T-ReX: a graph-based filament detection method

Context. Superclusters of galaxies and their surrounding low-density regions (cocoons) represent dynamically evolving environments in which galaxies and their systems form and evolve. While evolutionary processes of galaxies in dense environments are extensively studied at present, galaxy evolution in low-density regions has received less attention. Aims. We study the properties, connectivity, and galaxy content of groups and filaments in the A2142 supercluster (SCl A2142) cocoon to understand the evolution of the supercluster with its surrounding structures and the galaxies within them. Methods. We calculated the luminosity-density field of SDSS galaxies and traced the SCl A2142 cocoon boundaries by the lowest luminosity-density regions that separate SCl A2142 from other superclusters. We determined galaxy filaments and groups in the cocoon and analysed the connectivity of groups, the high density core (HDC) of the supercluster, and the whole of the supercluster. We compared the distribution and properties of galaxies with different star-formation properties in the supercluster and in the cocoon. Results. The supercluster A2142 and the long filament that is connected to it forms the longest straight structure in the Universe detected so far, with a length of approximately 75 h −1 Mpc. The connectivity of the cluster A2142 and the whole supercluster is C = 6 − 7; poor groups exhibit C = 1 − 2. Long filaments around the supercluster's main body are detached from it at the turnaround region. Among various local and global environmental trends with regard to the properties of galaxies and groups, we find that galaxies with very old stellar populations lie in systems across a wide range of richness from the richest cluster to poorest groups and single galaxies. They lie even at local densities as low as D1 < 1 in the cocoon and up to D1 > 800 in the supercluster. Recently quenched galaxies lie in the cocoon mainly in one region and their properties are different in the cocoon and in the supercluster. The star-formation properties of single galaxies are similar across all environments. Conclusions. The collapsing main body of SCl A2142 with the detached long filaments near it are evidence of an important epoch in the supercluster evolution. There is a need for further studies to explore possible reasons behind the similarities between galaxies with very old stellar populations in extremely different environments, as well as mechanisms for galaxy quenching at very low densities. The presence of long, straight structures in the cosmic web may serve as a test for cosmological models.

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“…This is shown, for example, in Fig. 16 by Bonnaire et al (2020), and in Fig. 4 by Ganeshaiah Veena et al (2019).…”

Section: Filaments and Groups In The Supercluster And In The Cocoonmentioning

confidence: 73%

Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SCl A2142 cocoon

Einasto

Deshev

Tenjes

et al. 2020

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“…This paper provides several reference catalogues with which studies of the cosmic web can be performed and with which the development of new tools can be compared (e.g. Bonnaire et al 2020). Fig.…”

Section: Conclusion and Summarymentioning

confidence: 99%

Characterising filaments in the SDSS volume from the galaxy distribution

Malavasi

Aghanim

Douspis

et al. 2020

A&A

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Detecting the large-scale structure of the Universe based on the galaxy distribution and characterising its components is of fundamental importance in astrophysics but is also a difficult task to achieve. Wide-area spectroscopic redshift surveys are required to accurately measure galaxy positions in space that also need to cover large areas of the sky. It is also difficult to create algorithms that can extract cosmic web structures (e.g. filaments). Moreover, these detections will be affected by systematic uncertainties that stem from the characteristics of the survey used (e.g. its completeness and coverage) and from the unique properties of the specific method adopted to detect the cosmic web (i.e. the assumptions it relies on and the free parameters it may employ). For these reasons, the creation of new catalogues of cosmic web features on wide sky areas is important, as this allows users to have at their disposal a well-understood sample of structures whose systematic uncertainties have been thoroughly investigated. In this paper we present the filament catalogues created using the discrete persistent structure extractor tool in the Sloan Digital Sky Survey (SDSS), and we fully characterise them in terms of their dependence on the choice of parameters pertaining to the algorithm, and with respect to several systematic issues that may arise in the skeleton as a result of the properties of the galaxy distribution (such as Finger-of-God redshift distortions and defects of the density field that are due to the boundaries of the survey).

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“…Several algorithms, which detect filaments using various approaches, have been developed to overcome these limitations. For example, filaments can be defined based on the topology of the matter density field, on density thresholds, on the velocity field, or even with a probabilistic approach (see for example Aragón-Calvo et al 2010;Sousbie 2011;Sousbie et al 2011;Cautun et al 2013;Libeskind et al 2018;Bonnaire et al 2020;Pereyra et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…On scales of tens of megaparsecs, longer filaments have been detected by applying different filament finders (e.g. Sousbie 2011;Sousbie et al 2011;Cautun et al 2013;Tempel et al 2016;Bonnaire et al 2020) has enabled the study of the properties of galaxies (e.g. Alpaslan et al 2016;Malavasi et al 2017;Chen et al 2017;Laigle et al 2018;Kraljic et al 2018;Sarron et al 2019;Malavasi et al 2020a;Rost et al 2020;Bonjean et al 2020;Welker et al 2020), and gas in filaments (Tanimura et al 2020a,b).…”

Section: Introductionmentioning

confidence: 99%

Properties of gas phases around cosmic filaments atz= 0 in the IllustrisTNG simulation

Galárraga-Espinosa

Aghanim

Langer

et al. 2021

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We present the study of gas phases around cosmic-web filaments detected in the TNG300-1 hydro-dynamical simulation at redshift z = 0. We separate the gas into five different phases according to temperature and density. We show that filaments are essentially dominated by gas in the warm-hot intergalactic medium (WHIM), which accounts for more than 80% of the baryon budget at r ∼ 1 Mpc. Apart from WHIM gas, cores of filaments (r ≤ 1 Mpc) also host large contributions from other hotter and denser gas phases, whose fractions depend on the filament population. By building temperature and pressure profiles, we find that gas in filaments is isothermal up to r ∼ 1.5 Mpc, with average temperatures of Tcore = 4−13 × 105 K, depending on the large-scale environment. Pressure at cores of filaments is on average Pcore = 4−12 × 10−7 keV.cm−3, which is ∼1000 times lower than pressure measured in observed clusters. We also estimate that the observed Sunyaev-Zel’dovich signal from cores of filaments should range between 0.5 < y < 4.1 × 10−8, and these results are compared with recent observations. Our findings show that the state of the gas in filaments depends on the presence of haloes and on the large-scale environment.

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T-ReX: a graph-based filament detection method

Cited by 53 publications

References 74 publications

Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SCl A2142 cocoon

Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SCl A2142 cocoon

Characterising filaments in the SDSS volume from the galaxy distribution

Properties of gas phases around cosmic filaments atz= 0 in the IllustrisTNG simulation

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