The performance of spherical wavelets to detect non-Gaussianity in the cosmic microwave background sky

Martínez-González, E.; Gallegos, J.; Argüeso, F.; Cayón, L.; Sanz, J. L.

doi:10.1046/j.1365-8711.2002.05648.x

Cited by 101 publications

(129 citation statements)

References 38 publications

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“…Therefore, wavelets could provide most of the signal-to-noise ratio of the ISW effect by just analysing a narrow range of scales. They were first proposed for the ISW detection by Vielva et al (2006), where the SMHW (Martínez-González et al 2002) was proposed as the filtering kernel. The basic idea of this approach is to estimate the covariance of the SMHW coefficients (SMHWcov) as a function of the wavelet scale (see e.g., Vielva et al 2006, for details).…”

Section: Wavelet Covariancementioning

confidence: 99%

Planck2013 results. XIX. The integrated Sachs-Wolfe effect

Ade¹,

Aghanim²,

Armitage-Caplan³

et al. 2014

A&A

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135

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Based on cosmic microwave background (CMB) maps from the 2013 Planck Mission data release, this paper presents the detection of the integrated Sachs-Wolfe (ISW) effect, that is, the correlation between the CMB and large-scale evolving gravitational potentials. The significance of detection ranges from 2 to 4σ, depending on which method is used. We investigated three separate approaches, which essentially cover all previous studies, and also break new ground. (i) We correlated the CMB with the Planck reconstructed gravitational lensing potential (for the first time). This detection was made using the lensing-induced bispectrum between the low-and high-temperature anisotropies; the correlation between lensing and the ISW effect has a significance close to 2.5σ. (ii) We cross-correlated with tracers of large-scale structure, which yielded a significance of about 3σ, based on a combination of radio (NVSS) and optical (SDSS) data. (iii) We used aperture photometry on stacked CMB fields at the locations of known large-scale structures, which yielded and confirms a 4σ signal, over a broader spectral range, when using a previously explored catalogue, but shows strong discrepancies in amplitude and scale when compared with expectations. More recent catalogues give more moderate results that range from negligible to 2.5σ at most, but have a more consistent scale and amplitude, the latter being still slightly higher than what is expected from numerical simulations within ΛCMD. Where they can be compared, these measurements are compatible with previous work using data from WMAP, where these scales have been mapped to the limits of cosmic variance. Planck's broader frequency coverage allows for better foreground cleaning and confirms that the signal is achromatic, which makes it preferable for ISW detection. As a final step we used tracers of large-scale structure to filter the CMB data, from which we present maps of the ISW temperature perturbation. These results provide complementary and independent evidence for the existence of a dark energy component that governs the currently accelerated expansion of the Universe.

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Section: Wavelet Covariancementioning

confidence: 99%

Planck2013 results. XIX. The integrated Sachs-Wolfe effect

Ade¹,

Aghanim²,

Armitage-Caplan³

et al. 2014

A&A

Self Cite

135

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“…The CS was found by applying the Spherical Mexican Hat Wavelet (SMHW, Martínez-González et al 2002) to the WMAP data (Bennett et al 2003). Convolving a CMB map with the SMHW at a particular wavelet scale increases the signal to noise ratio at that scale.…”

Section: Detection and Significancementioning

confidence: 99%

The WMAP Cold Spot

Cruz¹,

Martínez-González²,

Vielva³

2010

Astrophysics and Space Science Proceedings

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The WMAP cold spot was found by applying spherical wavelets to the first year WMAP data. An excess of kurtosis of the wavelet coefficient was observed at angular scales of around 5 degrees. This excess was shown to be inconsistent with Gaussian simulations with a p-value of around 1%. A cold spot centered at (b = −57 • , l = 209 • ) was shown to be the main cause of this deviation. Several hypotheses were raised to explain the origin of the cold spot. After performing a Bayesian template fit a collapsing cosmic texture was found to be the most probable hypothesis explaining the spot. Here we review the properties of the cold spot and the possible explanations.

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“…It has been adopted in CMB-related analyses of non-Gaussianity (Hobson et al 1999;Barreiro et al 2000;Aghanim et al 2003;Cayón et al 2001Cayón et al , 2003Martínez-González et al 2002;Mukherjee & Wang 2004;Vielva et al 2004;McEwen et al 2005;Liu & Zhang 2005). In wavelet space, the cross-correlation covariance at a given scale a is defined as (Vielva et al 2006), where q CMB (a, p) and q EGRET (a, p) are the wavelet coefficients of the WMAP and EGRET data at a position p on the sky map and the sum is extended over all p the pixels (N a ) that are not removed by the Galactic mask "Kp0" (Bennett et al 2003b).…”

Section: Cross-correlation In Wavelet Spacementioning

confidence: 99%

“…The corresponding fast algorithms and the exact expression of the wavelet coefficients can be found in Wiaux et al (2005bWiaux et al ( , 2005c. Martínez-González et al (2002) have described the projection for the spherical Mexican hat wavelet (SMHW), as well as its properties, whereas the spherical Morlet wavelet (SMW) has been applied to non-Gaussianity detection in the WMAP data (McEwen et al 2005;Liu & Zhang 2005). In this correlation study we have adopted both wavelets, of which SMW seems to be more sensitive than SMHW.…”

Section: Cross-correlation In Wavelet Spacementioning

confidence: 99%

A Cross-Correlation Analysis of WMAP and EGRET Data in Wavelet Space

Liu

Zhang

2005

ApJ

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We cross-correlate the first-year Wilkinson Microwave Anisotropy Probe (WMAP) data and the diffuse gammaray intensity maps from the Energetic Gamma-Ray Experiment Telescope (EGRET) using spherical-wavelet approaches. Correlations at the 99.7% significance level have been detected, at scales around 15Њ in the WMAP foreground-cleaned W-band and Q-band maps, based on data from regions that are outside the most conservative WMAP foreground mask; no significant correlation is found with the Tegmark cleaned map. The detected correlation is most likely of Galactic origin and thus can help probe the origins of possible Galactic foreground residuals and ultimately remove them from measured microwave sky maps.

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The performance of spherical wavelets to detect non-Gaussianity in the cosmic microwave background sky

Cited by 101 publications

References 38 publications

Planck2013 results. XIX. The integrated Sachs-Wolfe effect

Planck2013 results. XIX. The integrated Sachs-Wolfe effect

The WMAP Cold Spot

A Cross-Correlation Analysis of WMAP and EGRET Data in Wavelet Space

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