Quenching in Cosmic Sheets: Tracing the Impact of Large Scale Structure Collapse on the Evolution of Dwarf Galaxies

TL;DR

This study shows that large-scale structure collapse in the early universe can heat the intergalactic medium, leading to environmental quenching of dwarf galaxies even before they fall into larger systems.

Contribution

It introduces the concept that cosmic web collapse can pre-process dwarf galaxies, causing quenching independently of galaxy groups or clusters.

Findings

Shock-heated cosmic sheets can quench central dwarf galaxies.

Massive dwarfs experience reduced star formation and gas accretion due to shocks.

Pre-processing by large-scale structure collapse explains isolated quenched dwarfs.

Abstract

Dwarf galaxies are thought to quench primarily due to environmental processes most typically occurring in galaxy groups and clusters or around single, massive galaxies. However, at earlier epochs, ($5 < z < 2$), the collapse of large scale structure (forming Zel'dovich sheets and subsequently filaments of the cosmic web) can produce volume-filling accretion shocks which elevate large swaths of the intergalactic medium (IGM) in these structures to a hot ($T>10^6$ K) phase. We study the impact of such an event on the evolution of central dwarf galaxies ($5.5 < \log M_* < 8.5$) in the field using a spatially large, high resolution cosmological zoom simulation which covers the cosmic web environment between two protoclusters. We find that the shock-heated sheet acts as an environmental quencher much like clusters and filaments at lower redshift, creating a population of quenched, central dwarf galaxies. Even massive dwarfs which do not quench are affected by the shock, with reductions to their sSFR and gas accretion. This process can potentially explain the presence of isolated quenched dwarf galaxies, and represents an avenue of pre-processing, via which quenched satellites of bound systems quench before infall.