What is it about?

Our analysis of the structure of galaxy supercluster A2142, hosting rich galaxy cluster Abell 2142, revealed that collapsing main body of the supercluster together with galaxy filament connected to it forms the longest straight structure in the Universe discovered so far, with length of 250 million light years. Galaxies with very old stellar populations lie both in clusters and groups of the supercluster, as well as in the poorest groups in the low density regions around it.

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Why is it important?

Galaxy superclusters with their complex inner structure, where rich galaxy clusters are connected by filaments of galaxies and galaxy groups are ideal laboratories to study the evolution of galaxies and galaxy clusters within them. Central regions of rich galaxy clusters are populated by galaxies with very old stellar populations, where star formation in galaxies have stopped under the influence of neighbouring galaxies in the crowded environment of clusters, stripping gas away from galaxies, and other processes. Surprisingly, our study showed that such galaxies can be found also in the poorest groups in the lowest density regions around the supercluster where such processes cannot work. This intriguing result shows that environment affects the star formation properties of galaxies at a wide range of scales.


Our study suggest that the richest galaxy cluster in the A2142 supercluster passed turnaround and started to collapse approximately 3 - 4 billion years ago. our finding that galaxies with very old stellar populations can be found not only in the central parts of galaxy clusters and groups, but also in the poorest groups in the lowest density regions around the supercluster is very interesting and needs future analysis.

Dr Maret Einasto
Tartu Observatory

Read the Original

This page is a summary of: Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SCl A2142 cocoon, Astronomy and Astrophysics, September 2020, EDP Sciences,
DOI: 10.1051/0004-6361/202037982.
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