The WARPS survey - IV. The X-ray luminosity-temperature relation of high-redshift galaxy clusters

We present a measurement of the cluster X-ray luminosity-temperature (L-T) relation out to high redshift (z similar to 0.8). Combined ROSAT PSPC spect ra of 91 galaxy clusters detected in the Wide Angle ROSAT Pointed Survey (W ARPS) are simultaneously fitted in redshift and luminosity bins. The result ing temperature and luminosity measurements of these bins, which occupy a r egion of the high-redshift L-T relation not previously sampled, are compare d with existing measurements at low redshift in order to constrain the evol ution of the L-T relation. We find the best fit to low-redshift (z < 0.2) c luster data, at T > 1 keV, to be L proportional to T3.15 +/- 0.06. Our data are consistent with no evolution in the normalization of the L-T relation up to z similar to 0.8. Combining our results with ASCA measurements taken from the literature, we find eta = 0.19 +/- 0.38 (for Omega(0) = 1, with 1 sigma errors) where L-Bol proportional to (1 + z)T-eta(3.15), or eta = 0.60 +/- 0.38 for Omega(0) = 0.3. This lack of evolution is considered in terms of the entropy-driven evolution of clusters. Further implications for cosm ological constraints are also discussed.