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Using wide field narrow-band surveys, we provide a new measurement of the$z=6.6$ Lyman-$\alpha$ Emitter (LAE) luminosity function (LF), whichconstraints the bright end for the first time. We use a combination of archivalnarrow-band NB921 data in UDS and new NB921 measurements in SA22 andCOSMOS/UltraVISTA, all observed with the Subaru telescope, with a total area of$\sim 5$ deg$^2$. We exclude lower redshift interlopers by using broad-bandoptical and near-infrared photometry and also exclude three supernovae withdata split over multiple epochs. Combining the UDS and COSMOS samples we findno evolution of the bright end of the Ly$\alpha$ LF between $z=5.7$ and $6.6$,which is supported by spectroscopic follow-up, and conclude that sources with\emph{Himiko}-like luminosity are not as rare as previously thought, withnumber densities of $\sim 1.5\times10^{-5}$ Mpc$^{-3}$. Combined with ourwide-field SA22 measurements, our results indicate a non-Schechter-like brightend of the LF at $z=6.6$ and a different evolution of \emph{observed} faint andbright LAEs. This differential evolution is also seen in the spectroscopicfollow-up of UV selected galaxies and is now also confirmed for Ly$\alpha$emitters, and we argue that it may be an effect of re-ionisation. Using atoy-model, we show that such differential evolution of the LF is expected,since brighter sources are able to ionise their surroundings earlier, such thatLy$\alpha$ photons are able to escape. Our targets are excellent candidates fordetailed follow-up studies and provide the possibility to give a unique view onthe earliest stages in the formation of galaxies and re-ionisation process.

Identification of the brightest Ly\alpha\ emitters at z=6.6: implications for the evolution of the luminosity function in the re-ionisation era