Finding bright z ≥ 6.6 Ly α emitters with lensing: prospects for Euclid

We model the z >= 6.6 Ly alpha luminosity function to estimate the number of lensed high-z Ly alpha emitters that may be detected by the Euclid Deep Survey. To span the whole range of possible predictions, we exploit two Ly alpha luminosity function models and two strong gravitational lensing models from the literature. We show that the planned Euclid Deep Survey observing 40 deg(2) 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 similar to 0.85 and similar to 1.82 deg(-2) lensed Ly alpha emitters at z >= 6.6 depending on the adopted Ly alpha luminosity function and strong gravitational lensing model. The obvious [O II], [O III] and H beta contaminants of the Ly alpha 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 alpha emitters. By combining Euclid and the SKA, we will thus be able to identify, for the first time, a sample of similar to 34 to similar to 73 lensed Ly alpha emitters at z >= 6.6.