North-South non-Gaussian asymmetry in PLANCK CMB maps

Abstract

We report the results of a statistical analysis performed with the four foreground-cleaned Planck maps by means of a suitably defined {\it local-variance} estimator. Our analysis shows a clear dipolar structure in Planck's {\it variance map} pointing in the direction $(l,b)\simeq (220^{\circ },-32^{\circ })$, thus consistent with the North-South asymmetry phenomenon. Surprisingly, and contrary to previous findings, removing the CMB quadrupole and octopole makes the asymmetry stronger. Our results show a maximal statistical significance, of $98.1\%$ CL, in the scales ranging from $\ell =4$ to $\ell =500$. Additionally, through exhaustive analyses of the four foreground-cleaned and individual frequency Planck maps, we find unlikely that residual foregrounds could be causing this dipole variance asymmetry. Moreover, we find that the dipole gets lower amplitudes for larger masks, evidencing that most of the contribution to the variance dipole comes from a region near the galactic plane. Finally, our results are robust against different foreground cleaning procedures, different Planck masks, pixelization parameters, and the addition of inhomogeneous real noise.

19 pages, 13 figures. Re-submitted to match published version

References in corpus (30)

• Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
• Primordial Non-Gaussianities from Inflation Models
• Inflationary Cosmology
• A full sky, low foreground, high resolution CMB map from WMAP
• Hemispherical power asymmetry in the three-year Wilkinson Microwave Anisotropy Probe sky maps
• The Uncorrelated Universe: Statistical Anisotropy and the Vanishing Angular Correlation Function in WMAP Years 1-3
• Power asymmetry in WMAP and Planck temperature sky maps as measured by a local variance estimator
• Anisotropic Dark Energy: Dynamics of Background and Perturbations
• J-PAS: The Javalambre-Physics of the Accelerated Universe Astrophysical Survey
• The Axis of Evil revisited
• Secondary anisotropies of the CMB
• CMB Temperature Anisotropy from Broken Spatial Isotropy due to an Homogeneous Cosmological Magnetic Field
• New constraints on Parity Symmetry from a re-analysis of the WMAP-7 low resolution power spectra
• On the CMB large-scales angular correlations
• Alignment tests for low CMB multipoles
• A low CMB variance in the WMAP data
• Testing Isotropy of Cosmic Microwave Background Radiation
• Anomalous CMB north-south asymmetry
• Planck CMB Anomalies: Astrophysical and Cosmological Secondary Effects and the Curse of Masking
• Power Asymmetries in the Cosmic Microwave Background Temperature and Polarization patterns
• Non-Gaussianity as a Probe of the Physics of the Primordial Universe and the Astrophysics of the Low Redshift Universe
• Component separation with flexible models. Application to the separation of astrophysical emissions
• Non-Gaussianity analysis on local morphological measures of WMAP data
• Searching for non-Gaussianity in the WMAP data
• Can residuals of the Solar system foreground explain low multipole anomalies of the CMB ?
• Steerable wavelet analysis of CMB structures alignment
• The Parity Odd Universe, Dark Energy and QCD
• Angular-planar CMB power spectrum
• Impact of Instrumental Systematics on the CMB Bispectrum
• Identification of galaxy clusters in cosmic microwave background maps using the Sunyaev-Zel'dovich effect

Cited by in corpus (8)

• Challenges for $\Lambda$CDM: An update
• On the significance of power asymmetries in Planck CMB data at all scales
• Cosmic homogeneity: a spectroscopic and model-independent measurement
• The homogeneity scale and the growth rate of cosmic structures
• Isotropy statistics of CMB hot and cold spots
• Excess of lensing amplitude in the Planck CMB power spectrum
• Detection of Dipole Modulation in CMB Temperature Anisotropy Maps from WMAP and Planck using Artificial Intelligence
• Viability of general relativity and modified gravity cosmologies using high-redshift cosmic probes