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Abstract We examine the quenching characteristics of 328 isolated dwarf galaxies within theRomulus25cosmological hydrodynamic simulation. Using mock-observation methods, we identify isolated dwarf galaxies with quenched star formation and make direct comparisons to the quenched fraction in the NASA Sloan Atlas (NSA). Similar to other cosmological simulations, we find a population of quenched, isolated dwarf galaxies belowMstar< 109M⊙not detected within the NSA. We find that the presence of massive black holes (MBHs) inRomulus25is largely responsible for the quenched, isolated dwarfs, while isolated dwarfs without an MBH are consistent with quiescent fractions observed in the field. Quenching occurs betweenz= 0.5–1, during which the available supply of star-forming gas is heated or evacuated by MBH feedback. Mergers or interactions seem to play little to no role in triggering the MBH feedback. At low stellar masses,Mstar≲ 109.3M⊙, quenching proceeds across several Gyr as the MBH slowly heats up gas in the central regions. At higher stellar masses,Mstar≳ 109.3M⊙, quenching occurs rapidly within 1 Gyr, with the MBH evacuating gas from the central few kpc of the galaxy and driving it to the outskirts of the halo. Our results indicate the possibility of substantial star formation suppression via MBH feedback within dwarf galaxies in the field. On the other hand, the apparent overquenching of dwarf galaxies due to MBH suggests that higher-resolution and/or better modeling is required for MBHs in dwarfs, and quenched fractions offer the opportunity to constrain current models.
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This content will become publicly available on May 15, 2026
The Environmental Quenching Mechanisms of Field Dwarf Galaxies
Abstract Field dwarf galaxies not actively forming stars are relatively rare in the local Universe, but are present in cosmological hydrodynamical simulations. We use the TNG50 simulation to investigate their origin and find that they all result from environmental effects that have removed or reduced their gas content. Quenched field dwarfs consist of either backsplash objects ejected from a massive host or of systems that have lost their gas after crossing overdense regions such as filaments or sheets (“cosmic web stripping”). Quenched fractions rise steeply with decreasing stellar mass, with quenched systems making up roughly ∼15% of all field dwarfs (i.e., excluding satellites) with stellar masses 107 < M⋆/M⊙ < 109. This fraction drops to only ∼1% when a strict isolation criterion that requires no neighbors withM⋆ > 109M⊙within 1.5 Mpc is applied. Of these isolated dwarfs, ∼6% are backsplash, while the other ∼94% have been affected by the cosmic web. Backsplash systems are more deficient in dark matter, have retained less or no gas, and have stopped forming stars earlier than cosmic web-stripped systems. The discovery of deeply isolated dwarf galaxies that were quenched relatively recently would lend observational support to the prediction that the cosmic web is capable of inducing the cessation of star formation in dwarfs.
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- PAR ID:
- 10655247
- Publisher / Repository:
- ADS
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 985
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 86
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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