The XMM Cluster Survey: Cross-Calibration of eROSITA and XMM using Dark Energy Survey Y3 Galaxy Clusters
Year: 2026
Type: article
Abstract: We present the cross-calibration of the eROSITA and XMM telescopes, using galaxy clusters detected by redMaPPer from the first three years of Dark Energy Survey observations (DESY3RM). We use the X-ray: Generate and Analyse (Xga) Python module to measure eROSITA properties, and validate our methodology using a deep pointed eROSITA CAL-PV observation of A3158, and a sample of 119 clusters from the expanded HIgh FLux Galaxy Cluster Sample (eeHiFLUGCS). Next, we construct a sample of DESY3RM clusters matched to XMM observations analysed by the XMM Cluster Survey (XCS), and to clusters in the first release of the eROSITA All-Sky Survey (eRASS1). This produced a sample of 114 DESY3RM clusters with both XMM and eROSITA detections. Our resulting X-ray temperatures determined from eROSITA were compared to eRASS1 catalogue values, showing consistency between the two analyses. Comparisons between XMM and eROSITA temperatures reveal a systematic offset, with XMM temperatures 28 ± 7% higher on average. Finally, we fit LX, soft-λRM and TX-λRM scaling relations for both eROSITA and XMM using the same cluster sample, finding minimal differences in the LX, soft-λRM relation but a clear normalisation offset in the TX-λRM relation, particularly for the highest richness systems. This study will enable future work combining eROSITA and XMM observatories for DESY3RM clusters.
Institutions: University of Sussex, Universität Innsbruck, Goddard Space Flight Center, High Energy Astrophysics Science Archive Research Center, University of Maryland, Baltimore County, University of the Witwatersrand, University of KwaZulu-Natal, Centre National de la Recherche Scientifique, Université Côte d'Azur, Lagrange Laboratory, Observatoire de la Côte d’Azur, University of Bristol, Michigan State University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Funders: National Aeronautics and Space Administration, National Research Foundation, Eberhard Karls Universität Tübingen, Max-Planck-Gesellschaft, Universität Hamburg, Rheinische Friedrich-Wilhelms-Universität Bonn, Leibniz-Institut für Astrophysik Potsdam, Science and Technology Facilities Council, Leibniz-Gemeinschaft, Russian Academy of Sciences
OpenAlex ID: W7222753335