The Quenching Mechanisms of Field Dwarf Galaxies

TL;DR

This study uses the TNG50 simulation to explore how isolated dwarf galaxies stop forming stars, identifying environmental effects and strong gas outflows driven by stellar feedback as key mechanisms.

Contribution

It reveals a new quenching channel in isolated dwarfs caused by stellar feedback-driven gas outflows, supplementing known environmental effects.

Findings

Identifies a population of quenched isolated dwarfs in TNG50.

Finds gas outflows driven by stellar feedback prevent star formation.

Shows outflows are prevalent in low-mass, high-gas-fraction dwarfs.

Abstract

Isolated dwarf galaxies are intrinsically faint and difficult to detect. The limited sample size makes it challenging to observationally constrain the physical mechanisms that quench their star formation. To disentangle the quenching mechanisms of isolated dwarfs, we identify a non-negligible population of such galaxies in the TNG50 simulation. In addition to the previously discovered ``backsplash" galaxies that were quenched by environmental effects when they were once satellites in more massive halos, we find another primary quenching channel in a population of galaxies whose star formation is suppressed by excessively strong gas outflows that prevent the gas from cooling and collapsing to form stars. We further demonstrate that these outflows are highly likely driven by stellar feedback and predominantly occur in high-gas-fraction dwarfs, which within our studied stellar mass range ($10^7$--$10^{9.5},M_\odot$) are always located toward the low-mass end.