  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.
