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Measuring Statistical isotropy of the CMB anisotropy

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arxiv astro-ph/0308001 v2 pith:2FUXNTJC submitted 2003-07-31 astro-ph gr-qchep-th

classification astro-phgr-qchep-th
keywords kappacosmicstatisticalviolationanisotropyisotropybiasmeasuring
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abstract

The statistical expectation values of the temperature fluctuations of cosmic microwave background (CMB) are assumed to be preserved under rotations of the sky. This assumption of {\em statistical isotropy} (SI) of the CMB anisotropy should be observationally verified since detection of violation of SI could have profound implications for cosmology. We propose a set of measures, $\kappa_\ell$ ($\ell=1,2,3, ...$) for detecting violation of statistical isotropy in an observed CMB anisotropy sky map indicated by non zero $\kappa_\ell$. We define an estimator for the $\kappa_\ell$ spectrum and analytically compute its cosmic bias and cosmic variance. The results match those obtained by measuring $\kappa_\ell$ using simulated sky maps. Non-zero (bias corrected) $\kappa_\ell$ larger than the SI cosmic variance will imply violation of SI. The SI measure proposed in this paper is an appropriate statistics to investigate preliminary indication of SI violation in the recently released WMAP data.

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Cited by 4 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Testing Statistical Isotropy on the Sphere with Minkowski Tensors

    astro-ph.CO 2026-07 conditional novelty 7.0 of 10

    Connected-patch orientation correlations ξ±(θ,ν) give a coordinate-independent test of statistical isotropy on the sphere and separate global from local alignment in sheared random fields, while dipole modulation leav...

  2. Spin-1 Ultralight Dark Matter under Cosmological Scrutiny: Mass Constraints from CMB and Distance Probes

    astro-ph.CO 2026-07 conditional novelty 6.0 of 10

    Cosmological data place a lower bound near 10⁻²⁴ eV on spin-1 ultralight dark matter and predict a CMB anisotropy signature that may be detectable when the vector field is a minor dark-matter component.

  3. CMB sky for an off-center observer in a local void I: framework for forecasts

    astro-ph.CO 2019-08 conditional novelty 6.0 of 10

    An off-center observer in an LTB void would see off-diagonal CMB correlations; the paper develops a Fisher forecast framework and finds S/N > 10 for two illustrative void models with Planck.

  4. Probing the Cosmological Principle with weak lensing shear

    astro-ph.CO 2024-11 conditional novelty 4.0 of 10

    A Euclid-like weak lensing survey could detect the E-B shear cross-correlation produced by late-time anisotropic expansion, yielding a new probe of the Cosmological Principle.

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