Intrinsic alignments and spin correlations of [O <scp>ii</scp>] emitters at <i>z</i> = 1.2 and <i>z</i> = 1.5 from the HSC narrow-band survey

Abstract Galaxies are known to be aligned toward specific directions within the large-scale structure. Such alignment signals become important for controlling the systematics of weak-lensing surveys and for constraining galaxy formation and evolution scenarios. We measure the galaxy–ellipticity and ellipticity–ellipticity correlation functions for blue star-forming galaxies at $z=1.19$ and $z=1.47$ that are selected by detecting [O ii] emission lines in narrow-band filters of the Hyper Suprime-Cam on the Subaru Telescope. Assuming that disk galaxies are thin and rotation-supported, we also measure the spin correlation function by estimating spin directions with ellipticities and position angles. Above $1 \,\, h^{-1}\ {\rm Mpc}$, we do not find significant signals for galaxy–ellipticity, ellipticity–ellipticity, or spin correlations at both redshifts. Below $1 \,\, h^{-1}\ {\rm Mpc}$, a weak deviation from zero is seen at $z=1.47$, implying weak spin–filament correlations, but this is not verified by a direct comparison between angles of spins and filaments. The linear alignment model fit yields the amplitude parameter $A_{\rm NLA}=1.38\pm 2.32$ at $z=1.19$ and $0.45\pm 2.09$ at $z=1.47$ ($95\%$ confidence levels). We discuss various observational and physical origins that affect the search for alignments of disk galaxies at high redshifts.