The Dependence of Galaxy Properties on the Underlying 3D Matter Density Field at 2.0<z<2.5
We study the environmental effect of galaxy evolution as a function of the underlying 3D dark matter density for the first time at $z=2-2.5$, in which the underlying matter density is reconstructed from galaxy and Ly$\alpha$ forest spectroscopy through dynamical forward modeling techniques. Utilizing these maps, we investigate the dependence of the star formation activities and galaxy types (mergers, submillimeter galaxies, active galactic nuclei, and quiescent galaxies) on the matter overdensity $\Delta$ and stellar mass. For the first time, we are able to probe underdense regions ($\Delta <1$) in addition to overdensities. We find that star formation activity generally depend on the stellar mass, not the matter density, except for high-mass galaxies ($M_*\geq10^{10.5}$ M$_\odot$) which show a drop in star formation activities by a factor of more than $30$ if they reside in high density regions with $\Delta\geq4-6$. We also find: (1) an absence of mergers and submillimeter galaxies in higher-density regions but otherwise no trend across lower-density bins, (2) the increase of active galactic nuclei and quiescent galaxy prevalence as a function of matter density, and (3) the increase of all aforementioned categories with the stellar mass. These results indicate that mass is the main driver of galaxy evolution. Nonetheless, we also find evidence for environmental quenching, particularly for high-mass galaxies in high-density environments. Our novel approach directly using reconstructed dark matter density maps demonstrates the new capability of the environmental effect studies in galaxy evolution at higher redshift.