We compute the redshift space power spectrum of two X-ray cluster samples : the X-ray Brightest Abell Cluster Sample ( XBACS ) and the Brightest Cluster Sample ( BCS ) using the method developed by Feldman , Kaiser & Peacock .
The power spectrums derived for these samples are in agreement with determinations of other optical and X-ray cluster samples .
For XBACS we find the largest power spectrum amplitude expected given the high richness of this sample ( R \geq 2 ) .
In the range 0.05 h { { Mpc ^ { -1 } } } < k < 0.4 h { { Mpc ^ { -1 } } } the power spectrum shows a power law behavior P ( k ) \propto k ^ { n } with an index n \simeq - 1.2 .
In a similar range 0.04 h { { Mpc ^ { -1 } } } < k < 0.3 h { { Mpc ^ { -1 } } } BCS power spectrum has a smaller amplitude with index n \simeq - 1.0 .
We do not find significant evidence for a peak at k \simeq 0.05 h { { Mpc ^ { -1 } } } suggesting that claims such of feature detections in some cluster samples could relay on artificial inhomogeneities of the data .
We compare our results with power spectrum predictions derived by Moscardini et al .
within current cosmological models ( LCDM and OCDM ) .
For XBACS we find that both models underestimate the amplitude of the power spectrum but for BCS there is reasonably good agreement at k \mathrel { \hbox { \hbox to 0.0 pt { \hbox { \lower 4.0 pt \hbox { $ \sim$ } } } \hbox { $ > $ } } } 0. % 03 h { { Mpc ^ { -1 } } } for both models .