The Abell 3158 galaxy cluster inspected by X-ray


Density map of galaxies with members of Abell 3158. Credit: Whelan et al., 2021.

Astronomers from the University of Bonn, Germany and elsewhere, used the eROSITA telescope aboard the Spektrum-Roentgen-Gamma (SRG) mission to perform x-ray observations of a nearby cluster of galaxies known as the name Abell 3158. Results of this observation campaign, published on June 28 on, offer more clues about the properties of this giant structure.

Clusters of galaxies contain up to thousands of galaxies linked together by gravity. They are the largest known gravitational structures in the universe and could serve as excellent laboratories for studying the evolution and cosmology of galaxies.

With a redshift of 0.059 and a characteristic radius of about 23.95 arc minutes, Abell 3158 (or A3158 for short) is a fairly large neighboring cluster of galaxies. Given its relative proximity, Abell 3158 is a good place to examine the faint peripheries where physical and enrichment processes take place, such as minor mergers or the arrival of gas blocks.

A team of astronomers led by Béibhinn Whelan of the University of Bonn, used eROSITA to study the peripheral regions of Abell 3158 in order to shed light on the properties of this object. The study was supplemented by data from ESA’s XMM-Newton satellite.

“We determined 1D temperature, abundance and normalization profiles from the eROSITA and XMM-Newton data, as well as 2D maps of the temperature distribution and metal abundance from the eROSITA data” , the researchers wrote in the document.

The overall temperature of the Abell 3158 was measured at approximately 4.725 keV. Astronomers noted that the temperature, abundance and normalization profiles of eROSITA are consistent with previous studies of this cluster.

The eROSITA data provided more stringent constraints on the metal abundance of Abell 3158 over large radii. According to the article, the normalization profile shows that the values ​​obtained from the XMM-Newton observation are slightly higher than those from eROSITA.

The study found that Abell 3158’s morphology and surface luminosity profile appeared to be regular. However, Abell’s 3158 2D temperature map shows that the cluster does not have a cold core, which is unusual for a cluster with such a surface brightness profile.

In addition, based on the spectroscopic redshifts of 365 members of Abell 3158, the speed dispersion of member galaxies of the cluster has been measured at approximately 1,058 km / s. The total mass of the cluster was calculated to be 1.38 quadrillion solar masses.

The research also identified an extension of gas of about 2.2 million light years westward from the center of Abell 3158. This finding suggests that the cluster is not relaxed but is undergoing fusion activity.

“There is a ∼10 arcmin (∼865 kpc) gas extension west of the cluster center, seen in the bottom logarithmic scale image. We present this gas extension as a new discovery. The irregularities between the different scales would suggest that there could be a sloshing effect occurring in the cluster, further supporting the assertion that the cluster is undergoing merger activity ”, concluded the authors of the article.

Image: Hubble looks at a cluster filled with cosmic clues

More information:
X-ray studies of the Abell 3158 galaxy cluster with eROSITA, arXiv: 2106.14545 [astro-ph.CO]

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Quote: Abell 3158 galaxy cluster X-ray inspected (2021, July 6) retrieved July 6, 2021 from

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