  Clusters of galaxies are mainly formed by merging of smaller structures,
according to the standard cosmological scenario. If the mass of a substructure
is >10% of that of a galaxy cluster, the temperature distribution of the
intracluster medium (ICM) in a merging cluster becomes inhomogeneous. Various
methods have been used to derive the two-dimensional projected temperature
distribution of the ICM. However, methods for studying temperature distribution
along the line-of-sight through the cluster were absent. In this paper, we
present the first measurement of the temperature standard deviation along the
line-of-sight, using as a reference case the multifrequency SZ measurements of
the Bullet Cluster. We find that the value of the temperature standard
deviation is high and equals to (10.6+/-3.8) keV in the Bullet Cluster. This
result shows that the temperature distribution in the Bullet Cluster is
strongly inhomogeneous along the line-of-sight and provides a new method for
studying galaxy clusters in depth.
