Disturbed galaxy clusters are more abundant in an X-ray volume-limited sample

Understand

We present first strong observational evidence that the X-ray cool-core bias or the apparent bias in the abundance of relaxed clusters is absent in our REFLEX volume-limited sample (ReVols).

• We show that these previously observed biases are due to the survey selection method such as for an flux-limited survey, and are not due to the inherent nature of X-ray selection.
• We also find that the X-ray luminosity distributions of clusters for the relaxed and for the disturbed clusters are distinct and a displacement of approximately 60 per cent is required to match two distributions.
• Our results suggest that to achieve more precise scaling relation one may need to take the morphology of clusters and their fractional abundance into account.