Exposure-corrected 0.5–7 keV Chandra ACIS-I0–3 image of SPT-CL J0217-5014. The source extraction region, centered on the X-ray centroid, is shown by a white circle. The regions used for local background extraction are also indicated. All point sources were excluded from both the source and background regions during imaging and spectral analysis. Credit: arXiv (2025). DOI: 10.48550/arxiv.2512.04689
Astronomers have employed NASA's Chandra spacecraft to perform X-ray observations of a massive galaxy cluster known as SPT-CL J0217-5014. Results of the observational campaign, published December 4 on the arXiv preprint server, yield important insights into the properties and nature of this cluster.
Astronomers have employed NASA's Chandra spacecraft to perform X-ray observations of a massive galaxy cluster known as SPT-CL J0217-5014. Results of the observational campaign, published December 4 on the arXiv preprint server, yield important insights into the properties and nature of this cluster.
Enormous gravitationally-bound structures
Galaxy clusters contain up to thousands of galaxies bound together by gravity. They form through accretion of mass and infall of smaller sub-structures and are the largest known gravitationally-bound structures in the universe. Astronomers perceive galaxy clusters as excellent laboratories for studying galaxy evolution and cosmology.
SPT-CL J0217-5014 is a galaxy cluster at a redshift of 0.53, with a stellar mass of about 300 trillion solar masses, and super-solar iron abundance. Given that very little is known regarding the properties of this cluster, a team of astronomers led by Dan Hu of Masaryk University in Brno, Czech Republic, decided to investigate it with Chandra's Advanced CCD Imaging Spectrometer (ACIS)-I array.
"This study aims to evaluate its chemical and thermodynamic properties with a dedicated Chandra observation," the researchers write.
SPT-CL J0217-5014 is a galaxy cluster at a redshift of 0.53, with a stellar mass of about 300 trillion solar masses, and super-solar iron abundance. Given that very little is known regarding the properties of this cluster, a team of astronomers led by Dan Hu of Masaryk University in Brno, Czech Republic, decided to investigate it with Chandra's Advanced CCD Imaging Spectrometer (ACIS)-I array.
"This study aims to evaluate its chemical and thermodynamic properties with a dedicated Chandra observation," the researchers write.
Disturbed non-cool-core cluster
Chandra imaging revealed that SPT-CL J0217-5014 has a disturbed morphology, characterized by a surface brightness edge at about 330,000 light years
to the west and a tail-like feature extending to the east. Such morphology suggests a disturbed, non-relaxed intracluster medium (ICM).
Furthermore, the collected data indicate that SPT-CL J0217-5014 is a non-cool-core cluster. It turned out that the cluster has a sub-solar abundance, which is consistent with the typical metallicities observed in non-cool-core clusters. The astronomers explained that in such clusters, the dynamical processes could disrupt the cool core and tend to mix the central metal-rich gas with the outer ICM.
The study found that the power ratio and morphology index of SPT-CL J0217-5014 clearly place it in the dynamically disturbed regime. This suggests that the cluster may have experienced a merger event.
Furthermore, the collected data indicate that SPT-CL J0217-5014 is a non-cool-core cluster. It turned out that the cluster has a sub-solar abundance, which is consistent with the typical metallicities observed in non-cool-core clusters. The astronomers explained that in such clusters, the dynamical processes could disrupt the cool core and tend to mix the central metal-rich gas with the outer ICM.
The study found that the power ratio and morphology index of SPT-CL J0217-5014 clearly place it in the dynamically disturbed regime. This suggests that the cluster may have experienced a merger event.
Potential companions of SPT-CL J0217-5014
The observation also resulted in the identification of three potential galaxy clusters near SPT-CL J0217-5014, which received the designations CIG 2, CIG 3, and CIG 4. They have lower mass and are less enriched than SPT-CL J0217-5014. This finding indicates that SPT-CL J0217-5014 is the primary, most massive cluster in this complex and likely sits at a node of the surrounding large-scale structure.
"SPT-CL J0217–5014 likely underwent a relatively energetic, nearly head-on merger that disrupted a pre-existing cool core; ClG 2 and ClG 3 may be lower-mass companions that have merged with or fallen onto the main cluster, while ClG 4 aligns with the extension of the filamentary galaxy distribution, suggesting its association with a broader cosmic web," the authors conclude.
Source: Phys.org/Space News
Written for you by our author: Tomasz Nowakowski, edited by Stephanie Baum, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.
More information: Dan Hu et al, A Chandra view of SPT-CL J0217-5014: a massive galaxy cluster at a cosmic intersection at z=0.53, arXiv (2025). DOI: 10.48550/arxiv.2512.04689
Journal information: arXiv
© 2025 Science X Network
Explore further
X-ray observations reveal dynamic features of galaxy cluster PLCKG287
