(No) dimming of X-ray clusters beyond z~1 at fixed mass: crude
  redhshifts and masses from raw X-ray and SZ data
  Scaling relations in the LCDM Cosmology predict that for a given mass the
clusters formed at larger redshift are hotter, denser and therefore more
luminous in X-rays than their local z~0 counterparts. This effect overturns the
decrease in the observable X-ray flux so that it does not decrease at z > 1,
similar to the SZ signal. Provided that scaling relations remain valid at
larger redshifts, X-ray surveys will not miss massive clusters at any redshift,
no matter how far they are. At the same time, the difference in scaling with
mass and distance of the observable SZ and X-ray signals from galaxy clusters
at redshifts $z\lesssim 2$ offers a possibility to crudely estimate the
redshift and the mass of a cluster. This might be especially useful for
preselection of massive high-redshift clusters and planning of optical
follow-up for overlapping surveys in X-ray (e.g., by SRG/eRosita) and SZ (e.g.
Planck, SPT and ACT).
