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Title: Sparse Reconstruction of the Merging A520 Cluster System

Abstract

Merging galaxy clusters present a unique opportunity to study the properties of dark matter in an astrophysical context. These are rare and extreme cosmic events in which the bulk of the baryonic matter becomes displaced from the dark matter halos of the colliding subclusters. Since all mass bends light, weak gravitational lensing is a primary tool to study the total mass distribution in such systems. Combined with X-ray and optical analyses, mass maps of cluster mergers reconstructed from weak-lensing observations have been used to constrain the self-interaction cross-section of dark matter. The dynamically complex Abell 520 (A520) cluster is an exceptional case, even among merging systems: multi-wavelength observations have revealed a surprising high mass-to-light concentration of dark mass, the interpretation of which is difficult under the standard assumption of effectively collisionless dark matter. We revisit A520 using a new sparsity-based mass-mapping algorithm to independently assess the presence of the puzzling dark core. We obtain high-resolution mass reconstructions from two separate galaxy shape catalogs derived from Hubble Space Telescope observations of the system. Our mass maps agree well overall with the results of previous studies, but we find important differences. In particular, although we are able to identify the dark coremore » at a certain level in both data sets, it is at much lower significance than has been reported before using the same data. As we cannot confirm the detection in our analysis, we do not consider A520 as posing a significant challenge to the collisionless dark matter scenario.« less

Authors:
 [1];  [2];  [3]
  1. Département d’Astrophysique, IRFU, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette (France)
  2. McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States)
  3. Université Paris Diderot, AIM, Sorbonne Paris Cité, CEA, CNRS, F-91191 Gif-sur-Yvette (France)
Publication Date:
OSTI Identifier:
22679838
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 847; 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; ASTROPHYSICS; BARYONS; CONCENTRATION RATIO; DETECTION; ELEMENT ABUNDANCE; GALAXIES; GALAXY CLUSTERS; GRAVITATIONAL LENSES; INTERACTIONS; MASS; MASS DISTRIBUTION; NONLUMINOUS MATTER; RESOLUTION; TELESCOPES; VISIBLE RADIATION; WAVELENGTHS; X RADIATION

Citation Formats

Peel, Austin, Lanusse, François, and Starck, Jean-Luc. Sparse Reconstruction of the Merging A520 Cluster System. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA850D.
Peel, Austin, Lanusse, François, & Starck, Jean-Luc. Sparse Reconstruction of the Merging A520 Cluster System. United States. https://doi.org/10.3847/1538-4357/AA850D
Peel, Austin, Lanusse, François, and Starck, Jean-Luc. 2017. "Sparse Reconstruction of the Merging A520 Cluster System". United States. https://doi.org/10.3847/1538-4357/AA850D.
@article{osti_22679838,
title = {Sparse Reconstruction of the Merging A520 Cluster System},
author = {Peel, Austin and Lanusse, François and Starck, Jean-Luc},
abstractNote = {Merging galaxy clusters present a unique opportunity to study the properties of dark matter in an astrophysical context. These are rare and extreme cosmic events in which the bulk of the baryonic matter becomes displaced from the dark matter halos of the colliding subclusters. Since all mass bends light, weak gravitational lensing is a primary tool to study the total mass distribution in such systems. Combined with X-ray and optical analyses, mass maps of cluster mergers reconstructed from weak-lensing observations have been used to constrain the self-interaction cross-section of dark matter. The dynamically complex Abell 520 (A520) cluster is an exceptional case, even among merging systems: multi-wavelength observations have revealed a surprising high mass-to-light concentration of dark mass, the interpretation of which is difficult under the standard assumption of effectively collisionless dark matter. We revisit A520 using a new sparsity-based mass-mapping algorithm to independently assess the presence of the puzzling dark core. We obtain high-resolution mass reconstructions from two separate galaxy shape catalogs derived from Hubble Space Telescope observations of the system. Our mass maps agree well overall with the results of previous studies, but we find important differences. In particular, although we are able to identify the dark core at a certain level in both data sets, it is at much lower significance than has been reported before using the same data. As we cannot confirm the detection in our analysis, we do not consider A520 as posing a significant challenge to the collisionless dark matter scenario.},
doi = {10.3847/1538-4357/AA850D},
url = {https://www.osti.gov/biblio/22679838}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 847,
place = {United States},
year = {Wed Sep 20 00:00:00 EDT 2017},
month = {Wed Sep 20 00:00:00 EDT 2017}
}