Properties of high redshift clusters are a fundamental source of information
for cosmology. It has been shown by Oukbir and Blanchard (1997) that the
combined knowledge of the redshift distribution of X-ray clusters of galaxies
and the luminosity-temperature correlation, LXββTXβ, provides a powerful test
of the mean density of the Universe. In this paper, we address the question of
the possible evolution of this relation from an observational point of view and
its cosmological significance. We introduce a new indicator in order to measure
the evolution of the X-ray luminosity-temperature relation with redshift and
take advantage of the recent availability of temperature information for a
significant number of high and intermediate redshift X-ray clusters of
galaxies. From our analysis, we find a slightly positive evolution in the
LXββTXβ relation. This implies a high value of the density parameter of
0.85Β±0.2. However, because the selection of clusters included inour sample
is unknown, this can be considered only as a tentative result. A
well-controlled X-ray selected survey would provide a more robust answer. XMM
will be ideal for such a program.Comment: 10 pages, LaTeX, 4 figures,5 tables, accepted by A&
