2017MNRAS.470.5007M

We model the z >= 6.6 Ly α luminosity function to estimate the number of lensed high-z Ly α emitters that may be detected by the Euclid Deep Survey. To span the whole range of possible predictions, we exploit two Ly α luminosity function models and two strong gravitational lensing models from the literature. We show that the planned Euclid Deep Survey observing 40 deg² over the 920-1850 nm wavelength range down to a flux limit of F_lim = 5 x 10^–17 erg s^–1 cm^–2 will enable us to find between ∼0.85 and ∼1.82 deg^–2 lensed Ly α emitters at z >= 6.6 depending on the adopted Ly α luminosity function and strong gravitational lensing model. The obvious [O II], [O III] and H β contaminants of the Ly α lensed population will be identified with the help of Euclid's spectral resolving power, while the Square Kilometre Array (SKA) will enable the identification of the interloper population of H α emitters. By combining Euclid and the SKA, we will thus be able to identify, for the first time, a sample of ∼34 to ∼73 lensed Ly α emitters at z >= 6.6.