Low-Density Structures in the Local Universe. II. Nearby Cosmic Voids

TL;DR

This study identifies and characterizes 89 cosmic voids within 40 Mpc, revealing their sizes, distributions, and the properties of dwarf galaxies within these voids, highlighting the large-scale structure of the local universe.

Contribution

It provides a detailed catalog of nearby cosmic voids, their hypervoid structures, and the properties of dwarf galaxies residing in these low-density regions, expanding understanding of local large-scale structure.

Findings

89 voids discovered with diameters 12-24 Mpc

Approximately 30% of the local universe volume is in voids

Dwarf galaxies in voids are mostly late-type with specific star formation and gas properties

Abstract

We present the results of the search for spherical volumes containing no galaxies with luminosities brighter than the Magellanic Clouds in the Local Supercluster and its vicinity. Within a distance of 40 Mpc from us, 89 cosmic voids were discovered with the diameters of 24 to 12 Mpc, containing no galaxies with absolute magnitudes brighter than M_K < -18.4. A list of these voids and the sky distribution maps are given. It was found that 93% of spherical voids overlap, forming three more extended percolated voids (hypervoids). The largest of them, HV1, has 56 initial spherical cells and extends in a horseshoe shape, enveloping the Local Volume and the Virgo cluster. The Local Void (Tully, 1988) in the Hercules-Aquila region is the closest part of the HV1. Another hypervoid, HV2, contains 22 spherical voids in the Eridanus constellation, and the third compact hypervoid (HV3) comprises 6 spherical cells in the Bootes. The total volume of these voids incorporates about 30% of the Local Universe. Among 2906 dwarf galaxies excluded from the original sample (n = 10502) in the search for spherical volumes, only 68 are located in the voids we have discovered. They are characterized by late morphological types (85% are Ir, Im, BCD, Sm), absolute magnitudes M_B ranging from -13.0 to -16.7, moderate star formation rates (log SSFR ~ -10 M_sun/(yr*L_sun) and gas reserves per luminosity unit twice to three times larger than in the other dwarf galaxies located in normal environments. The dwarf population of the voids shows a certain tendency to sit shallow near the surfaces of cosmic voids.