The detection of the redshifted 21-cm line signal from neutral hydrogen in the intergalactic medium during the epoch of reionization (EoR) is complicated by intense foregrounds such as galactic synchrotron and extragalactic radio galaxies. The 21-cm Lyman a emitter (LAE) crosscorrelation is one of the tools available to reduce foreground effects, because the foreground emission from such radio sources is statistically independent of LAE distribution. There are ongoing LAE surveys by the Subaru hyper suprime-cam (HSC) during the EoR at redshifts z = 6.6 and 7.3. Additionally, the prime focus spectrograph (PFS) will provide precise redshift information of the LAEs discovered by the HSC survey. In this paper, we investigate the detectability of the 21-cm signal with the 21-cm LAE cross-correlation by using our improved reionization simulations. We also focus on the error budget and we evaluate it quantitatively in order to consider a strategy to improve the signal-to-noise ratio. In addition, we explore an expansion of the LAE survey to suggest optimal survey parameters and we show a potential to measure a characteristic size of ionized bubbles via the turnover scale of the cross-power spectrum. As a result, we find that the Murchison Widefield Array has the ability to detect the cross-power spectrum signal on large scales by combining the LAE deep field survey of the HSC. We also show that the sensitivity is improved dramatically at small scales by adding redshift information from the PFS measurements. The Square Kilometre Array has the potential to measure the turnover scale with an accuracy of 6 × 10-3 Mpc-1.
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