Alignment and signed-intensity anomalies in WMAP data
arXiv:0704.3736 · doi:10.1111/j.1365-2966.2007.12290.x
Abstract
Significant alignment and signed-intensity anomalies of local features of the cosmic microwave background (CMB) are detected on the three-year WMAP data, through a decomposition of the signal with steerable wavelets on the sphere. Firstly, an alignment analysis identifies two mean preferred planes in the sky, both with normal axes close to the CMB dipole axis. The first plane is defined by the directions toward which local CMB features are anomalously aligned. A mean preferred axis is also identified in this plane, located very close to the ecliptic poles axis. The second plane is defined by the directions anomalously avoided by local CMB features. This alignment anomaly provides further insight on recent results (Wiaux et al. 2006). Secondly, a signed-intensity analysis identifies three mean preferred directions in the southern galactic hemisphere with anomalously high or low temperature of local CMB features: a cold spot essentially identified with a known cold spot (Vielva et al. 2004), a second cold spot lying very close to the southern end of the CMB dipole axis, and a hot spot lying close to the southern end of the ecliptic poles axis. In both analyses, the anomalies are observed at wavelet scales corresponding to angular sizes around 10 degress on the celestial sphere, with global significance levels around 1%. Further investigation reveals that the alignment and signed-intensity anomalies are only very partially related. Instrumental noise, foreground emissions, as well as some form of other systematics, are strongly rejected as possible origins of the detections. An explanation might still be envisaged in terms of a global violation of the isotropy of the Universe, inducing an intrinsic statistical anisotropy of the CMB.
12 pages, 7 figures. Accepted for publication in MNRAS. Small changes made (including the new subsection 3.4) to match the final version
References in corpus (47)
- First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
- Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
- HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
- First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Preliminary Maps and Basic Results
- First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Emission
- Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Temperature Analysis
- Asymmetries in the CMB anisotropy field
- First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Tests of Gaussianity
- The significance of the largest scale CMB fluctuations in WMAP
- The Microwave Anisotropy Probe (MAP) Mission
- Detection of non-Gaussianity in the WMAP 1-year data using spherical wavelets
- The axis of evil
- Is the low-l microwave background cosmic?
- Testing the cosmological principle of isotropy: local power spectrum estimates of the WMAP data
- Multipole Vectors--a new representation of the CMB sky and evidence for statistical anisotropy or non-Gaussianity at 2<=l<=8
- Hemispherical power asymmetry in the three-year Wilkinson Microwave Anisotropy Probe sky maps
- Evidence of vorticity and shear at large angular scales in the WMAP data: a violation of cosmological isotropy?
- The non-Gaussian Cold Spot in the 3-year WMAP data
- Measuring Statistical isotropy of the CMB anisotropy
- Non-Gaussian Signatures in the Temperature Fluctuation Observed by the Wilkinson Microwave Anisotropy Probe
- Testing for Non-Gaussianity in the Wilkinson Microwave Anisotropy Probe Data: Minkowski Functionals and the Length of the Skeleton
- The non-Gaussian Cold Spot in WMAP: significance, morphology and foreground contribution
- Asymmetries in the local curvature of the WMAP data
- The Axis of Evil revisited
- A high-significance detection of non-Gaussianity in the WMAP 1-year data using directional spherical wavelets
- Higher Criticism Statistic: Detecting and Identifying Non-Gaussianity in the WMAP First Year Data
- Wavelets and WMAP non-Gaussianity
- Correspondence principle between spherical and Euclidean wavelets
- Multipole vector anomalies in the first-year WMAP data: a cut-sky analysis
- The N-point correlation functions of the first-year Wilkinson Microwave Anisotropy Probe sky maps
- Statistical Isotropy of the Wilkinson Microwave Anisotropy Probe Data: A Bipolar Power Spectrum Analysis
- Bianchi Type VII_h Models and the WMAP 3-year Data
- Global universe anisotropy probed by the alignment of structures in the cosmic microwave background
- Broken Isotropy from a Linear Modulation of the Primordial Perturbations
- On the Viability of Bianchi Type VIIh Models with Dark Energy
- Mapping the large-scale anisotropy in the WMAP data
- On the CMB large-scales angular correlations
- Alignment tests for low CMB multipoles
- A high-significance detection of non-Gaussianity in the WMAP 3-year data using directional spherical wavelets
- Isotropy of the early universe from CMB anisotropies
- Markov chain Monte Carlo analysis of Bianchi VII_h models
- Polynomial Interpretation of Multipole Vectors
- Fast directional correlation on the sphere with steerable filters
- Examining the Effect of the Map-Making Algorithm on Observed Power Asymmetry in WMAP Data
- Steerable wavelet analysis of CMB structures alignment
- CMB statistical anisotropy, multipole vectors and the influence of the dipole
- Cooling of a New Born Compact Star with QCD Phase Transition
Cited by in corpus (41)
- Planck 2013 results. XXIII. Isotropy and statistics of the CMB
- Planck 2018 results. VII. Isotropy and Statistics of the CMB
- Planck 2015 results. XVI. Isotropy and statistics of the CMB
- CMB Anomalies after Planck
- Cosmic Microwave Background Quadrupole and Ellipsoidal Universe
- Planck pre-launch status: the Planck-LFI programme
- The CMB cold spot: texture, cluster or void?
- New constraints on Parity Symmetry from a re-analysis of the WMAP-7 low resolution power spectra
- Needlet Detection of Features in WMAP CMB Sky and the Impact on Anisotropies and Hemispherical Asymmetries
- A low CMB variance in the WMAP data
- S2LET: A code to perform fast wavelet analysis on the sphere
- Constraints on Primordial Non-Gaussianity from a Needlet Analysis of the WMAP-5 Data
- The axis of evil - a polarization perspective
- Anomalous CMB north-south asymmetry
- Anomalous variance in the WMAP data and Galactic Foreground residuals
- WMAP 5-year constraints on fnl with wavelets
- Can a primordial magnetic field originate large-scale anomalies in WMAP data?
- A Theory of a Spot
- Large scale alignment anomalies of CMB anisotropies: a new test for residuals applied to WMAP 5yr maps
- Non-Gaussianity analysis on local morphological measures of WMAP data
- Non-Gaussian Signatures in the five-year WMAP data as identified with isotropic scaling indices
- Constraints on the non-linear coupling parameter fnl with the Archeops data
- Analysis of non-Gaussian CMB maps based on the N-pdf. Application to WMAP data
- Searching for non-Gaussianity in the WMAP data
- Observation number correlation in WMAP data
- Non-gaussianity in the foreground-reduced CMB maps
- Is the cold spot responsible for the CMB North-South asymmetry?
- Searching for hidden mirror symmetries in CMB fluctuations from WMAP 7 year maps
- CMB polarization as a probe of the anomalous nature of the Cold Spot
- Foreground influence on primordial non-Gaussianity estimates: needlet analysis of WMAP 5-year data
- On the optimality of the spherical Mexican hat wavelet estimator for the primordial non-Gaussianity
- Effect of Foregrounds on the CMBR Multipole Alignment
- The inflationary origin of the Cold Spot anomaly
- Correlation of supernova redshifts with temperature fluctuations of the Cosmic Microwave Background
- Statistics of the excursion sets in models with local primordial non-Gaussianity
- Search for non-Gaussianities in the WMAP data with the Scaling Index Method
- Using CMB polarization to constrain the anomalous nature of the Cold Spot with an incomplete sky-coverage
- Variograms of the Cosmic Microwave Background Temperature Fluctuations: Confirmation of Deviations from Statistical Isotropy
- An overview of the current status of CMB observations
- A Study of Gaussianity in CMB band maps
- Hidden in the background: a local approach to CMB anomalies