Cosmic dust explains why the intensity of the Sunyaev-Zeldovich Effect is independent of Redshift.
Collapsing cluster galaxies are implosions producing extremely energetic electrons at temperatures of about 10^8 K. Astronomers believe CMBR (Cosmic Microwave Background Radiation) photons passing through the collapsing galaxies gain energy by collisions with these electrons and blue-shift by the inverse-Compton effect. Measurement of CMBR in the direction of a cluster of galaxies shows a measurable, but almost imperceptible distortion called the Sunyaev-Zeldovich Effect (SZE).
The SZE shows the 20 to 1000 GHz microwave emission from collapsing cluster galaxies is virtually identical to the CMBR. The SZE spectrum shows a decrease in intensity at frequencies lower than around 218 GHz with an increase in intensity at higher frequencies. Although electrons at 10^8 K emit X-rays, the thermal distortion of the CMBR is only of the order of one-thousandth of a Kelvin in temperature. At a given frequency, the SZE intensity varies in brightness in proportion to the mass distribution within the cluster. The SZE is usually only associated with massive objects such as clusters of galaxies, i.e., a single galaxy has insufficient mass to cause measurable distortions in the SZE.
However, the most remarkable finding is the SZE intensity is independent of redshift Z.