for correctly interpreting dark energy. A challenging…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Ben Hoyle , Rita Tojeiro , Raul Jimenez , Alan Heavens , Chris Clarkson , Roy Maartens
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