The Non‐Gaussian Cold Spot in the 3 Year<i>Wilkinson Microwave Anisotropy Probe</i>Data

Cruz, M.; Cayón, L.; Martínez-González, E.; Vielva, P.; Jin, Jiashun

doi:10.1086/509703

Cited by 208 publications

(211 citation statements)

References 45 publications

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“…Inoue & Silk (2007) explained observed large-angle CMB anomalies with a pair of local dust-filled voids. These would cause both a cold spot in CMB data and fluctuations in Mariano & Perivolaropoulos (2012) and Schwarz & Weinhorst (2007) (data set A , B ♣, D ♠), and with the direction of the CMB dipole moment ♥ (Lineweaver et al 1996), the Shapley supercluster (Raychaudhury 1989), the cold spots I (Bennett et al 2011) and II detected in WMAP data (Cruz et al 2007), and the South Equatorial Pole S . the locally measured Hubble constant as large as 2-4%.…”

Section: Resultsmentioning

confidence: 99%

Constraints on anisotropic cosmic expansion from supernovae

Kalus

Schwarz

Seikel

et al. 2013

A&A

105

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Aims. We test the isotropy of the expansion of the Universe by estimating the hemispherical anisotropy of supernova type Ia (SN Ia) Hubble diagrams at low redshifts (z < 0.2). Methods. We compare the best fit Hubble diagrams in pairs of hemispheres and search for the maximal asymmetric orientation. For an isotropic Universe, we expect only a small asymmetry due to noise and the presence of nearby structures. This test does not depend on the assumed content of the Universe, the assumed model of gravity, or the spatial curvature of the Universe. The expectation for possible fluctuations due to large scale structure is evaluated for the Λ cold dark matter (ΛCDM) model and is compared to the supernova data from the Constitution set for four different light curve fitters, thus allowing a study of the systematic effects. Results. The expected order of magnitude of the hemispherical asymmetry of the Hubble expansion agrees with the observed one. The direction of the Hubble asymmetry is established at 95% confidence level (C.L.) using both, the MLCS2k2 and the SALT II light curve fitter. The highest expansion rate is found towards ( , b) ≈ (−35 • , −19 • ), which agrees with directions reported by other studies. Its amplitude is not in contradiction to expectations from the ΛCDM model. The measured Hubble anisotropy is ΔH/H ∼ 0.026. With 95% C.L. the expansion asymmetry is ΔH/H < 0.038.

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Section: Resultsmentioning

confidence: 99%

Constraints on anisotropic cosmic expansion from supernovae

Kalus

Schwarz

Seikel

et al. 2013

A&A

105

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“…The cosmic microwave background data released by the Planck Satellite [480,16] confirms the existence of several large-scale statistical "anomalies" in the temperature maps, most of which were also observed in the WMAP data. Amongst these, the most robust seem to be: the quadrupole-octupole alignment [491,492,483,484,485,487,489]; the hemispherical asymmetry in power between the "northern" and "southern" hemispheres [476,477,493,478,479,480,481,16]; the existence of a Cold Spot [494,495,496,16]; the lack of angular correlation between separations of 60 degrees and larger [486,487,488,480]; and the point-parity asymmetry [497,498,499,500,501,16]. If not due to statistical flukes [502], these anomalies represent both the possibility of new physics at high energy scales and/or a hint of unknown systematics in the map-cleaning procedure (see e.g.…”

Section: Anomaly Detection: a How-to Guidementioning

confidence: 99%

BeyondΛCDM: Problems, solutions, and the road ahead

Bull

Akrami

Adamek

et al. 2016

Physics of the Dark Universe

420

210

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Despite its continued observational successes, there is a persistent (and growing) interest in extending cosmology beyond the standard model, ΛCDM. This is motivated by a range of apparently serious theoretical issues, involving such questions as the cosmological constant problem, the particle nature of dark matter, the validity of general relativity on large scales, the existence of anomalies in the CMB and on small scales, and the predictivity and testability of the inflationary paradigm. In this paper, we summarize the current status of ΛCDM as a physical theory, and review investigations into possible alternatives along a number of different lines, with a particular focus on highlighting the most promising directions. While the fundamental problems are proving reluctant to yield, the study of alternative cosmologies has led to considerable progress, with much more to come if hopes about forthcoming high-precision observations and new theoretical ideas are fulfilled.Keywords: cosmology -dark energy -cosmological constant problem -modified gravitydark matter -early universe Cosmology has been both blessed and cursed by the establishment of a standard model: ΛCDM. On the one hand, the model has turned out to be extremely predictive, explanatory, and observationally robust, providing us with a substantial understanding of the formation of large-scale structure, the state of the early Universe, and the cosmic abundance of different types of matter and energy. It has also survived an impressive battery of precision observational tests -anomalies are few and far between, and their significance is contentious where they do arise -and its predictions are continually being vindicated through the discovery of new effects (B-mode polarization [1] and lensing [2,3] of the cosmic microwave background (CMB), and the kinetic Sunyaev-Zel'dovich effect [4] being some recent examples). These are the hallmarks of a good and valuable physical theory.On the other hand, the model suffers from profound theoretical difficulties. The two largest contributions to the energy content at late times -cold dark matter (CDM) and the cosmological constant (Λ) -have entirely mysterious physical origins. CDM has so far evaded direct detection by laboratory experiments, and so the particle field responsible for it -presumably a manifestation of "beyond the standard model" particle physics -is unknown. Curious discrepancies also appear to exist between the predicted clustering properties of CDM on small scales and observations. The cosmological constant is even more puzzling, giving rise to quite simply the biggest problem in all of fundamental physics: the question of why Λ appears to take such an unnatural value [5,6,7]. Inflation, the theory of the very early Universe, has also been criticized for being fine-tuned and under-predictive [8], and appears to leave many problems either unsolved or fundamentally unresolvable. These problems are indicative of a crisis.From January 14th-17th 2015, we held a conference in Oslo, Norway to surve...

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“…Because the asymmetry was coincidentally found in the same quadrant as the so-called cold spot (see Cruz et al 2007;Vielva & Sanz 2010), we tested if they are possibly correlated. We masked the cold spot region which is centered on φ = 209 • and θ = 141 • , and calculated the TPCF for the SEQ using also the KQ85 mask.…”

Section: The Cold Spotmentioning

confidence: 99%

“…Other anomalies were found in the WMAP data that were not expected according to the ΛCDM model either, such as the alignment between the quadrupole and octopole (e.g. Bielewicz et al 2004;Schwarz et al 2004;Copi et al 2004;de Oliveira-Costa et al 2004;Bielewicz et al 2005;Land & Magueijo 2005;Copi et al 2006;Abramo et al 2006;Frommert & Ensslin 2010;Gruppuso & Burigana 2010), the low quadrupole and octopole amplitudes (e.g., Mukherjee & Wang 2003;Ayata et al 2010;Cayon 2010;Cruz et al 2011), the north-south asymmetry (e.g., Eriksen et al 2004a;Hansen et al 2004a;Eriksen et al 2004b;Hansen et al 2004b;Donoghue et al 2005;Hoftuft et al 2009;Paci et al 2010;Pietrobon et al 2010;Vielva & Sanz 2010), the anomalous alignment of the CMB features toward the Ecliptic poles (e.g., Wiaux et al 2006;Vielva et al 2007), and the cold spot (e.g., Vielva et al 2004;Cruz et al 2005Cruz et al , 2007Vielva 2010).…”

Section: Introductionmentioning

confidence: 99%

Asymmetries in the angular distribution of the cosmic microwave background

Santos

Villela

Wuensche

2012

A&A

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Context. Intriguing features in the angular distribution of the cosmic microwave background (CMB), such as the north-south asymmetry, were reported in the one-and three-year Wilkinson Microwave Anisotropy Probe (WMAP) data and should be studied in detail. We investigate some of these asymmetries in the CMB temperature angular distribution considering the ΛCDM model in the three, five, and seven year WMAP data.Aims. We aim to analyze the four quadrants of the internal linear combination (ILC) CMB maps using three different Galactic cuts: the WMAP KQ85 mask, a |b| < 10 • Galactic cut, and the WMAP KQ85 mask + |b| < 10 • Galactic cut. Methods. We used the two-point angular correlation function (TPCF) in the WMAP maps for each of their quadrants. The same procedure was performed for 1000 Monte Carlo (MC) simulations that were produced using the WMAP team ΛCDM best-fit power spectrum. In addition, we changed the quadrupole and octopole amplitudes obtained from the ΛCDM model spectrum. We changed this to fit the quadrupole and octopole amplitudes to their observable values from the WMAP data. We repeated the analysis for the 1000 simulations of this modified ΛCDM model, hereafter MΛCDM. Results. Our analysis showed asymmetries between the southeastern quadrant (SEQ) and the other quadrants (southwestern quadrant (SWQ), northeastern quadrant (NEQ) and northwestern quadrant (NWQ)). Over all WMAP ILC maps, the probability for the occurrence of the SEQ-NEQ, SEQ-SWQ and SEQ-NWQ asymmetries varies from 0.1% (SEQ-NEQ) to 8.5% (SEQ-SWQ) using the KQ85 mask and the KQ85 mask + |b| < 10 • Galactic cut, respectively. We also calculated the probabilities for the MΛCDM using only the KQ85 mask and found no significant differences in the results. Moreover, the cold spot region located in the SEQ quadrant was covered with masks of 5, 10 and 15 degrees radius and again the results remained unchanged. Furthermore, this analysis was repeated for random regions in the SEQ quadrant with a 15-degree mask and the SEQ quadrant still remained asymmetric with respect to the other quadrants of the CMB map. Conclusions. We found an excess of power in the TPCF at scales >100 degrees in the SEQ with respect to the other quadrants that is independent of the Galactic cut used. Moreover, we tested a possible relation between the cold spot and the SEQ excess of power and found no evidence for it. Finally, we could not find any specific region within the SEQ that might be considered responsible for the quadrant asymmetry.

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The Non‐Gaussian Cold Spot in the 3 YearWilkinson Microwave Anisotropy ProbeData

Cited by 208 publications

References 45 publications

Constraints on anisotropic cosmic expansion from supernovae

Constraints on anisotropic cosmic expansion from supernovae

BeyondΛCDM: Problems, solutions, and the road ahead

Asymmetries in the angular distribution of the cosmic microwave background

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