scholarly journals Perturbation theory challenge for cosmological parameters estimation: Matter power spectrum in real space

2019 ◽  
Vol 99 (6) ◽  
Author(s):  
Ken Osato ◽  
Takahiro Nishimichi ◽  
Francis Bernardeau ◽  
Atsushi Taruya
Keyword(s):  
Perturbation Theory ◽  
Power Spectrum ◽  
Cosmological Parameters ◽  
Real Space ◽  
Parameters Estimation ◽  
Matter Power Spectrum

scholarly journals Primordial power spectrum and cosmology from black-box galaxy surveys

2019 ◽  
Vol 490 (3) ◽  
pp. 4237-4253 ◽  
Author(s):  
Florent Leclercq ◽  
Wolfgang Enzi ◽  
Jens Jasche ◽  
Alan Heavens
Keyword(s):  
Power Spectrum ◽  
Numerical Models ◽  
A Priori ◽  
Cosmological Parameters ◽  
Physical Structure ◽  
Black Box ◽  
Acoustic Oscillations ◽  
Galaxy Surveys ◽  
Matter Power Spectrum ◽  
Primordial Power Spectrum

ABSTRACT We propose a new, likelihood-free approach to inferring the primordial matter power spectrum and cosmological parameters from arbitrarily complex forward models of galaxy surveys where all relevant statistics can be determined from numerical simulations, i.e. black boxes. Our approach, which we call simulator expansion for likelihood-free inference (selfi), builds upon approximate Bayesian computation using a novel effective likelihood, and upon the linearization of black-box models around an expansion point. Consequently, we obtain simple ‘filter equations’ for an effective posterior of the primordial power spectrum, and a straightforward scheme for cosmological parameter inference. We demonstrate that the workload is computationally tractable, fixed a priori, and perfectly parallel. As a proof of concept, we apply our framework to a realistic synthetic galaxy survey, with a data model accounting for physical structure formation and incomplete and noisy galaxy observations. In doing so, we show that the use of non-linear numerical models allows the galaxy power spectrum to be safely fitted up to at least kmax = 0.5 h Mpc−1, outperforming state-of-the-art backward-modelling techniques by a factor of ∼5 in the number of modes used. The result is an unbiased inference of the primordial matter power spectrum across the entire range of scales considered, including a high-fidelity reconstruction of baryon acoustic oscillations. It translates into an unbiased and robust inference of cosmological parameters. Our results pave the path towards easy applications of likelihood-free simulation-based inference in cosmology. We have made our code pyselfi and our data products publicly available at http://pyselfi.florent-leclercq.eu.

scholarly journals Modelling the post-reionization neutral hydrogen (H i) 21-cm bispectrum

2019 ◽  
Vol 490 (2) ◽  
pp. 2880-2889 ◽  
Author(s):  
Debanjan Sarkar ◽  
Suman Majumdar ◽  
Somnath Bharadwaj
Keyword(s):  
Perturbation Theory ◽  
Power Spectrum ◽  
Cosmological Parameters ◽  
Neutral Hydrogen ◽  
Order Perturbation ◽  
Order Perturbation Theory ◽  
Intensity Mapping ◽  
High Level ◽  
Second Order Perturbation Theory ◽  
Good Agreement

ABSTRACT Measurements of the post-reionization 21-cm bispectrum $B_{{\rm H\,{\small I}}\, }(\boldsymbol {k_1},\boldsymbol {k_2},\boldsymbol {k_3})$ using various upcoming intensity mapping experiments hold the potential for determining the cosmological parameters at a high level of precision. In this paper, we have estimated the 21-cm bispectrum in the z range 1 ≤ z ≤ 6 using seminumerical simulations of the neutral hydrogen (H i) distribution. We determine the k and z range where the 21-cm bispectrum can be adequately modelled using the predictions of second-order perturbation theory, and we use this to predict the redshift evolution of the linear and quadratic H i bias parameters b1 and b2, respectively. The b1 values are found to decrease nearly linearly with decreasing z, and are in good agreement with earlier predictions obtained by modelling the 21-cm power spectrum $P_{{\rm H\,{\small I}}\, }(k)$. The b2 values fall sharply with decreasing z, becomes zero at z ∼ 3 and attains a nearly constant value b2 ≈ −0.36 at z < 2. We provide polynomial fitting formulas for b1 and b2 as functions of z. The modelling presented here is expected to be useful in future efforts to determine cosmological parameters and constrain primordial non-Gaussianity using the 21-cm bispectrum.

scholarly journals Matter power spectrum from a Lagrangian-space regularization of perturbation theory

2013 ◽  
Vol 87 (8) ◽  
Author(s):  
Patrick Valageas ◽  
Takahiro Nishimichi ◽  
Atsushi Taruya
Keyword(s):  
Perturbation Theory ◽  
Power Spectrum ◽  
Matter Power Spectrum

scholarly journals Mixed dark matter: matter power spectrum and halo mass function

2021 ◽  
Vol 2021 (12) ◽  
pp. 044
Author(s):  
G. Parimbelli ◽  
G. Scelfo ◽  
S.K. Giri ◽  
A. Schneider ◽  
M. Archidiacono ◽  
...  
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Mass Function ◽  
Large Set ◽  
Cluster Number ◽  
Matter Power Spectrum ◽  
Wide Range ◽  
The Impact

Abstract We investigate and quantify the impact of mixed (cold and warm) dark matter models on large-scale structure observables. In this scenario, dark matter comes in two phases, a cold one (CDM) and a warm one (WDM): the presence of the latter causes a suppression in the matter power spectrum which is allowed by current constraints and may be detected in present-day and upcoming surveys. We run a large set of N-body simulations in order to build an efficient and accurate emulator to predict the aforementioned suppression with percent precision over a wide range of values for the WDM mass, Mwdm, and its fraction with respect to the totality of dark matter, fwdm. The suppression in the matter power spectrum is found to be independent of changes in the cosmological parameters at the 2% level for k≲ 10 h/Mpc and z≤ 3.5. In the same ranges, by applying a baryonification procedure on both ΛCDM and CWDM simulations to account for the effect of feedback, we find a similar level of agreement between the two scenarios. We examine the impact that such suppression has on weak lensing and angular galaxy clustering power spectra. Finally, we discuss the impact of mixed dark matter on the shape of the halo mass function and which analytical prescription yields the best agreement with simulations. We provide the reader with an application to galaxy cluster number counts.

scholarly journals Contributions from primordial non-Gaussianity and general relativity to the galaxy power spectrum

2021 ◽  
Vol 2021 (12) ◽  
pp. 025
Author(s):  
Rebeca Martinez-Carrillo ◽  
Juan Carlos Hidalgo ◽  
Karim A. Malik ◽  
Alkistis Pourtsidou
Keyword(s):  
General Relativity ◽  
Power Spectrum ◽  
Stage Iv ◽  
Real Space ◽  
Order Effects ◽  
Leading Order ◽  
Bias Parameter ◽  
Matter Power Spectrum ◽  
The Galaxy ◽  
The One

Abstract We compute the real space galaxy power spectrum, including the leading order effects of General Relativity and primordial non-Gaussianity from the f NL and g NL parameters. Such contributions come from the one-loop matter power spectrum terms dominant at large scales, and from the factors of the non-linear bias parameter b NL (akin to the Newtonian b ϕ). We assess the detectability of these contributions in Stage-IV surveys. In particular, we note that specific values of the bias parameter may erase the primordial and relativistic contributions to the configuration space power spectrum.

scholarly journals Power spectrum of halo intrinsic alignments in simulations

2020 ◽  
Vol 501 (1) ◽  
pp. 833-852
Author(s):  
Toshiki Kurita ◽  
Masahiro Takada ◽  
Takahiro Nishimichi ◽  
Ryuichi Takahashi ◽  
Ken Osato ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Cosmological Parameters ◽  
Three Dimensional ◽  
Power Spectra ◽  
Acoustic Oscillations ◽  
Matter Power Spectrum ◽  
Sample Covariance ◽  
Non Linear

ABSTRACT We use a suite of N-body simulations to study intrinsic alignments (IA) of halo shapes with the surrounding large-scale structure in the ΛCDM model. For this purpose, we develop a novel method to measure multipole moments of the three-dimensional power spectrum of the E-mode field of halo shapes with the matter/halo distribution, $P_{\delta E}^{(\ell)}(k)$ (or $P^{(\ell)}_{{\rm h}E}$), and those of the auto-power spectrum of the E-mode, $P^{(\ell)}_{EE}(k)$, based on the E/B-mode decomposition. The IA power spectra have non-vanishing amplitudes over the linear to non-linear scales, and the large-scale amplitudes at k ≲ 0.1 h−1 Mpc are related to the matter power spectrum via a constant coefficient (AIA), similar to the linear bias parameter of galaxy or halo density field. We find that the cross- and auto-power spectra PδE and PEE at non-linear scales, k ≳ 0.1 h−1 Mpc, show different k-dependences relative to the matter power spectrum, suggesting a violation of the non-linear alignment model commonly used to model contaminations of cosmic shear signals. The IA power spectra exhibit baryon acoustic oscillations, and vary with halo samples of different masses, redshifts, and cosmological parameters (Ωm, S8). The cumulative signal-to-noise ratio for the IA power spectra is about 60 per cent of that for the halo density power spectrum, where the super-sample covariance is found to give a significant contribution to the total covariance. Thus our results demonstrate that the IA power spectra of galaxy shapes, measured from imaging and spectroscopic surveys for an overlapping area of the sky, can be used to probe the underlying matter power spectrum, the primordial curvature perturbations, and cosmological parameters, in addition to the standard galaxy density power spectrum.

scholarly journals Impact of cosmological signatures in two-point statistics beyond the linear regime

2020 ◽  
Author(s):  
D V Gomez-Navarro ◽  
A J Mead ◽  
A Aviles ◽  
A de la Macorra
Keyword(s):  
Perturbation Theory ◽  
Correlation Function ◽  
Power Spectrum ◽  
Large Scale ◽  
Line Of Sight ◽  
Linear Regime ◽  
Dark Sector ◽  
Linear Evolution ◽  
Matter Power Spectrum ◽  
Small Scales

Abstract Some beyond ΛCDM cosmological models have dark-sector energy densities that suffer phase transitions. Fluctuations entering the horizon during such a transition can receive enhancements that ultimately show up as a distinctive bump in the power spectrum relative to a model with no phase transition. In this work, we study the non-linear evolution of such signatures in the matter power spectrum and correlation function using N-body simulations, perturbation theory and hmcode- a halo-model based method. We focus on modelling the response, computed as the ratio of statistics between a model containing a bump and one without it, rather than in the statistics themselves. Instead of working with a specific theoretical model, we inject a parametric family of Gaussian bumps into otherwise standard ΛCDM spectra. We find that even when the primordial bump is located at linear scales, non-linearities tend to produce a second bump at smaller scales. This effect is understood within the halo model due to a more efficient halo formation. In redshift space these nonlinear signatures are partially erased because of the damping along the line-of-sight direction produced by non-coherent motions of particles at small scales. In configuration space, the bump modulates the correlation function reflecting as oscillations in the response, as it is clear in linear Eulerian theory; however, they become damped because large scale coherent flows have some tendency to occupy regions more depleted of particles. This mechanism is explained within Lagrangian Perturbation Theory and well captured by our simulations.

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