Detection of cosmic filaments using the Candy model

Stoica, Radu; Martı́nez, Vicent J.; Mateu, Jorge; Saar, E.

doi:10.1051/0004-6361:20042409

Cited by 86 publications

(95 citation statements)

References 32 publications

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“…Methods to quantify the cosmic web abound (Stoica et al 2005;Shen et al 2006;Aragón-Calvo et al 2007;Hahn et al 2007;Sousbie et al 2008;Forero-Romero et al 2009;Hoffman et al 2012;Libeskind et al 2012Libeskind et al , 2013Tempel et al 2014a) depending on the data and problem at hand. In general, the methods based on simulations rely on a more complete knowledge of the cosmic fluid than what is usually available in observations.…”

Section: Introductionmentioning

confidence: 99%

The alignment of galaxy spin with the shear field in observations

Pahwa

Libeskind

Tempel

et al. 2016

Mon. Not. R. Astron. Soc.

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Tidal torque theory suggests that galaxies gain angular momentum in the linear stage of structure formation. Such a theory predicts alignments between the spin of haloes and tidal shear field. However, non-linear evolution and angular momentum acquisition may alter this prediction significantly. In this paper, we use a reconstruction of the cosmic shear field from observed peculiar velocities combined with spin axes extracted from galaxies within 115 Mpc (∼ 8000 kms −1 ) from 2MRS catalog, to test whether or not galaxies appear aligned with principal axes of shear field. Although linear reconstructions of the tidal field have looked at similar issues, this is the first such study to examine galaxy alignments with velocity-shear field. Ellipticals in the 2MRS sample, show a statistically significant alignment with two of the principal axes of the shear field. In general, elliptical galaxies have their short axis aligned with the axis of greatest compression and perpendicular to the axis of slowest compression. Spiral galaxies show no signal. Such an alignment is significantly strengthened when considering only those galaxies that are used in velocity field reconstruction. When examining such a subsample, a weak alignment with the axis of greatest compression emerges for spiral galaxies as well. This result indicates that although velocity field reconstructions still rely on fairly noisy and sparse data, the underlying alignment with shear field is strong enough to be visible even when small numbers of galaxies are considered -especially if those galaxies are used as constraints in the reconstruction.

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Section: Introductionmentioning

confidence: 99%

The alignment of galaxy spin with the shear field in observations

Pahwa

Libeskind

Tempel

et al. 2016

Mon. Not. R. Astron. Soc.

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“…COSMIC WEB CLASSIFICATION SCHEME With the rich and complex of the cosmic web, there are numerous methods by which one can classify the elements of the cosmic web. These range from techniques utilizing minimal-spanning trees (Barrow et al 1985;Alpaslan et al 2014), the Candy model (Stoica et al 2005(Stoica et al , 2010, Morse theory-based 'skeleton' methods (Colombi et al 2000;Novikov et al 2006;Sousbie et al 2009;Sousbie 2011), tessellation methods (González & Padilla 2010), multi-scale morphological methods (Aragón-Calvo 6 http://tinyurl.com/lya-tomography-sim-data et al 2007Cautun et al 2013), ridge-finding (Chen et al 2015), and others; (see Cautun et al 2014, for a comprehensive summary).…”

Section: Simulationsmentioning

confidence: 99%

REVEALING THE z ∼ 2.5 COSMIC WEB WITH 3D Lyα FOREST TOMOGRAPHY: A DEFORMATION TENSOR APPROACH

Lee

White

2016

ApJ

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Studies of cosmological objects should take into account their positions within the cosmic web of largescale structure. Unfortunately, the cosmic web has only been extensively mapped at low-redshifts (z < 1), using galaxy redshifts as tracers of the underlying density field. At z > 1, the required galaxy densities are inaccessible for the foreseeable future, but 3D reconstructions of Lyα forest absorption in closely-separated background QSOs and star-forming galaxies already offer a detailed window into z ∼ 2 − 3 large-scale structure. We quantify the utility of such maps for studying the cosmic web by using realistic z = 2.5 Lyα forest simulations matched to observational properties of upcoming surveys. A deformation tensor-based analysis is used to classify voids, sheets, filaments and nodes in the flux, which is compared to those determined from the underlying dark matter field. We find an extremely good correspondence, with 70% of the volume in the flux maps correctly classified relative to the dark matter web, and 99% classified to within 1 eigenvalue. This compares favorably to the performance of galaxy-based classifiers with even the highest galaxy densities from low-redshift surveys. We find that narrow survey geometries can degrade the cosmic web recovery unless the survey is 60 h −1 Mpc or 1 deg on the sky. We also examine halo abundances as a function of the cosmic web, and find a clear dependence as a function of flux overdensity, but little explicit dependence on the cosmic web. These methods will provide a new window on cosmological environments of galaxies at this very special time in galaxy formation, "high noon", and on overall properties of cosmological structures at this epoch.

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“…This is computationally intensive but quite effective, though it does depend on the artefacts in the reconstruction of the continuous density field. Stoica et al (2005) use a generalization of the classical Candy model to locate and catalogue filaments in galaxy surveys. This appraoch has the advantage that it works directly with the original point process and does not require the creation of a continuous density field.…”

Section: Cluster and Filament Findingmentioning

confidence: 99%