| Issue |
A&A
Volume 651, July 2021
|
|
|---|---|---|
| Article Number | A15 | |
| Number of page(s) | 7 | |
| Section | Cosmology (including clusters of galaxies) | |
| DOI | https://doi.org/10.1051/0004-6361/202140595 | |
| Published online | 05 August 2021 | |
The Cosmic Large-Scale Structure in X-rays (CLASSIX) Cluster Survey
II. Unveiling a pancake structure with a 100 Mpc radius in the local Universe⋆
1
Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstr. 1, 81679 München, Germany
2
Max-Planck-Institut für Extraterrestrische Physik, 85748 Garching, Germany
e-mail: hxb@mpe.mpg.de
Received:
17
February
2021
Accepted:
23
March
2021
Previous studies of the galaxy and galaxy cluster distribution in the local Universe found indications for a large extension of the Local Supercluster up to a radius of 190 h70−1 Mpc. We are using our large and highly complete CLASSIX survey of X-ray luminous galaxy clusters detected in the ROSAT All Sky Survey to trace the matter distribution in the local Universe and to explore the size of the flattened local density structure associated with the Local Supercluster. The Local Supercluster is oriented almost perpendicular to the Galactic plane. Since Galactic extinction increases towards the Galactic plane, objects are on average more easily visible perpendicular to the plane than close to it, also producing an apparent concentration of objects along the Local Supercluster. We can correct for this bias by a careful treatment of the survey selection function. We find a significant overdensity of clusters in a flattened structure along the Supergalactic plane with a thickness of about 50 Mpc and an extent of about 100 Mpc radius. Structures at a distance larger than 100 Mpc are not correlated to the Local Supercluster any more. The matter density contrast of the local superstructure to the surroundings is about a factor of 1.3−2.3. Within the Supergalactic plane the matter is concentrated mostly in two superclusters, the Perseus-Pices Chain and Hydra-Centaurus supercluster. We have shown in our earlier work that the local Universe in a region with a radius of 100−170 Mpc has a lower density than the cosmic mean. For this reason, the Local Supercluster is not overdense with respect to the cosmic mean density. Therefore this local superstructure will not collapse as a whole in the future, but rather fragment.
Key words: galaxies: clusters: general / cosmology: observations / large-scale structure of Universe / X-rays: galaxies: clusters
© H. Böhringer et al. 2021
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Open Access funding provided by Max Planck Society.
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