The gravitational and lensing-ISW bispectrum of 21 cm radiation

Schmit, Claude J; Heavens, Alan; Pritchard, Jonathan R.

doi:10.1093/mnras/sty3400

Cited by 10 publications

(9 citation statements)

References 97 publications

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“…We here observed the trend that excess skewness increases with redshift, which is also consistent with previous studies on gravitationally caused non-Gaussianity: Schmit et al (2019) show that the gravitational bispectrum is dominated by triangles of the squeezed and elongated type, consistent with our observed redshift trend, and Munshi et al (2020) show that the weak lensing bispectrum is also dominated by squeezed configurations. The amplitude of the weak lensing bispectrum equally grows with redshift, again consistent with the findings of this paper.…”

Section: Discussion Of Gravitational Skewnesssupporting

confidence: 92%

The impact of signal-to-noise, redshift, and angular range on the bias of weak lensing 2-point functions

Louca¹,

Sellentin²

2020

TheOJA

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Weak lensing data follow a naturally skewed distribution, implying the data vector most likely yielded from a survey will systematically fall below its mean. Although this effect is qualitatively known from CMB-analyses, correctly accounting for it in weak lensing is challenging, as a direct transfer of the CMB results is quantitatively incorrect. While a previous study (Sellentin et al. 2018) focused on the magnitude of this bias, we here focus on the frequency of this bias, its scaling with redshift, and its impact on the signal-to-noise of a survey. Filtering weak lensing data with COSEBIs, we show that weak lensing likelihoods are skewed up until ≈ 100, whereas CMB-likelihoods Gaussianize already at ≈ 20. While COSEBI-compressed data on KiDS-and DES-like redshift-and angular ranges follow Gaussian distributions, we detect skewness at 6σ significance for half of a Euclid-or LSST-like data set, caused by the wider coverage and deeper reach of these surveys. Computing the signal-to-noise ratio per data point, we show that precisely the data points of highest signal-to-noise are the most biased. Over all redshifts, this bias affects at least 10% of a survey's total signal-to-noise, at high redshifts up to 25%. The bias is accordingly expected to impact parameter inference. The bias can be handled by developing non-Gaussian likelihoods. Otherwise, it could be reduced by removing the data points of highest signal-to-noise.

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Section: Discussion Of Gravitational Skewnesssupporting

confidence: 92%

The impact of signal-to-noise, redshift, and angular range on the bias of weak lensing 2-point functions

Louca¹,

Sellentin²

2020

TheOJA

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“…In the weak lensing field progress have been made since the first seminal works (Takada & Jain 2004;Kilbinger & Schneider 2005), Rizzato et al (2018) investigated the information content of the bispectrum while Kayo et al (2013) forecasted parameters constraints using a covariance matrix with terms beyond the Gaussian approximation. 3pt statistic have also been applied to line intensity maps probes (Hoffmann et al 2019;Beane & Lidz 2018;Schmit et al 2019;Watkinson et al 2019).…”

Section: Introductionmentioning

confidence: 99%

GEOMAX: beyond linear compression for three-point galaxy clustering statistics

Gualdi

Gil-Marín

Manera

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Abstract We present the GEOMAX algorithm and its Python implementation for a two-step compression of bispectrum measurements. The first step groups bispectra by the geometric properties of their arguments; the second step then maximises the Fisher information with respect to a chosen set of model parameters in each group. The algorithm only requires the derivatives of the data vector with respect to the parameters and a small number of mock data, producing an effective, non-linear compression. By applying GEOMAX to bispectrum monopole measurements from BOSS DR12 CMASS redshift-space galaxy clustering data, we reduce the $68\%$ credible intervals for the inferred parameters (b1, b2, f, σ8) by $\left(50.4\%,56.1\%,33.2\%,38.3\%\right)$ with respect to standard MCMC on the full data vector. We run the analysis and comparison between compression methods over one hundred galaxy mocks to test the statistical significance of the improvements. On average GEOMAX performs $\sim 15\%$ better than geometrical or maximal linear compression alone and is consistent with being lossless. Given its flexibility, the GEOMAX approach has the potential to optimally exploit three-point statistics of various cosmological probes like weak lensing or line-intensity maps from current and future cosmological data-sets such as DESI, Euclid, PFS and SKA.

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“…Indeed, while in galaxy surveys broad z-bins can strongly reduce the impact of RSD on the observable power spectra or higher order statistics, broad z-bins in HI mapping remain foreground dominated. Previous works, for instance [49], have not included RSD in the bispectrum analysis. Moreover they based their results on the Limber approximation, which, as we have shown, fails completely for the slim z-bins required by HI mapping.…”

Section: The Hi Intensity Mapping Angular Bispectrummentioning

confidence: 99%

The full-sky angular bispectrum in redshift space

Dio

Durrer

Maartens

et al. 2019

J. Cosmol. Astropart. Phys.

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We compute the redshift-dependent angular bispectrum of galaxy number counts at tree-level, including nonlinear clustering bias and estimating numerically for the first time the effect of redshift space distortions (RSD). We show that for narrow redshift bins the amplitude of nonlinear RSD is comparable with the matter density perturbations. While our numerical results only include terms relevant on sub-horizon scales, the formalism can readily be extended to the full tree-level bispectrum. Our approach does not rely on the flat-sky approximation and it can be easily generalized to different sources by including the appropriate bias expansion. We test the accuracy of Limber approximation for different z-bins. We highlight the subtle but relevant differences in the angular bispectrum of galaxy number counts with respect to CMB, due to the different scale dependence of perturbations. Our formalism can also be directly applied to the angular HI intensity mapping bispectrum. 1

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The gravitational and lensing-ISW bispectrum of 21 cm radiation

Cited by 10 publications

References 97 publications

The impact of signal-to-noise, redshift, and angular range on the bias of weak lensing 2-point functions

The impact of signal-to-noise, redshift, and angular range on the bias of weak lensing 2-point functions

GEOMAX: beyond linear compression for three-point galaxy clustering statistics

The full-sky angular bispectrum in redshift space

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