Impact of filaments on galaxy formation in their residing dark matter haloes

TL;DR

This study uses high-resolution hydrodynamical simulations to show that dark matter filaments influence galaxy formation by guiding gas accretion, increasing baryon and stellar fractions, and promoting star formation in filament-residing haloes at high redshifts.

Contribution

It introduces a novel filament identification method and demonstrates the significant role of filaments in gas accretion and galaxy formation in dark matter haloes.

Findings

Gas accretion is highly anisotropic in filament haloes.

Approximately 30% of accreted gas is preprocessed by filaments.

Filament haloes have higher baryon and stellar fractions than field haloes.

Abstract

We make use of a high-resolution zoom-in hydrodynamical simulation to investigate the impact of filaments on galaxy formation in their residing dark matter haloes. A method based on the density field and the Hoshen-Kopelman algorithm is developed to identify filaments. We show that cold and dense gas preprocessed by dark matter filaments can be further accreted into residing individual low-mass haloes in directions along the filaments. Consequently, comparing with field haloes, gas accretion is very anisotropic for filament haloes. About 30 percent of the accreted gas of a residing filament halo was preprocessed by filaments, leading to two different thermal histories for the gas in filament haloes. Filament haloes have higher baryon and stellar fractions when comparing with their field counterparts. Without including stellar feedback, our results suggest that filaments assist gas cooling and enhance star formation in their residing dark matter haloes at high redshifts (i.e. z=4.0 and 2.5).