A close examination of cosmic microwave background mirror-parity after Planck

Assaf Ben-David, Ely D. Kovetz

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Previous claims of significant evidence for mirror-parity in the large-scale cosmic microwave background (CMB) data from the Wilkinson Microwave Anisotropy Probe (WMAP) experiment have been recently echoed in the first study of isotropy and statistics of CMBdata from Planck. We revisit these claims with a careful analysis of the latest data available. We construct statistical estimators in both harmonic and pixel space, test them on simulated data with and without mirror-parity symmetry, apply different Galactic masks, and study the dependence of the results on arbitrary choices of free parameters. We confirm that the data exhibit evidence for odd mirror-parity at a significance which reaches as high as ~99 per cent C.L., under some circumstances. However, given the bias exhibited by the pixel-based statistic on a masked sky, its sensitivity to the total power and the dependence of both pixel and harmonic space statistics on the particular form of Galactic masking and other a posteriori choices, we conclude that these results are not in significant tension with the predictions of the concordance cosmological model.

Original languageEnglish
Pages (from-to)2116-2124
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - 1 Dec 2014
Externally publishedYes


  • Cosmic background radiation
  • Methods: data analysis
  • Methods: statistical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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