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We investigate the topology of the completed 2dF Galaxy Redshift Survey, drawing two flux-limited samples of the local Universe from the 2dFGRS catalogue, which contains over 220,000 galaxies at a median redshift of z = 0.11. The samples…

Astrophysics · Physics 2008-11-26 J. Berian James , Geraint F. Lewis , Matthew Colless

Void number counts (VNC) indicates the number of low-density regions in the large-scale structure (LSS) of the Universe, and we propose to use it as an effective cosmological probe. By generating the galaxy mock catalog based on Jiutian…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-06 Yingxiao Song , Qi Xiong , Yan Gong , Furen Deng , Kwan Chuen Chan , Xuelei Chen , Qi Guo , Yun Liu , Wenxiang Pei

We measure the void size function (VSF) from the Baryon Oscillation Spectroscopic Survey (BOSS DR16) and perform the cosmological constraints. The BOSS DR16 galaxy sample is selected in the redshift range from $z = 0.2$ to 0.8, considering…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-04 Yingxiao Song , Yan Gong , Xingchen Zhou , Haitao Miao , Kwan Chuen Chan , Xuelei Chen

The characterisation of cosmic voids gives unique information about the large-scale distribution of galaxies, their evolution and the cosmological model. We identify and characterise cosmic voids in the VIMOS Public Extragalactic Redshift…

We present a general analytical formalism to calculate accurately several statistics related to underdense regions in the Universe. The statistics are computed for dark matter halo and galaxy distributions both in real space and redshift…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Juan Betancort-Rijo , Santiago G. Patiri , Francisco Prada , Antonio Enea Romano

Persistent Homology (PH) has been successfully used to train networks to detect curvilinear structures and to improve the topological quality of their results. However, existing methods are very global and ignore the location of topological…

Computer Vision and Pattern Recognition · Computer Science 2022-12-27 Doruk Oner , Adélie Garin , Mateusz Koziński , Kathryn Hess , Pascal Fua

Persistent Homology (PH) is a fundamental tool in computational topology, designed to uncover the intrinsic geometric and topological features of data across multiple scales. Originating within the broader framework of Topological Data…

Algebraic Topology · Mathematics 2025-05-13 Aurelie Jodelle Kemme , Collins Amburo Agyingi

Topological data analysis (TDA) is a rising branch in modern applied mathematics. It extracts topological structures as features of a given space and uses these features to analyze digital data. Persistent homology, one of the central tools…

Algebraic Topology · Mathematics 2025-05-26 Chuan-Shen Hu

We use the WISE-2MASS infrared galaxy catalog matched with Pan-STARRS1 (PS1) galaxies to search for a supervoid in the direction of the Cosmic Microwave Background Cold Spot. Our imaging catalog has median redshift $z\simeq 0.14$, and we…

Feature selection is an important tool to deal with high dimensional data. In unsupervised case, many popular algorithms aim at maintaining the structure of the original data. In this paper, we propose a simple and effective feature…

Machine Learning · Statistics 2020-04-06 Xiaoyun Li , Chengxi Wu , Ping Li

Hyperuniformity, the suppression of density fluctuations at large length scales, is observed across a wide variety of domains, from cosmology to condensed matter and biological systems. Although the standard definition of hyperuniformity…

Statistical Mechanics · Physics 2024-05-07 Marco Salvalaglio , Dominic J. Skinner , Jörn Dunkel , Axel Voigt

Persistent homology (PH) is a rigorous mathematical theory that provides a robust descriptor of data in the form of persistence diagrams (PDs) which are 2D multisets of points. Their variable size makes them, however, difficult to combine…

Machine Learning · Statistics 2019-06-14 Bartosz Zielinski , Michal Lipinski , Mateusz Juda , Matthias Zeppelzauer , Pawel Dlotko

Point-cloud persistent homology (PH) -- computing alpha or Rips complexes on spin-position point clouds -- has been widely applied to detect phase transitions in classical spin models since Donato et al. (2016), with subsequent studies…

Statistical Mechanics · Physics 2026-04-01 Matthew Loftus

Eulerian cosmological codes are especially suited to properly describe the low density regions. This property makes this class of codes excellent tools to study the formation and evolution of cosmic voids. Following such ideas, we present…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 E. Ricciardelli , V. Quilis , S. Planelles

We investigate the large scale matter distribution adopting QSOs as matter tracer. The quasar catalogue based on the SDSS DR7 is used. The void finding algorithm is presented and statistical properties of void sizes and shapes are…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-04 A. M. Sołtan

We present DisPerSE, a novel approach to the coherent multi-scale identification of all types of astrophysical structures, and in particular the filaments, in the large scale distribution of matter in the Universe. This method and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Thierry Sousbie

Using two-dimensional numerical simulations of gravitational clustering, with initial power spectra of a power-law form with index n, we compare the properties of voids in real space to their properties in redshift space. Both the void…

Astrophysics · Physics 2009-10-28 Barbara Ryden , Adrian Melott

Recent observational results suggest that our universe is nearly flat and well modelled within a $\Lambda$CDM framework. The observed values of $\Omega_{m}$ and $\Omega_{\Lambda}$ inevitably involve uncertainties. Motivated by this, we make…

General Relativity and Quantum Cosmology · Physics 2009-11-10 B. Mota , M. J. Reboucas , R. Tavakol

We have analyzed the distribution of void sizes in the two-dimensional slices of the Las Campanas Redshift Survey (LCRS). Fourteen volume-limited subsamples were extracted from the six slices to cover a large part of the survey and to test…

Astrophysics · Physics 2009-07-30 V. Mueller , S. Arbabi-Bidgoli , J. Einasto , D. Tucker