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Title: THE LOCAL GROUP IN THE COSMIC WEB

Abstract

We explore the characteristics of the cosmic web around Local-Group (LG)-like pairs using a cosmological simulation in the ΛCDM cosmology. We use the Hessian of the gravitational potential to classify regions on scales of ∼2 Mpc as a peak, sheet, filament, or void. The sample of LG counterparts is represented by two samples of halo pairs. The first is a general sample composed of pairs with similar masses and isolation criteria as observed for the LG. The second is a subset with additional observed kinematic constraints such as relative pair velocity and separation. We find that the pairs in the LG sample with all constraints are: (1) preferentially located in filaments and sheets, (2) located in a narrow range of local overdensity 0 < δ < 2, web ellipticity 0.1 < e < 1.0, and prolateness –0.4 < p < 0.4, (3) strongly aligned with the cosmic web. The alignments are such that the pair orbital angular momentum tends to be perpendicular to the smallest tidal eigenvector, e-hat {sub 3}, which lies along the filament direction or the sheet plane. A stronger alignment is present for the vector linking the two halos with the vector e-hat {sub 3}. Additionally, we failmore » to find a strong correlation between the spin of each halo in the pair with the cosmic web. All of these trends are expected to a great extent from the selection of LG total mass in the general sample. Applied to the observed LG, there is a potential conflict between the alignments of the different satellite planes and the numerical evidence for satellite accretion along filaments; the direction defined by e-hat {sub 3}. This highlights the relevance of achieving a precise characterization for the location of the LG in the cosmic web in the cosmological context provided by ΛCDM.« less

Authors:
 [1]
  1. Departamento de Física, Universidad de los Andes, Cra. 1 No. 18A-10, Edificio Ip, Bogotá (Colombia)
Publication Date:
OSTI Identifier:
22364534
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALIGNMENT; COMPUTERIZED SIMULATION; CORRELATIONS; COSMOLOGICAL CONSTANT; COSMOLOGY; EIGENVECTORS; FILAMENTS; GALAXIES; GRAVITATIONAL INTERACTIONS; LIMITING VALUES; MASS; NONLUMINOUS MATTER; ORBITAL ANGULAR MOMENTUM; POTENTIALS; SATELLITES; SPIN

Citation Formats

Forero-Romero, J. E., and González, R., E-mail: je.forero@uniandes.edu.co, E-mail: regonzar@astro.puc.cl. THE LOCAL GROUP IN THE COSMIC WEB. United States: N. p., 2015. Web. doi:10.1088/0004-637X/799/1/45.
Forero-Romero, J. E., & González, R., E-mail: je.forero@uniandes.edu.co, E-mail: regonzar@astro.puc.cl. THE LOCAL GROUP IN THE COSMIC WEB. United States. https://doi.org/10.1088/0004-637X/799/1/45
Forero-Romero, J. E., and González, R., E-mail: je.forero@uniandes.edu.co, E-mail: regonzar@astro.puc.cl. 2015. "THE LOCAL GROUP IN THE COSMIC WEB". United States. https://doi.org/10.1088/0004-637X/799/1/45.
@article{osti_22364534,
title = {THE LOCAL GROUP IN THE COSMIC WEB},
author = {Forero-Romero, J. E. and González, R., E-mail: je.forero@uniandes.edu.co, E-mail: regonzar@astro.puc.cl},
abstractNote = {We explore the characteristics of the cosmic web around Local-Group (LG)-like pairs using a cosmological simulation in the ΛCDM cosmology. We use the Hessian of the gravitational potential to classify regions on scales of ∼2 Mpc as a peak, sheet, filament, or void. The sample of LG counterparts is represented by two samples of halo pairs. The first is a general sample composed of pairs with similar masses and isolation criteria as observed for the LG. The second is a subset with additional observed kinematic constraints such as relative pair velocity and separation. We find that the pairs in the LG sample with all constraints are: (1) preferentially located in filaments and sheets, (2) located in a narrow range of local overdensity 0 < δ < 2, web ellipticity 0.1 < e < 1.0, and prolateness –0.4 < p < 0.4, (3) strongly aligned with the cosmic web. The alignments are such that the pair orbital angular momentum tends to be perpendicular to the smallest tidal eigenvector, e-hat {sub 3}, which lies along the filament direction or the sheet plane. A stronger alignment is present for the vector linking the two halos with the vector e-hat {sub 3}. Additionally, we fail to find a strong correlation between the spin of each halo in the pair with the cosmic web. All of these trends are expected to a great extent from the selection of LG total mass in the general sample. Applied to the observed LG, there is a potential conflict between the alignments of the different satellite planes and the numerical evidence for satellite accretion along filaments; the direction defined by e-hat {sub 3}. This highlights the relevance of achieving a precise characterization for the location of the LG in the cosmic web in the cosmological context provided by ΛCDM.},
doi = {10.1088/0004-637X/799/1/45},
url = {https://www.osti.gov/biblio/22364534}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 799,
place = {United States},
year = {Tue Jan 20 00:00:00 EST 2015},
month = {Tue Jan 20 00:00:00 EST 2015}
}