Testing the dipole modulation model in CMBR

Rath, Pranati K.; Jain, Pankaj

doi:10.1088/1475-7516/2013/12/014

Cited by 26 publications

(39 citation statements)

References 28 publications

(92 reference statements)

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“…We have extended the results obtained in a recent paper [53], which showed that the dipole modulation model leads to correlations among spherical harmonic multipoles, a lm and a * l ′ m ′ with m ′ = m and l ′ = l + 1. In that paper we defined a statistic, S H , which provides a measure of this correlation in a chosen multipole range.…”

Section: Discussionsupporting

confidence: 72%

“…Hence in this case we generate a foreground residual free full sky CMB data map at this high resolution. Subsequently we downgrade this map to a lower resolution with N side = 32 after applying appropriate Gaussian beam to smooth the mask boundary [53]. This procedure eliminates any breaks that might be introduced at the boundary due to the random filling procedure.…”

Section: Discussionmentioning

confidence: 99%

“…We first update our results in Ref. [53] for the estimate of the effective value of the dipole modulation parameter,…”

Section: Introductionmentioning

confidence: 99%

“…[53] was extracted using the dipole power of the temperature squared field. In the currrent paper we instead use the statistic, S H (L), which is a much more sensitive probe of A in comparison to temperature square power.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore in Ref. [53], we used COM-MASK-gal-07 for the PLANCK data. In the present paper we use the KQ85 mask for WMAP's nine year ILC map and the more reliable, CMB-union mask for SMICA, also known as the U73 mask.…”

Section: Introductionmentioning

confidence: 99%

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Relating the inhomogeneous power spectrum to the CMB hemispherical anisotropy

2015

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We relate the observed hemispherical anisotropy in the cosmic microwave radiation data to an inhomogeneous power spectrum model. The hemispherical anisotropy can be parameterized in terms of the dipole modulation model. This model leads to correlations between spherical harmonic coefficients corresponding to multipoles, l and l + 1. We extract the l dependence of the dipole modulation amplitude, A, by making a fit to the WMAP and PLANCK CMBR data. We propose an inhomogeneous power spectrum model and show that it also leads to correlations between multipoles, l and l + 1. The model parameters are determined by making a fit to the data. The spectral index of the inhomogeneous power spectrum is found to be consistent with zero.

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Section: Discussionsupporting

confidence: 72%

Section: Discussionmentioning

confidence: 99%

“…We first update our results in Ref. [53] for the estimate of the effective value of the dipole modulation parameter,…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relating the inhomogeneous power spectrum to the CMB hemispherical anisotropy

2015

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Probing Statistical Isotropy of Cosmological Radio Sources using Square Kilometre Array

et al. 2016

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There currently exist many observations which are not consistent with the cosmological principle. We review these observations with a particular emphasis on those relevant for Square Kilometre Array (SKA). In particular, several different data sets indicate a preferred direction pointing approximately towards the Virgo cluster. We also observe a hemispherical anisotropy in the Cosmic Microwave Background Radiation (CMBR) temperature fluctuations. Although these inconsistencies may be attributed to systematic effects, there remains the possibility that they indicate new physics and various theories have been proposed to explain them. One possibility, which we discuss in this review, is the generation of perturbation modes during the early pre-inflationary epoch, when the Universe may not obey the cosmological principle. Better measurements will provide better constraints on these theories. In particular, we propose measurement of the dipole in number counts, sky brightness, polarized flux and polarization orientations of radio sources. We also suggest test of alignment of linear polarizations of sources as a function of their relative separation. Finally we propose measurement of hemispherical anisotropy or equivalently dipole modulation in radio sources.

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Probing the statistical isotropy of the universe with Planck data of the cosmic microwave background

Kester,

Bernui,

Hipólito-Ricaldi

2024

A&A

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We study the angular distribution of temperature fluctuations in the cosmic microwave background (CMB) to probe the statistical isotropy of the universe by using precise full-sky CMB data with a model-independent approach. We investigated the temperature-temperature angular correlations in the four Planck foreground-cleaned CMB maps that were released recently. We performed a directional analysis on the CMB sphere to search directions in which the temperature-temperature angular correlations are extreme. Our analyses confirm a preferred axis in the CMB sphere, pointing in the direction $(l,b) circ circ )$, at the $98<!PCT!> -99<!PCT!>$ confidence level. In this direction, the CMB angular correlations exceed the antipodal direction most strongly. This preferred direction is unexpected in the Lambda CDM cosmological model and represents a significant deviation from results obtained by applying the same procedure to simulated statistically isotropic CMB maps. This result confirms the north-south asymmetry in the most recent Planck data. This phenomenon is one of the previously reported CMB anomalies. We performed a robust detection of the north-south asymmetry in the temperature-temperature angular correlations, with a slightly different statistical significance, in the four Planck foreground-cleaned CMB maps. Moreover, we performed consistency tests by adding foreground and noise, both Planck data products, to the CMB map we studied, and we also investigated and discarded possible bias in our method. After these detailed analyses, we conclude that the north-south asymmetry phenomenon is present with a high statistical significance in the Planck CMB maps we studied. This result confirms previous reports in the literature in the past 20 years.

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Testing the dipole modulation model in CMBR

Cited by 26 publications

References 28 publications

Relating the inhomogeneous power spectrum to the CMB hemispherical anisotropy

Relating the inhomogeneous power spectrum to the CMB hemispherical anisotropy

Probing Statistical Isotropy of Cosmological Radio Sources using Square Kilometre Array

Probing the statistical isotropy of the universe with Planck data of the cosmic microwave background

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