The puzzle of isolated and quenched dwarf galaxies in cosmic voids

TL;DR

This study discovers isolated, quenched dwarf galaxies in cosmic voids, showing that internal processes can quench star formation without environmental influence, challenging existing galaxy evolution models.

Contribution

First detection of quenched, isolated dwarf galaxies in cosmic voids, revealing internal quenching mechanisms independent of environment.

Findings

Dwarfs are gas-deprived and have not formed stars in the last 2 Gyr.

These dwarfs host central Nuclear Star Clusters.

Quenched dwarfs exist in the least dense cosmic regions.

Abstract

We report, for the first time, the detection of a sample of quenched and isolated dwarf galaxies (with 8.9 $<$ log(M$_{\rm \star}$/M$_{\rm \odot}$) $<$ 9.5) in the least dense regions of the cosmic web, including voids, filaments, and walls. These dwarfs have no neighbouring galaxy within 1.0~Mpc in projected distance. Based on the full spectral fitting of their central spectra using Sloan Digital Sky Survey data, these galaxies are gas-deprived, exhibit stellar mass assembly very similar to dwarfs in the central regions of galaxy clusters, and have experienced no significant star formation in the past 2 Gyr. Additionally, analysis of r-band images from the Dark Energy Camera Legacy Survey showed that these dwarf galaxies host a central Nuclear Star Cluster (NSC). Detecting quenched, isolated dwarf galaxies in cosmic voids indicates that environmental factors are not the sole drivers of their quenching. Internal mechanisms, such as feedback from in-situ star formation, also contributing to the NSC formation, black holes, or variations in conditions during their formation, offer potential explanations for star formation suppression in these galaxies. These findings highlight the need for a significant revision in our understanding of baryonic physics, particularly concerning the formation and evolution of low-mass galaxies.