%0 Journal Article %T Constraining primordial non-Gaussianity via a multitracer technique with surveys by Euclid and Square Kilometre Array %A Daisuke Yamauchi %A Keitaro Takahashi %A Masamune Oguri %J Physics %D 2014 %I arXiv %R 10.1103/PhysRevD.90.083520 %X We forecast future constraints on local-type primordial non-Gaussianity parameter $f_{\rm NL}$ with a photometric galaxy survey by Euclid, a continuum galaxy survey by Square Kilometre Array (SKA), and their combination. We derive a general expression for the covariance matrix of the power spectrum estimates of multiple tracers to show how the so-called multitracer technique improves constraints on $f_{\rm NL}$. In particular we clarify the role of the overlap fraction of multiple tracers and the division method of the tracers. Our Fisher matrix analysis indicates that stringent constraints of $\sigma (f_{\rm NL})\lesssim 1$ can be obtained even with a single survey, assuming five mass bins. When Euclid and SKA phase 1 (2) are combined, constraints on $f_{\rm NL}$ are improved to $\sigma (f_{\rm NL})= 0.61~(0.50)$. %U http://arxiv.org/abs/1407.5453v2