Correlation between H <i>α</i> Emitters and Their Cosmic Web Environment at <i>z</i>  ∼ 1

Abstract Future near-infrared spectroscopic galaxy surveys will target high-redshift emission-line galaxies (ELGs) to test cosmological models. Deriving optimal constraints from ELG clustering hinges on a robust understanding of their environmental dependence. Using the TNG300-1 simulation, we explore the correlation between properties of H α emitters and their environment anisotropy rather than traditional density-based measures. Our galactic H α emission model includes contributions from the warm interstellar medium. The environment anisotropy and type are assigned using a halo-mass-dependent smoothing scale. We find that most luminous H α emitters ( L H α &gt; 10 42 erg s −1 ) reside in filaments and knots. More generally, H α emitters are more biased in strongly anisotropic environments. While correlations with galactic properties are found to be weak, they are statistically significant for host halo masses M ≲ 10 12 M ⊙ h −1 . Our analysis motivates further investigation into how environmental anisotropy influences galaxy evolution, and highlights the potential for leveraging these effects in the analyses of upcoming cosmological surveys.