2013/11/18 by Craig J. Copi, Dragan Huterer, Dominik J. Schwarz +1 · 1 voice · 93 citations
Physics and Astronomy · #Anisotropy #Astronomy #Astrophysics #CMB cold spot #Cosmic background radiation #Cosmic microwave background #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Physics #Planck #Quantum mechanics #Radio Astronomy Observations and Technology #astro-ph.CO
paper · pdf · doi:10.1093/mnras/stv501
published in Monthly Notices of the Royal Astronomical Society 449(4), 3458-3470 (Oxford University Press) · 12 pages, 6 figures, submitted to MNRAS, v2: Clarification comment added, other minor improvements, v3: Updates to match published version, this includes a discussion of the Planck reported Doppler quadrupole correction of the cleaned, full-sky maps
arxiv published 2013/11/18 · openalex publication_date 2015/04/09 · arxiv created 2015/06/03 · arxiv updated 2015/06/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We revisit the alignments of the largest structures observed in the cosmic microwave background (CMB) using the seven and nine-year Wilkinson Microwave Anisotropy Probe (WMAP) and first-year Planck data releases. The observed alignments – the quadrupole with the octopole and their joint alignment with the direction of our motion with respect to the CMB (the dipole direction) and the geometry of the Solar system (defined by the Ecliptic plane) – are generally in good agreement with results from the previous WMAP data releases. However, a closer look at full-sky data on the largest scales reveals discrepancies between the earlier WMAP data releases (three to seven-year) and the final, nine-year release. There are also discrepancies between all the WMAP data releases and the first-year Planck release. Nevertheless, both the WMAP and Planck data confirm the alignments of the largest observable CMB modes in the Universe. In particular, the p-values for the mutual alignment between the quadrupole and octopole, and the alignment of the plane defined by the two with the dipole direction, are both at the greater than 3-sigma level for all three Planck maps studied. We also calculate conditional statistics on the various alignments and find that it is currently difficult to unambiguously identify a leading anomaly that causes the others or even to distinguish correlation from causation.