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Session: Extragalactic Astronomy and Astrophysics

Name: Dr. Konstantinos Migkas (Leiden University)
Coauthors: No coauthors were included.
Type: Oral
Title: Cross-calibration of eROSITA cluster temperatures with other X-ray telescopes
Abstract:

Galaxy cluster gas temperatures are a crucial part of cluster astrophysics and cosmology. They are an excellent proxy of total cluster mass, while they are also crucial for tests of cosmic isotropy with clusters. However, it has been shown that cluster temperature measurements can significantly vary between different X-ray telescopes. As those temperatures determine our view on galaxy cluster physics, mass estimates, and cosmological parameters, it is of utter importance to cross-calibrate X-ray instruments to avoid systematic biases. In this work, we present for the first time the cross-calibration of eROSITA against XMM-Newton and Chandra, using the first all-sky survey of eROSITA. We measured and compared core and core-excised temperatures of 51 common clusters between eROSITA and XMM-Newton and 127 clusters between eROSITA and Chandra, using the same spectral extraction regions. The comparison takes place in the full, soft, and hard X-ray bands, to better understand the origin of any discrepancies. Overall, significant deviations between the temperature measurements are observed across all instruments. For the full X-ray band and average-sided clusters, eROSITA measures 10% and 25% lower temperatures than XMM-Newton and Chandra respectively. The agreement is better for the soft band and/or galaxy groups and worse for the hard band and/or massive clusters. The results of this work will be essential for future cluster studies that wish to combine eROSITA data with other X-ray instruments.