http://arxiv.org/abs/2109.14297
We report the first evidence of intrinsic alignment (IA) of red galaxies at $z>1$. We measure the gravitational shear-intrinsic ellipticity (GI) cross-correlation function at $z\sim1.3$ using galaxy positions from the FastSound spectroscopic survey and galaxy shapes from Canada-Hawaii-France telescope lensing survey data. Adopting the non-linear alignment model, we obtain a $2.4\sigma$ level detection of the IA amplitude, $A^{\rm LA}=27.48_{-11.54}^{+11.53}$, larger than the value extrapolated from the constraints obtained at lower redshifts. Our measured IA is translated into a $\sim 20\%$ contamination to the weak lensing power spectrum for the red galaxies. This marginal detection of IA for red galaxies at $z>1$ motivates the continuing investigation of the nature of IA for weak lensing studies. Furthermore, our result provides the first step to utilize IA measurements in future high-$z$ surveys as a cosmological probe, complementary to galaxy clustering and lensing.
M. Tonegawa and T. Okumura
Thu, 30 Sep 21
29/82
Comments: 7 pages, 3 figures
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