The bright end of the z ~ 7 UV luminosity function from a wide and deep HAWK-I survey

Aims. We perform a deep search for galaxies in the redshift range 6: 5�z�7: 5, to measure the evolution of the number density of luminous galaxies in this redshift range and derive useful constraints on the evolution of their luminosity function. Methods. We present here the second half of an ESO Large Programme, which exploits the unique combination of area and sensitivity provided in the near‐IR by the camera Hawk-I at the VLT. We have obtained�30 observing hours with Hawk-I in the Y-band of two high galactic latitude fields. We combined the Y-band data with deep J and K Hawk-I observations, and with FORS1/FORS2 U, B, V, R, I, and Z observations to select z-drop galaxies having Z− Y> 1, no optical detection and flat Y− J and Y− K colour terms. Results. We detect 8 high-quality candidates in the magnitude range Y = 25: 5− 26: 5 that we add to the z-drop candidates selected in two Hawk-I pointings over the GOODS-South field. We use thi s full sample of 15 objects found in�161 arcmin 2 of our survey to constrain the average physical properties and the evolut ion of the number density of z �7 LBGs. A stacking analysis yields a