Cosmic filaments play a role of bridges along which matter and gas accrete onto galaxies to trigger star formation and feed central black holes. Here we explore the correlations between the intrinsic properties of void galaxies and the linearity R_L of void filaments (degree of filament's straightness). We focus on void regions since the bridge effect of filaments should be most conspicuous in the pristine underdense regions like voids. Analyzing the Millennium-Run semi-analytic galaxy catalogue, we identify void filaments consisting of more than four galaxies (three edges) and calculate the means of central black hole mass, star formation rate, and stellar mass as a function of R_L. It is shown that the void galaxies constituting more straight filaments tend to have higher luminosity, more massive central black holes and higher star formation rate. Among the three properties, the central black hole mass is most strongly correlated with R_L. It is also shown that the dark halos constituting straight filaments tend to have similar masses. Our results suggest that the fuel-supply for central black holes and star formation of void galaxies occurs most efficiently along straight void filaments whose potential wells are generated by similar-mass dark halos.
(abridged) We present the Significant Cosmic Holes in Universe (SCHU) method for identifying cosmic voids and loops of filaments in cosmological datasets and assigning their statistical significance using techniques from topological data analysis. Persistent homology is used to find different dimensional holes. For dark matter halo catalogs and galaxy surveys, the 0-, 1-, and 2-dimensional holes can be identified with clusters, loops of filaments, and voids. The procedure overlays halos/galaxies on a 3D grid, and a distance-to-measure (DTM) function is calculated at each point of the grid. A f…
Using computer simulations we study the geometry of a typical quantum universe, i.e. the geometry one might expect before a possible period of inflation. We display it using coordinates defined by means of four classical scalar fields satisfying the Laplace equation with non-trivial boundary conditions. The field configurations reveal cosmic web structures surprisingly similar to the ones observed in the present-day Universe. Inflation might make these structures relevant for our Universe.
Cosmic voids and the kinetic analysis. V. Hubble tension, the cosmological constant and aperiodic filaments
Center for Cosmology and Astrophysics, Alikhanian National Laboratory（阿利哈尼扬国家实验室宇宙学与天体物理中心）；Yerevan State University（埃里温国立大学）；Sapienza Universita di Roma（罗马智慧大学）；Keldysh Institute of Applied Mathematics of RAS（俄罗斯科学院凯尔迪什应用数学研究所）
We analyze the IllustrisTNG simulations to study the mass, volume fraction and phase distribution of gaseous baryons embedded in the knots, filaments, sheets and voids of the Cosmic Web from redshift $z=8$ to redshift $z=0$. We find that filaments host more star-forming gas than knots, and that filaments also have a higher relative mass fraction of gas in this phase than knots. We also show that the cool, diffuse Intergalactic Medium (IGM; $T<10^5 \, {\rm K}$, $ n_{\rm H}<10^{-4}(1+z) \, {\rm cm^{-3}}$) and the Warm-Hot Intergalactic Medium (WHIM; $ 10^5 \, {\rm K} <T<10^7 \, {\rm K}$, $ n_{\r…
The kinetic approach to the formation of the filaments in the large-scale matter distribution in the Universe is considered within the Vlasov formalism. The structures arise due to the self-consistent dynamics, along with the repulsive term in the modified Newtonian gravity which includes the cosmological constant. That modified gravity enables one to describe the Hubble tension as a result of two flows, the local and global ones. The criteria for formation of non--stationary semi-periodic structures in a system of gravitating particles described by Vlasov--Poisson equations are obtained in th…
Cosmicflows-3 distances and inferred peculiar velocities of galaxies have permitted the reconstruction of the structure of over and under densities within the volume extending to 0.05c. This study focuses on the under dense regions, particularly the Local Void that lies largely in the zone of obscuration and consequently has received limited attention. Major over dense structures that bound the Local Void are the Perseus-Pisces and Norma-Pavo-Indus filaments separated by 8,500 km/s. The void network of the universe is interconnected and void passages are found from the Local Void to the adjace…
We study the effect of baryons on the cosmic web -- halos, filaments, walls, and voids. To do so, we apply a modified version of NEXUS, a cosmic web morphological analysis algorithm, to the IllustrisTNG simulations. We find that halos lose more than $10\%$ of their mass due to baryons, mostly to filaments and a small portion to walls and voids. However, the mass transfer does not significantly shift the boundaries of structures, leaving the volume fractions of the cosmic structures largely unaffected. We quantify the effects of baryonic feedback on the power spectrum and the probability densit…
Focusing on both small separations and Baryonic Acoustic Oscillation scales, the cosmic evolution of the clustering properties of peak, void, wall, and filament-type critical points is measured using two-point correlation functions in $Λ$CDM dark matter simulations as a function of their relative rarity. A qualitative comparison to the corresponding theory for Gaussian Random fields allows us to understand the following observed features: i) the appearance of an exclusion zone at small separation, whose size depends both on rarity and on the signature (\ie the number of negative eigenvalues) o…
Cosmic voids are underdense regions filling up most of the volume in the Universe. They are expected to emerge in regions comprising negative initial density fluctuations, and subsequently expand as the matter around them collapses and forms walls, filaments and clusters. We report results from the analysis of a cosmological simulation specially designed to accurately describe low-density regions, such as cosmic voids. Contrary to the common expectation, we find that voids also experience significant mass inflows over cosmic history. On average, $10\%$ of the mass of voids in the sample at $z …
An Historical View: The Discovery of Voids in the Galaxy Distribution
在1978年发表的两篇论文中，星系大尺度分布中的空洞首次被认为是一种天体物理现象。我们发表了第一个（Gregory and Thompson，1978），Joeveer，Einasto and Tago（1978）发表了第二个。空洞的发现改变了公认的宇宙大尺度结构的观点。在旧的图像中，宇宙充满了场星系，偶尔可以在丰富的星系团或超星系团的位置发现密度增强。在新的图片中，空洞散布在复杂的超星系团结构之间，形成了所谓的宇宙网。发现空洞的关键观测先决条件是广角红移测量，显示为一个锥形图，延伸到足够远的距离，以显示宇宙的公平样本（即，远超本超星系团）。1978年空洞发现的最初影响被西方的理论宇宙学家推迟了好几年，他们不太确定细丝和空洞是如何从一个看起来均匀的宇宙中出现的。几年后，结构形成的理论模型可以解释这一现象，新的空洞和超星系团范式被广泛接受。
We investigate the basic properties of voids from high resolution, cosmological N-body simulations of Λ-dominated cold dark matter (ΛCDM) models, in order to compare with the analytical model of Sheth and van de Weygaert (SvdW) for void statistics. For the subsample of five dark matter simulations in the ΛCDM cosmology with box sizes ranging from 1000 Mpc/h to 8 Mpc/h, we find that the standard void-in-cloud effect is too simplified to explain several properties of identified small voids in simulations. (i) The number density of voids is found to be larger than the prediction of the analytical…
Using a set of high-resolution simulations we study the statistical correlation of dark matter halo properties with the large-scale environment. We consider halo populations split into four Cosmic Web (CW) elements: voids, walls, filaments, and nodes. For the first time we present a study of CW effects for halos covering six decades in mass: $10^{8}-10^{14}{h^{-1}{\rm M}_{\odot}}$. We find that the fraction of halos living in various web components is a strong function of mass, with the majority of $M>10^{12}{h^{-1}{\rm M}_{\odot}}$ halos living in filaments and nodes. Low mass halos are more …
The intrinsic alignments of galaxies, i.e., the correlation between galaxy shapes and their environment, are a major source of contamination for weak gravitational lensing surveys. Most studies of intrinsic alignments have so far focused on measuring and modelling the correlations of luminous red galaxies with galaxy positions or the filaments of the cosmic web. In this work, we investigate alignments around cosmic voids. We measure the intrinsic alignments of luminous red galaxies detected by the Sloan Digital Sky Survey around a sample of voids constructed from those same tracers and with ra…
Impact of the large-scale cosmic web on the X-ray emitting circumgalactic medium
Max Planck Institute for Extraterrestrial Physics（马克斯·普朗克地外物理研究所）；Yale University（耶鲁大学）；European Southern Observatory（欧洲南方天文台）；Institut d’Astrophysique de Paris（巴黎天体物理研究所）；INAF-Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）
We study biasing as a physical phenomenon by analysing power spectra (PS) and correlation functions (CF) of simulated galaxy samples and dark matter (DM) samples. We apply an algorithm based on the local densities of particles, $ρ$, to form populations of simulated galaxies, using particles with $ρ\ge ρ_0$. We calculate two-point CF of projected (2D) and spatial (3D) density fields of simulated galaxies for various particle-density limits $ρ_0$. We compare 3D and 2D CFs; in 2D case we use samples of various thickness to find the dependence of 2D CFs on thickness of samples. Dominant elements o…
Cosmic-web quenching with DESI DR1: T-Web environments and mass-dependent red/blue classification
Escuela de Física y Matemáticas del Instituto Politécnico Nacional（国立理工学院物理与数学学院）；Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional（国立理工学院高级研究中心物理系）；Tecnologico de Monterrey, Escuela de Ingeniería y Ciencias（蒙特雷科技大学工程与科学学院）
虚空星系位于宇宙网最深处的低密度区，是研究星系团和星系群中星系的复杂变化过程不受干扰的环境中星系形成和演化的理想群体，同时也为宇宙结构形成理论提供了观测检验。我们已经完成了一个新的虚空星系调查（VGS）的HI成像方面的试点调查，成像15个虚空星系在HI本地（d < 100 Mpc）空隙。HI的质量范围从3.5 x 10^8到3.8 x 10^9太阳质量，有一个未被探测到的质量上限为2.1 x 10^8太阳质量。我们的星系是使用结构和几何技术选择的，以产生一个纯粹的环境选择的样本，并均匀地代表了空星系的人口。此外，我们使用一个强大的新后端Westerbork合成射电望远镜，使我们能够探测每个目标星系周围的大体积，同时提供一个环境约束的前和背景控制样本的星系，同时仍然解决个别星系的运动学和检测微弱的同伴在HI。这个小样本组成了一个令人惊讶的有趣的受扰和相互作用的星系集合，所有星系都有小的恒星盘。四个星系有显着扰动HI盘，五个有以前身份不明的同伴在距离从50至200千秒差距，两个是在相互作用的系统，和一个被发现有一个极性HI盘。我们的初步研究结果表明，空星系是一个富含气体的，动态的人口，目前的证据正在进行的气体吸积，主要和次要的相互作用，以及尽管周围的密度不足的环境中的非线性对齐。
Evidence for a sign change of the ISW effect in the very recent universe? hot voids and cold overdensities at $z<0.03$
Institute of Theoretical Astrophysics, University of Oslo（奥斯陆大学理论天体物理研究所）；Instituto de Astronomía Teórica y Experimental, CONICET-UNC（CONICET-科尔多瓦大学理论与实验天文学研究所）；Observatorio Astronómico de Córdoba, UNC（科尔多瓦天文台，科尔多瓦大学）
By linking galaxies in Sloan Digital Sky Survey (SDSS) to subhaloes in the ELUCID simulation, we investigate the relation between subhalo formation time and the galaxy properties, and the dependence of galaxy properties on the cosmic web environment. We find that central and satellite subhaloes have different formation time, where satellite subhaloes are older than central subhaloes at fixed mass. At fixed mass, the galaxy stellar-to-subhalo mass ratio is a good proxy of the subhalo formation time, and increases with the subhalo formation redshifts, especially for massive galaxies. The subhalo…
Milky Way galaxy-analogs and isolated galaxies with bars: environmental density in the Local Volume
Main Astronomical Observatory of the National Academy of Sciences of Ukraine（乌克兰国家科学院主要天文台）；Institute of Astronomy of V. N. Karazin Kharkiv National University（哈尔科夫国立大学瓦西里·卡拉津天体物理研究所）
我们探索的结构和运动学之间的本地虚空和室女星系团居住的星系分散的灯丝。为此目的，我们考虑了在RA = [13.0.]的天区内的361个径向速度为$V_{LG} < 2000$ km/s的星系样本。18.0] $^h$和Dec.= [ $-$ 5. $+$ 10] $^\circ$。目前，其中161个有单独的距离估计。沿着这条带的星系分布以奇特的速度呈现出在RA 17 $^h$处已知的以室女座为中心的坍< 14 $^h$ and some signs of outflow from the Local Void at RA >缩。大多数牧夫座带状星系（56%）属于13个星系群和11对星系，其中最突出的星系群围绕着NGC 5846。牧夫座带星系群位于[17 $-$ 27]Mpc内，比室女星系团离我们更远。牧夫座暗条包含$2.7\times10^{12} M_\odot$的总恒星质量和$9.07\times10^{13} M_\odot$的总维里质量，暗物质的平均密度为$Ω_m = 0.09$，比全球宇宙平均密度低三倍。
We present a novel application of the extended Fast Action Minimization method (eFAM) aimed at assessing the role of the environment in shaping galaxy evolution. We validate our approach by testing eFAM predictions against the Magneticum hydrodynamical simulation. We consider the z~0 snapshot of the simulation as our observed catalogue and use the reconstructed trajectories of galaxies to model the evolution of cosmic structures. At the statistical level, the fraction of volume (VFF) occupied by voids, sheets, filaments, and clusters in the reconstructed catalogues agrees within $1σ$ with the …
We used dedicated SRG/eROSITA X-ray, ASKAP/EMU radio, and DECam optical observations of a 15 sq.deg region around the interacting galaxy cluster system A3391/95 to study the warm-hot gas in cluster outskirts and filaments, the surrounding large-scale structure and its formation process. We relate the observations to expectations from cosmological hydrodynamic simulations from the Magneticum suite. We trace the irregular morphology of warm-hot gas of the main clusters from their centers out to well beyond their characteristic radii, $r_{200}$. Between the two main cluster systems, we observe an…
We examine Suzaku, XMM-Newton, and Chandra observations of the Abell 2029/2033 system to investigate the nature of a bridge of X-ray emission joining the two galaxy clusters. By modelling the contributions from the outskirts of the two clusters, and excluding the emission from the southern infalling group and the background group LOS9, we find a significant excess of X-ray emission between the two clusters at the level of 6.5-7.0$σ$, depending on the choice of model, that cannot be explained by the overlap of the clusters. This excess component to the surface brightness is consistent with bein…
