We present the power spectrum of galaxy clusters measured from the new ROSAT-ESO Flux-Limited X-Ray ( REFLEX II ) galaxy cluster catalogue .
This new sample extends the flux limit of the original REFLEX to 1.8 \times 10 ^ { -12 } { erg } { s } ^ { -1 } { cm } ^ { -2 } , yielding a total of 911 clusters with \geq 94 per cent completeness in redshift follow-up .
The analysis of the data is improved by creating a set of 100 REFLEX II-like mock galaxy cluster catalogues built from a suite of large volume \Lambda CDM N -body simulations ( L-BASICC II ) .
The measured power spectrum is in agreement with the predictions from a \Lambda CDM cosmological model .
The measurements show the expected increase in the amplitude of the power spectrum with increasing X-ray luminosity .
On large scales , we show that the shape of the measured power spectrum is compatible with a scale independent bias and provide a model for the amplitude that allows us to connect our measurements with a cosmological model .
By implementing a luminosity-dependent power spectrum estimator , we observe that the power spectrum measured from the REFLEX II sample is weakly affected by flux-selection effects .
The shape of the measured power spectrum is compatible with a featureless power spectrum on scales k > 0.01 h Mpc ^ { -1 } and hence no statistically significant signal of baryonic acoustic oscillations can be detected .
We show that the measured REFLEX II power spectrum displays signatures of non-linear evolution .