Using data from the eROSITA X-ray telescope aboard the Spektrum-Roentgen-Gamma (SRG) observatory, astronomers have detected a previously unknown supercluster of galaxies.
Color image of the galaxy density map of the supercluster from the Hyper Suprime-Cam on the Subaru Telescope; white circles mark the member clusters detected by eROSITA. Image credit: Ghirardini et al., arXiv: 2012.11607 / Subaru Telescope.
“Cosmic structures evolve hierarchically from high density peaks in the primordial density field and form galaxies, galaxy groups, and clusters of galaxies under the action of gravity,” said Dr. Vittorio Ghirardini from the Max-Planck-Institut für extraterrestrische Physik and his colleagues.
“In the complex large-scale structure formation scenario, these galaxies, groups, and clusters are connected to each other via filamentary structures, called the cosmic web, and form large superclusters.”
The newly-discovered supercluster resides approximately 4 billion light-years away from Earth.
It consists of a chain of eight galaxy clusters: eFEDS J093501.1+005418, eFEDS J093510.7+004910, eFEDS J093513.3+004746, eFEDS J093520.8+003445, eFEDS J093612.6+001651, eFEDS J093546.4-000115, eFEDS J093543.9-000334, and eFEDS J093432.2-002303.
This supercluster stretches for about 1.5 degrees from the north to the south on the plane of the sky, or 88 million light-years considering the physical distance between the furthest clusters in the chain.
Dr. Ghirardini and co-authors discovered this system using the preliminary data from the eROSITA Final Equatorial Depth Survey (eFEDS).
They then examined X-ray, optical, and radio properties of the member clusters.
“We use the X-ray data from eROSITA X-ray telescope, the optical data from the Hyper Suprime-Cam on the Subaru Telescope, and the radio data from the Low-Frequency Array (LOFAR) and the upgraded Giant Metrewave Radio Telescope (uGMRT) to study the multi-wavelength properties of the clusters members of this supercluster and bridge regions between these members,” the astronomers said.
“Our work demonstrates the potential of SRG/eROSITA for not only mapping the large scale structure of the Universe, but also probing the detailed physical properties of their members,” they added.
“Our forecasts show that we will be able to detect 450 superclusters with 3,000 member clusters located in the eROSITA_DE region at the final eROSITA all-sky survey depth, enabling statistical studies of the properties of superclusters and their constituents embedded in the cosmic web.”
The team’s paper will be published in the journal Astronomy & Astrophysics.
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V. Ghirardini et al. 2020. Discovery of a Supercluster in the eROSITA Final Equatorial Depth Survey: X-ray Properties, Radio Halo, and Double Relics. A&A, in press; arXiv: 2012.11607
