Letter to the Editor

The puzzle of isolated and quenched dwarf galaxies in cosmic voids

¹ Dpto. de Física Teórica y del Cosmos, Facultad de Ciencias (Edificio Mecenas), University of Granada, E-18071 Granada, Spain
² Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, E18071 Granada, Spain
³ Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205 La Laguna, Tenerife, Spain
⁴ Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
⁵ Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 5C2, Canada
⁶ Kapteyn Astronomical Institute, University of Groningen, PO Box 800 9700 AV Groningen, The Netherlands
⁷ Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17 1180 Vienna, Austria
⁸ Département de Physique, de Génie Physique et d’Optique, Université Laval, and Centre de Recherche en Astrophysique du Québec (CRAQ), Québec, QC G1V 0A6, Canada
⁹ Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, E-28040 Madrid, Spain

^⋆ Corresponding author; bidaran@ugr.es

Received: 21 October 2024
Accepted: 12 December 2024

Abstract

We report, for the first time, the detection of a sample of quenched and isolated dwarf galaxies (with 8.9 < log(M_⋆/M_⊙) < 9.5) in the least dense regions of the cosmic web, including voids, filaments, and walls. These dwarfs have no neighboring 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, while also exhibiting a stellar mass assembly very similar to dwarfs in the central regions of galaxy clusters. Furthermore, they have experienced no significant star formation in the past 2 Gyr. Additionally, analyses of r-band images from the Dark Energy Camera Legacy Survey have shown 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, which also contribute to the NSC formation, along with black holes or variations in the conditions around 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.