How do our voids compare with other accounts in the literature?

Comparing our catalog to the known voids that have been historically identified by astronomers with observational methods is a non-trivial task: voids not only subtend great angles in the sky, but they are also interconnected, making their centers and boundaries not well defined. We carry out a qualitative comparison with previous works.

Cosmicflows-3

Tully et al. (2019) have characterized the shape and interplay of voids, by analyzing the velocities of the surrounding galaxies to reconstruct the underlying density field, using the Cosmicflows-3 dataset. We compare with the 25 local minima they identify, classified as part of the Local void, the Hercules void, the Sculptor void, and the Eridanus void.

The first two columns define the underdense regions identified by the authors, while columns 3-5 indicate their coordinates in supergalactic coordinates. Columns 6-8 are the result of the transformation in our coordinate system, with the observer located at $[340.5, 340.5, 340.5] \, h^{−1} \, \text{Mpc}$, the xy plane corresponding to the equatorial plane, and the $\hat{z}$ axis pointing to the equatorial North Pole. The last two columns report the best matching void of our catalog and the value of the Voronoi cloud in that location. The void names link to a visual representation of the comparisons, with points falling inside our Voronoi clouds marked in red.

$\text{Void}$ $\text{Description}$ $ \text{SGX} \ [\text{km s}^{-1}]$ $\text{SGY} \ [\text{km s}^{-1}]$ $\text{SGZ} \ [\text{km s}^{-1}]$ $x \ [h^{-1} \, \text{Mpc}]$ $y \ [h^{-1} \, \text{Mpc}]$ $z \ [h^{-1} \, \text{Mpc}]$ $\text{Match}$ $\text{Voronoi overlap}$
Local Lacerta-2.4 1650 -700 1650 356.8 331.4 356.2 $\sim$#75 0.335 < 0.37
Local Andromeda-2.3 2100 -700 -300 354.0 351.1 354.8 #75 0.532 > 0.37
Local Aquila-0.8 -200 -200 700 343.1 333.5 339.8 #10 0.581 > 0.37
Local UMi-3.7 3100 1700 1200 339.6 338.2 377.8 None 0.087 < 0.37
Hercules Hercules-6.5 -1200 4000 5000 311.5 285.8 360.8 None 0.041 < 0.37
Hercules Boötes-8 -200 6400 5000 293.7 286.9 379.8 None 0.032 < 0.37
Hercules UMa-4.3 2100 3500 -1200 314.2 355.5 370.4 #96 0.756 > 0.37
Hercules Sextans-7.4 -3100 4000 -5400 280.6 376.6 316.3 #57 0.431 > 0.37
Hercules Leo-5.2; Coma -200 5000 -1700 290.9 350.9 355.6 #28 0.581 > 0.37
Hercules Serpens Caput-3.9 -1200 3100 2100 313.0 313.8 349.1 #62 0.529 > 0.37
Hercules Leo-7.5 1200 5400 -5000 285.0 386.2 360.5 None 0.076 < 0.37
Hercules UMa-5.8 3500 4500 700 314.8 341.6 391.9 None 0.161 < 0.37
Sculptor Reticulum-2.6 -1200 -1700 -1700 347.4 353.9 318.3 #38 0.966 > 0.37
Sculptor Capricornus-3.7 -1700 -2100 2600 358.9 312.4 323.9 #10 0.876 > 0.37
Sculptor Pisces-3.1 1700 -2600 200 370.7 346.9 344.5 #75 0.464 > 0.37
Sculptor Pegasus-6.2 1700 -4500 4000 396.5 313.2 346.7 None 0.083 < 0.37
Sculptor Telescopium-8.1 -6400 -4000 3000 359.3 294.4 276.3 #32 0.666 > 0.37
Sculptor Pisces-3.4 2600 -2100 300 369.8 348.6 354.7 #75 0.808 > 0.37
Sculptor Pisces Austrinus-6.1 -1200 -5400 2600 390.5 317.3 314.0 #18 0.43 > 0.37
Sculptor Pavo-6.1 -4500 -4100 700 362.1 322.5 286.0 #32 0.53 > 0.37
Sculptor Sculptor-4.6 -700 -4500 700 379.9 335.9 317.1 #18 0.812 > 0.37
Eridanus Puppis-6.2 -3100 -2100 -5000 336.3 378.7 291.2 #42 0.796 > 0.37
Eridanus Canis Major-4.6 -200 -700 -4500 335.7 382.6 323.6 #8 0.687 > 0.37
Eridanus Cetus-7.8 1100 -7400 -2200 406.1 371.9 312.3 None 0.021 < 0.37
Eridanus Chamaeleon-7.4 -6000 -2600 -3600 333.1 356.2 267.9 #73 0.922 > 0.37

The Local Void

The Local Void is hard to characterize, as it partially lies behind the galactic plane and subtends a big portion of the sky due to its vicinity. Different works define different positions and size: we compare with a few accounts in the literature. The ranges defined in these works partially overlap with our voids, as shown in the last column.

$\text{Void Name}$ $\text{Reference}$ $ \alpha $ $\delta \, [^\circ]$ $\text{Center}$ $\text{Size along los}$ $\text{Void Match}$ $\text{3D shape}$
Local Void Nakanishi et al. (1997) $\sim 20^\text{h}40^\text{m}$ $\sim 16^\circ$ $\sim 2 \ 500 \ \text{km s}^{-1}$ $\sim 2 \ 500 \ \text{km s}^{-1}$ Void #10 Full Cloud
Local Void Karachentsev et al. (2002) $18^\text{h}38^\text{m}$ $18^\circ$ $\sim 800 \ \text{ km s}^{-1}$ $\sim 1 \ 500 \ \text{km s}^{-1}$ Void #10 Full Cloud
Northern Local Void Einasto et al. (1994) $256.1^\circ$ $-4.8^\circ$ $61\,h^{-1} \, \text{Mpc}$ $104\,h^{-1} \, \text{Mpc}$ Voids #10,83 Full Cloud

Other voids

We find a good qualitative match with other voids that have been cited in the literature. The coordinates are either determined from the corresponding constellations or foreground object, or by an explicit definition by the authors.

$\text{Void Name}$ $\text{Reference}$ $ \alpha \, [\mathrm{hms}]$ $\delta \, [^\circ]$ $ z \, \text{range} \, [\text{km s}^{-1}]$ $\text{Void Match}$ $\text{3D shape}$
Coma/A1367 Void Kirshner et al. (1981) $ \sim 12.4^\text{h}$ $\sim 25^\circ $ $5 \ 000 - 6 \ 200$ Void #45 Full Cloud
Boötes Void Kirshner et al. (1981) $\sim 14^\text{h}40^\text{m}$ $\sim 30^\circ$ $12 \ 000 - 18 \ 000$ Void #88 Full Cloud
Pisces Void Kirshner et al. (1981) $\sim 1^\text{h}$ $\sim 15^\circ$ $6 \ 500 - 10 \ 000 $ Void #15 Full Cloud
Hydra Void Willmer et al. (1995) $11^\text{h}$ $-30^\circ$ $4 \ 500 - 6 \ 000 $ Void #57 Full Cloud
Leo Void Willmer et al. (1995) $11^\text{h}30^\text{m}$ $0^\circ < \delta < 10^\circ$ $2 \ 500 - 5 \ 500$ Void #28 Full Cloud