Void formation: Does the void-in-cloud process matter?

Hei Yin Jowett Chan, Masashi Chiba, Tomoaki Ishiyama

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


We investigate the basic properties of voids from high-resolution, cosmological N-body simulations of ⋀-dominated cold dark matter (⋀CDM) models, in order to compare with the analytical model of Sheth and van de Weygaert (SvdW) for void statistics. For the subsample of five dark matter simulations in the ⋀CDM cosmology with box sizes ranging from 1000 to 8 h−1 Mpc, we find that the standard void-in-cloud effect is too simplified to explain several properties of identified small voids in simulations. (i) The number density of voids is found to be larger than the prediction of the analytical model up to 2 orders of magnitude below 1 h−1 Mpc scales. The Press-Schechter model with the linear critical threshold of void δv = −2.71, or a naive power law, is found to provide an excellent agreement with the void size function, suggesting that the void-in-cloud effect does not suppress as much voids as predicted by the SvdW model. (ii) We then measured the density and velocity profiles of small voids, and find that they are mostly partially collapsing underdensities, instead of being completely crushed in the standard void-in-cloud scenario. (iii) Finally, we measure the void distributions in four different tidal environments, and find that the void-in-void effect alone can explain the correlation between distribution and environments, whereas the void-in-cloud effect is only weakly influencing the abundance of voids, even in filaments and clusters.

Original languageEnglish
Pages (from-to)2405-2413
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 2019 Dec 1


  • Dark matter
  • Large-scale structure of Universe
  • Methods: numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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