eROSITA cluster cosmology forecasts: cluster temperature substructure bias

Abstract

The eROSITA mission will provide the largest sample of galaxy clusters detected in X-ray to date (one hundred thousand expected). This sample will be used to constrain cosmological models by measuring cluster masses. An important mass proxy is the electron temperature of the hot plasma detected in X-rays. We want to understand the detection properties and possible bias in temperatures due to unresolved substructures in the cluster halos. We simulated a large number of galaxy cluster spectra with known temperature substructures and compared the results from analysing eROSITA simulated observations to earlier results from Chandra. We were able to constrain a bias in cluster temperatures and its impact on cluster masses as well as cosmological parameters derived from the survey. We found temperatures in the eROSITA survey to be biased low by about five per cent due to unresolved temperature substructures (compared to emission-weighted average temperatures from the Chandra maps). This bias would have a significant impact on the eROSITA cosmology constraints if not accounted for in the calibration. We isolated the bias effect that substructures in galaxy clusters have on temperature measurements and their impact on derived cosmological parameters in the eROSITA cluster survey.

8 pages, 7 figures, accepted for publication in A&A

References in corpus (4)

• A deeper X-ray study of the core of the Perseus galaxy cluster: the power of sound waves and the distribution of metals and cosmic rays
• Contour binning: a new technique for spatially-resolved X-ray spectroscopy applied to Cassiopeia A
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• Scaling relations for dark matter core density and radius from Chandra X-ray cluster sample
• Galaxy clusters, cosmic chronometers and the Einstein equivalence principle
• Tidal virialization of dark matter haloes with clustering dark energy