Angular-planar CMB power spectrum

Pereira, T.; Abramo, L. Raul

doi:10.1103/physrevd.80.063525

Cited by 13 publications

(13 citation statements)

References 39 publications

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“…where the detailed form of the quantity on the right-hand side is model-dependent (see the more detailed discussions in [61][62][63]). There are many possibilities for how the absence of statistical isotropy might arise.…”

Section: E Cosmological Explanationsmentioning

confidence: 99%

Large‐Angle Anomalies in the CMB

Copi

Huterer

Schwarz

et al. 2010

Advances in Astronomy

227

242

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We review the recently found large-scale anomalies in the maps of temperature anisotropies in the cosmic microwave background. These include alignments of the largest modes of CMB anisotropy with each other and with geometry and direction of motion of the Solar System, and the unusually low power at these largest scales. We discuss these findings in relation to expectation from standard inflationary cosmology, their statistical significance, the tools to study them, and the various attempts to explain them.

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Section: E Cosmological Explanationsmentioning

confidence: 99%

Large‐Angle Anomalies in the CMB

Copi

Huterer

Schwarz

et al. 2010

Advances in Astronomy

227

242

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“…Several groups (de Oliveira-Costa et al 2004;Abramo et al 2006;Land & Magueijo 2007;Samal et al 2008;Rakić & Schwarz 2007) claim to have found a strong alignment between the preferred axes of the quadrupole and the octopole, which is commonly referred to as the axis of evil. Others (Bernui 2008;Eriksen et al 2007;Hoftuft et al 2009) have found a significant power asymmetry between the northern and southern ecliptic hemisphere, and some weaker anomalies have been found for the low multipoles beyond the octopole (Copi et al 2004;Land & Magueijo 2005;Abramo et al 2006;Pereira & Abramo 2009). However, the existence of such an isotropy breaking in the CMB temperature map is strongly under debate, and also negative results have been published (Souradeep et al 2006;Magueijo & Sorkin 2007).…”

Section: Introductionmentioning

confidence: 99%

The axis of evil - a polarization perspective

Frommert

Enßlin

2010

Monthly Notices of the Royal Astronomical Society

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We search for an unusual alignment of the preferred axes of the quadrupole and octopole, the so-called axis of evil, in the CMB temperature and polarization data from WMAP. We use the part of the polarization map which is uncorrelated with the temperature map as a statistically independent probe of the axis of evil, which helps to assess whether the latter has a cosmological origin or if is a mere chance fluctuation in the temperature. Note, though, that for certain models creating a preferred axis in the temperature map, we would not expect to see the axis in the uncorrelated polarization map. We find that the axis of the quadrupole of the uncorrelated polarization map roughly aligns with the axis of evil within our measurement precision, whereas the axis of the octopole does not. However, with our measurement uncertainty, the probability of such a scenario to happen by chance in an isotropic universe is of the order of 50 per cent. We also find that the so-called cold spot present in the CMB temperature map is even colder in the part of the temperature map which is uncorrelated with the polarization, although there is still a large uncertainty in the latter. Therefore, our analysis of the axis of evil and a future analysis of the cold spot in the uncorrelated temperature data will strongly benefit from the polarization data expected from the Planck satellite.Comment: Version accepted by MNRAS, added some comments, corrected typo

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“…Here we are primarily interested in answering: how to detect planar signatures in CMB maps? One possibility was recently proposed in [56], where the two-point correlation function is decomposed in such a way as to account for the presence of symmetry planes in temperature maps. Given that CMB experiments are confined to collecting data from inside our galactic plane, it is conceivable that we may find planar signatures in the data if foregrounds were improperly removed.…”

Section: Jcap12(2009)013mentioning

confidence: 99%

“…In this work we employ the angular-planar power spectrum analysis introduced in [56] to search for planar signatures both in partial and full sky-coverage temperature maps, allowing for possible effects due to residual foreground contaminations. Our analysis may therefore help to shed some light in the origin of the reported anomalies and test the robustness of cleaned maps due to foreground contamination in a model-independent way.…”

Section: Jcap12(2009)013mentioning

confidence: 99%

Searching for planar signatures in WMAP

Abramo¹,

Bernui²,

Pereira³

2009

J. Cosmol. Astropart. Phys.

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We search for planar deviations of statistical isotropy in the Wilkinson Microwave Anisotropy Probe (WMAP) data by applying a recently introduced angular-planar statistics both to full-sky and to masked temperature maps, including in our analysis the eect of the residual foreground contamination and systematics in the foreground removing process as sources of error. We conrm earlier ndings that full-sky maps exhibit anomalies at the planar (l) and angular ( ) scales (l, ) = (2, 5), (4, 7), and (6,8), which seem to be due to unremoved foregrounds since this features are present in the full-sky map but not in the masked maps. On the other hand, our test detects slightly anomalous results at the scales (l, ) = (10, 8) and (2,9) in the masked maps but not in the full-sky one, indicating that the foreground cleaning procedure (used to generate the full-sky map) could not only be creating false anomalies but also hiding existing ones. We also nd a signicant trace of an anomaly in the full-sky map at the scale (l, ) = (10, 5), which is still present when we consider galactic cuts of 18.3% and 28.4%. As regards the quadrupole ( = 2), we nd a coherent over-modulation over the whole celestial sphere, for all full-sky and cut-sky maps. Overall, our results seem to indicate that current CMB maps derived from WMAP data do not show signicant signs of anisotropies, as measured by our angular-planar estimator. However, we have detected a curious coherence of planar modulations at angular scales of the order of the galaxy's plane, which may be an indication of residual contaminations in the full-and cut-sky maps. PACS numbers: 98.80.-k, 98.70.Vc, 98.80.Es I. INTRODUCTIONThe statistical concordance model of the universe has now been established with unprecedent accuracy by the Wilkinson Microwave Anisotropy Probe (WMAP). The ve year dataset release of the WMAP team [1,2] has shown that to a very good extent the temperature eld of the cosmic microwave background radiation (CMB) obeys a Gaussian statistic with zero mean and a variance which is the same in every direction in the sky. At the same time, several dierent teams [3,4,5,6,7,8,9,10,11,12,13] have reported the detection of statistical peculiarities in this eld, mainly in the largest cosmological scales, which range from slightly to extremely unlikely within the framework of a Gaussian and statistically isotropic universe. Among these anomalies, the most conspicuous are the lack of power in the low-multipole sector and in the 2-point correlation function [3,6], the alignment of the quadrupole = 2 and the octopole = 3 [5,6,14], and the so-called north-south asymmetry [4,8,9,11,12,13,15,16,17,18,19]. Several attempts to explain away these statistical features in terms of known sources of microwave radiation or peculiarities of the instrument have been proposed, but have not yet produced a compelling explanation.If we put aside the hypotheses that these anomalies may possibly be due to some residual galactic contamination [20,21,22,23] or even to a systematic data analysis eect [...

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Angular-planar CMB power spectrum

Cited by 13 publications

References 39 publications

Large‐Angle Anomalies in the CMB

Large‐Angle Anomalies in the CMB

The axis of evil - a polarization perspective

Searching for planar signatures in WMAP

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