Supervoids in the WISE-2MASS catalogue imprinting cold spots in the cosmic microwave background

F. Finelli, J. García-Bellido, A. Kovács, F. Paci, I. Szapudi

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22 Citations (Scopus)

Abstract

The Cold Spot (CS) is a clear feature in the cosmic microwave background (CMB); it could be of primordial origin, or caused by a intervening structure along the line of sight.We identified a large projected underdensity in the recently constructed WISE-2MASS all-sky infrared galaxy catalogue aligned with the CS direction at (l, b) ≈ (209°, -57°). It has an angular size of tens of degrees, and shows a ~20 per cent galaxy underdensity in the centre. Moreover, we find another large underdensity in the projected WISE-2MASS galaxy map at (l, b) ≈ (101°, 46°) (hereafter Draco supervoid), also aligned with a CMB decrement, although less significant than that of the CS direction. Motivated by these findings, we develop spherically symmetric Lemaitre-Tolman-Bondi (LTB) compensated void models to explain the observed CMB decrements with these two underdensities, or 'supervoids'. Within our perturbative treatment of the LTB voids, we find that the integrated Sachs-Wolfe and Riess-Sciama effects due to the Draco supervoid can account for the CMB decrement observed in the same direction. On the contrary, the extremely deep CMB decrement in the CS direction is more difficult to explain by the presence of the CS supervoid only. Nevertheless, the probability of a random alignment between the CS and the corresponding supervoid is disfavoured, and thus its contribution as a secondary anisotropy cannot be neglected. We comment on how the approximations used in this paper, in particular the assumption of spherical symmetry, could change quantitatively our conclusions and might provide a better explanation for the CMB CS.

Original languageEnglish
Pages (from-to)1246-1256
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume455
Issue number2
DOIs
Publication statusPublished - 2016

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Keywords

  • Cosmic background radiation
  • Cosmology: observations
  • Large-scale structure of Universe
  • Surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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