Impact of large-scale tides on cosmological distortions via redshift-space power spectrum

Akitsu, Kazuyuki; Takada, Masahiro

doi:10.1103/physrevd.97.063527

Cited by 39 publications

(56 citation statements)

References 66 publications

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“…In Section II A we review the galaxy power spectrum including the super-sample effect at leading order. [23]. In Section II B, we explain the (BipoSH) decomposition formalism of the three-dimensional power spectrum.…”

Section: Preliminariesmentioning

confidence: 99%

“…where ∂P g (k, µ)/∂δ b and ∂P g (k,n)/∂τ ij are the responses of the galaxy power spectrum to the δ b and τ ij respectively, which represent the scale-dependent modulation to the observed power spectrum caused by the super-sample modes and µ is the cosine between the wave vector k and the line-of-sight (LOS)n. Notice that the response to the isotropic super-sample mode δ b can depend on only k and µ because it preserves the rotational symmetry around the observer. This mode-coupling between long-and short-wavelength modes is then characterized by the squeezed limit of the bispectrum [23,24,28]. In particular, the responses are related to the squeezed bispectrum [23] lim q→0…”

Section: Power Spectrum Responses To the Super-sample Modesmentioning

confidence: 99%

“…This mode-coupling between long-and short-wavelength modes is then characterized by the squeezed limit of the bispectrum [23,24,28]. In particular, the responses are related to the squeezed bispectrum [23] lim q→0…”

Section: Power Spectrum Responses To the Super-sample Modesmentioning

confidence: 99%

“…(7), one can obtain the explicit form of the response functions from the squeezed bispectrum. Using the standard perturbation theory [9], the tree-level squeezed bispectrum in redshift space is expressed as [23,28]…”

Section: Power Spectrum Responses To the Super-sample Modesmentioning

confidence: 99%

“…is known as the Alcock-Paczyński (AP) effect [22]. Besides these well-known effects, the super-sample tidal modes also generate a new anisotropic signature in the redshift-space galaxy power spectrum [18,[23][24][25]. These similar effects tend to give rise to degeneracies in cosmological parameter estimation [23,25].…”

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Super-sample tidal modes on the celestial sphere

2019

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The super-sample tidal effect carries information on long-wavelength fluctuations that we cannot measure directly. It arises from the mode-coupling between short-wavelength and long-wavelength perturbations beyond a finite region of a galaxy survey and violates statistical isotropy of observed galaxy power spectra. In this paper, we propose the use of bipolar spherical harmonic (BipoSH) decomposition formalism to characterize statistically anisotropic power spectra. Using the BipoSH formalism, we perform a comprehensive study of the effect of the super-sample tides on measurements of other cosmological distortions such as the redshift-space distortion (RSD) and Alcock-Paczyński (AP) effects by means of the Fisher information matrix formalism. We find that the BipoSH formalism can break parameter degeneracies among the super-sample tidal, RSD and AP effects, indicating that the super-sample tides have little impact on the measurements of the RSD and AP effects. We also show that the super-sample tides are detectable with an accuracy better than the ΛCDM prediction without impairing the accuracy of measurements of other anisotropies assuming a SPHEREx-like galaxy survey.

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Section: Preliminariesmentioning

confidence: 99%

Section: Power Spectrum Responses To the Super-sample Modesmentioning

confidence: 99%

Section: Power Spectrum Responses To the Super-sample Modesmentioning

confidence: 99%

Section: Power Spectrum Responses To the Super-sample Modesmentioning

confidence: 99%

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Super-sample tidal modes on the celestial sphere

2019

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The impact of braiding covariance and in-survey covariance on next-generation galaxy surveys

Lacasa

2020

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As galaxy surveys become more precise with lower noise and pushing to small non-linear scales, the need for accurate covariances beyond the vanilla Gaussian formula becomes more acute. Here, I investigate the analytical implementation and impact of non-Gaussian covariance terms that I uncovered for the galaxy angular power spectrum (Lacasa 2018). Braiding covariance is such an interesting class of these new terms, that gets contribution both from in-survey and super-survey modes, the latter being hard to calibrate with simulations. I present an approximation to Braiding covariance making it fast to compute numerically. I show that accounting for Braiding covariance is necessary to include other non-Gaussian terms, namely the in-survey 2-, 3-and 4-halo covariance. Indeed the latter quantify coupling between large and small scales, and would yield incorrect covariance matrices with negative eigenvalues, if left alone. I then move to quantify the impact on parameter constraints, with forecasts for a survey with Euclid-like galaxy density and angular scales. Compared with the Gaussian case, Braiding and in-survey covariances significantly increase the error bars on all cosmological parameters of the wCDM model, in particular by 50% for the Dark Energy equation of state w. The error bars on Halo Occupation Distribution (HOD) parameters are also affected between 12% and 39% . Accounting for super-sample covariance (SSC) also increases parameter errors, by 90% for w and between 7% and 64% for HOD. In total, non-Gaussianity increases the error bar on w by 120% (between 15% and 80% for other cosmological parameters), and the error bars on HOD parameters between 17% and 85%. Accounting for the 1-halo trispectrum term on top of SSC, as one in some current analyses, is not sufficient to capture the full non-Gaussian impact: Braiding and the rest of in-survey covariance have to be accounted for. I finally discuss why the inclusion of non-Gaussianity generally eases up parameter degeneracies, making cosmological constraints more robust to astrophysical uncertainties. Data and a notebook reproducing all plots and results are available at https://github. com/fabienlacasa/BraidingArticle Key words. methods: analytical -large-scale structure of the universe Article number, page 1 of 10

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An empirical nonlinear power spectrum overdensity response

Rácz

Szapudi

Csabai

2022

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Context. The overdensity inside a cosmological sub-volume and the tidal fields from its surroundings affect the matter distribution of the region. The resulting difference between the local and global power spectra is characterized by the response function. Aims. Our aim is to provide a new, simple, and accurate formula for the power spectrum overdensity response at highly nonlinear scales based on the results of cosmological simulations and paying special attention to the lognormal nature of the density field. Methods. We measured the dark matter power spectrum amplitude as a function of the overdensity (δW) in N-body simulation subsamples. We show that the response follows a power-law form in terms of (1 + δW), and we provide a new fit in terms of the variance, σ(L), of a sub-volume of size L. Results. Our fit has a similar accuracy and a comparable complexity to second-order standard perturbation theory on large scales, but it is also valid for nonlinear (smaller) scales, where perturbation theory needs higher-order terms for a comparable precision. Furthermore, we show that the lognormal nature of the overdensity distribution causes a previously unidentified bias: the power spectrum amplitude for a subsample with an average density is typically underestimated by about −2σ2. Although this bias falls to the sub-percent level above characteristic scales of 200 Mpc h−1, taking it into account improves the accuracy of estimating power spectra from zoom-in simulations and smaller high-resolution surveys embedded in larger low-resolution volumes.

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Impact of large-scale tides on cosmological distortions via redshift-space power spectrum

Cited by 39 publications

References 66 publications

Super-sample tidal modes on the celestial sphere

Super-sample tidal modes on the celestial sphere

The impact of braiding covariance and in-survey covariance on next-generation galaxy surveys

An empirical nonlinear power spectrum overdensity response

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