scholarly journals On the road to per cent accuracy – II. Calibration of the non-linear matter power spectrum for arbitrary cosmologies

2019 ◽  
Vol 490 (4) ◽  
pp. 4826-4840 ◽  
Author(s):  
Benjamin Giblin ◽  
Matteo Cataneo ◽  
Ben Moews ◽  
Catherine Heymans
Keyword(s):  
Power Spectrum ◽  
Initial Conditions ◽  
Power Spectra ◽  
Linear Regime ◽  
The Road ◽  
Matter Power Spectrum ◽  
Non Linear ◽  
Standard Cosmological Model ◽  
Massive Neutrinos ◽  
On The Road

ABSTRACT We introduce an emulator approach to predict the non-linear matter power spectrum for broad classes of beyond-ΛCDM cosmologies, using only a suite of ΛCDM N-body simulations. By including a range of suitably modified initial conditions in the simulations, and rescaling the resulting emulator predictions with analytical ‘halo model reactions’, accurate non-linear matter power spectra for general extensions to the standard ΛCDM model can be calculated. We optimize the emulator design by substituting the simulation suite with non-linear predictions from the standard halofit tool. We review the performance of the emulator for artificially generated departures from the standard cosmology as well as for theoretically motivated models, such as f(R) gravity and massive neutrinos. For the majority of cosmologies we have tested, the emulator can reproduce the matter power spectrum with errors ${\lesssim}1{{\ \rm per\ cent}}$ deep into the highly non-linear regime. This work demonstrates that with a well-designed suite of ΛCDM simulations, extensions to the standard cosmological model can be tested in the non-linear regime without any reliance on expensive beyond-ΛCDM simulations.

scholarly journals On the road to per cent accuracy – III. Non-linear reaction of the matter power spectrum to massive neutrinos

2019 ◽  
Vol 491 (3) ◽  
pp. 3101-3107 ◽  
Author(s):  
M Cataneo ◽  
J D Emberson ◽  
D Inman ◽  
J Harnois-Déraps ◽  
C Heymans
Keyword(s):  
Power Spectrum ◽  
Cold Dark Matter ◽  
New Physics ◽  
Model Reaction ◽  
Matter Power Spectrum ◽  
Non Linear ◽  
Cent Level ◽  
Massive Neutrinos ◽  
On The Road ◽  
Total Matter

ABSTRACT We analytically model the non-linear effects induced by massive neutrinos on the total matter power spectrum using the halo model reaction framework of Cataneo et al. In this approach, the halo model is used to determine the relative change to the matter power spectrum caused by new physics beyond the concordance cosmology. Using standard fitting functions for the halo abundance and the halo mass–concentration relation, the total matter power spectrum in the presence of massive neutrinos is predicted to per cent-level accuracy, out to $k=10 \,{ h}\,{\rm Mpc}^{-1}$. We find that refining the prescriptions for the halo properties using N-body simulations improves the recovered accuracy to better than 1 per cent. This paper serves as another demonstration for how the halo model reaction framework, in combination with a single suite of standard Λ cold dark matter (ΛCDM) simulations, can recover per cent-level accurate predictions for beyond ΛCDM matter power spectra, well into the non-linear regime.

scholarly journals On the road to per cent accuracy IV: ReACT – computing the non-linear power spectrum beyond ΛCDM

2020 ◽  
Vol 498 (4) ◽  
pp. 4650-4662
Author(s):  
Benjamin Bose ◽  
Matteo Cataneo ◽  
Tilman Tröster ◽  
Qianli Xia ◽  
Catherine Heymans ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Computational Modelling ◽  
Power Spectra ◽  
Gravity Models ◽  
Parameter Inference ◽  
The Public ◽  
The Road ◽  
Non Linear ◽  
On The Road

ABSTRACT To effectively exploit large-scale structure surveys, we depend on accurate and reliable predictions of non-linear cosmological structure formation. Tools for efficient and comprehensive computational modelling are therefore essential to perform cosmological parameter inference analyses. We present the public software package ReACT, demonstrating its capability for the fast and accurate calculation of non-linear power spectra from non-standard physics. We showcase ReACT through a series of analyses on the DGP and f(R) gravity models, adopting LSST-like cosmic shear power spectra. Accurate non-linear modelling with ReACT has the potential to more than double LSST’s constraining power on the f(R) parameter, in contrast to an analysis that is limited to the quasi-linear regime. We find that ReACT is sufficiently robust for the inference of consistent constraints on theories beyond ΛCDM for current and ongoing surveys. With further improvement, particularly in terms of the accuracy of the non-linear ΛCDM power spectrum, ReACT can, in principle, meet the accuracy requirements for future surveys such as Euclid and LSST.

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 Massive neutrinos and the non-linear matter power spectrum

2012 ◽  
Vol 420 (3) ◽  
pp. 2551-2561 ◽  
Author(s):  
Simeon Bird ◽  
Matteo Viel ◽  
Martin G. Haehnelt
Keyword(s):  
Power Spectrum ◽  
Matter Power Spectrum ◽  
Non Linear ◽  
Massive Neutrinos

scholarly journals Exploring the effects of galaxy formation on matter clustering through a library of simulation power spectra

2019 ◽  
Vol 491 (2) ◽  
pp. 2424-2446 ◽  
Author(s):  
Marcel P van Daalen ◽  
Ian G McCarthy ◽  
Joop Schaye
Keyword(s):  
Power Spectrum ◽  
Galaxy Formation ◽  
Large Scale ◽  
Initial Conditions ◽  
Power Spectra ◽  
Relative Difference ◽  
Theoretical Understanding ◽  
Stellar Feedback ◽  
Matter Power Spectrum ◽  
Systems Simulation

ABSTRACT Upcoming weak lensing surveys require a detailed theoretical understanding of the matter power spectrum in order to derive accurate and precise cosmological parameter values. While galaxy formation is known to play an important role, its precise effects are currently unknown. We present a set of 92 matter power spectra from the OWLS, cosmo-OWLS, and BAryons and HAloes of MAssive Systems simulation suites, including different ΛCDM cosmologies, neutrino masses, subgrid prescriptions, and AGN feedback strengths. We conduct a detailed investigation of the dependence of the relative difference between the total matter power spectra in hydrodynamical and collisionless simulations on the effectiveness of stellar and AGN feedback, cosmology, and redshift. The strength of AGN feedback can greatly affect the power on a range of scales, while a lack of stellar feedback can greatly increase the effectiveness of AGN feedback on large scales. We also examine differences in the initial conditions of hydrodynamic and N-body simulations that can lead to an $\sim 1{{\ \rm per\ cent}}$ discrepancy in the large-scale power, and furthermore show our results to be insensitive to cosmic variance. We present an empirical model capable of predicting the effect of galaxy formation on the matter power spectrum at z = 0 to within $1{{\ \rm per\ cent}}$ for $k\lt 1\, h\, \mathrm{Mpc}^{-1}$, given only the mean baryon fraction in galaxy groups. Differences in group baryon fractions can also explain the quantitative disagreement between predictions from the literature. All total and dark matter only power spectra in this library will be made publicly available at powerlib.strw.leidenuniv.nl.

scholarly journals Modelling the large-scale mass density field of the universe as a function of cosmology and baryonic physics

2020 ◽  
Vol 495 (4) ◽  
pp. 4800-4819 ◽  
Author(s):  
Giovanni Aricò ◽  
Raul E Angulo ◽  
Carlos Hernández-Monteagudo ◽  
Sergio Contreras ◽  
Matteo Zennaro ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Mass Density ◽  
Energy Models ◽  
Matter Power Spectrum ◽  
Non Linear ◽  
Massive Neutrinos ◽  
Hydrodynamical Simulations ◽  
The Universe

ABSTRACT We present and test a framework that models the 3D distribution of mass in the universe as a function of cosmological and astrophysical parameters. Our approach combines two different techniques: a rescaling algorithm that modifies the cosmology of gravity-only N-body simulations, and a ‘baryonification’ algorithm that mimics the effects of astrophysical processes induced by baryons, such as star formation and active galactic nuclei (AGN) feedback. We show how this approach can accurately reproduce the effects of baryons on the matter power spectrum of various state-of-the-art hydrodynamical simulations (EAGLE, Illustris, Illustris-TNG, Horizon-AGN, and OWLS, Cosmo-OWLS and BAHAMAS), to better than 1 per cent from very large down to small, highly non-linear, scales ($k\sim 5 \, h\, {\rm Mpc}^{-1}$), and from z = 0 up to z ∼ 2. We highlight that, because of the heavy optimization of our algorithms, we can obtain these predictions for arbitrary baryonic models and cosmology (including massive neutrinos and dynamical dark energy models) with an almost negligible CPU cost. With these tools in hand, we explore the degeneracies between cosmological and astrophysical parameters in the non-linear mass power spectrum. Our findings suggest that after marginalizing over baryonic physics, cosmological constraints inferred from weak gravitational lensing should be moderately degraded.

scholarly journals On the road to percent accuracy V: The non-linear power spectrum beyond ΛCDM with massive neutrinos and baryonic feedback

2021 ◽  
Author(s):  
Benjamin Bose ◽  
Bill S Wright ◽  
Matteo Cataneo ◽  
Alkistis Pourtsidou ◽  
Carlo Giocoli ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Percent Level ◽  
Linear Structure ◽  
Model Reaction ◽  
Massive Neutrino ◽  
Structure Information ◽  
Non Linear ◽  
Massive Neutrinos ◽  
On The Road ◽  
Hydrodynamical Simulations

Abstract In the context of forthcoming galaxy surveys, to ensure unbiased constraints on cosmology and gravity when using non-linear structure information, percent-level accuracy is required when modelling the power spectrum. This calls for frameworks that can accurately capture the relevant physical effects, while allowing for deviations from ΛCDM. Massive neutrino and baryonic physics are two of the most relevant such effects. We present an integration of the halo model reaction frameworks for massive neutrinos and beyond-ΛCDM cosmologies. The integrated halo model reaction, combined with a pseudo power spectrum modelled by HMCode2020 is then compared against N-body simulations that include both massive neutrinos and an f(R) modification to gravity. We find that the framework is 4 per cent accurate down to at least k ≈ 3 h Mpc−1 for a modification to gravity of |fR0| ≤ 10−5 and for the total neutrino mass Mν ≡ ∑mν ≤ 0.15 eV. We also find that the framework is 4 per cent consistent with EuclidEmulator2 as well as the Bacco emulator for most of the considered νwCDM cosmologies down to at least k ≈ 3 h Mpc−1. Finally, we compare against hydrodynamical simulations employing HMCode2020’s baryonic feedback modelling on top of the halo model reaction. For νΛCDM cosmologies we find 2 per cent accuracy for Mν ≤ 0.48 eV down to at least k ≈ 5h Mpc−1. Similar accuracy is found when comparing to νwCDM hydrodynamical simulations with Mν = 0.06 eV. This offers the first non-linear, theoretically general means of accurately including massive neutrinos for beyond-ΛCDM cosmologies, and further suggests that baryonic, massive neutrino and dark energy physics can be reliably modelled independently.

scholarly journals The anisotropy of the power spectrum in periodic cosmological simulations

2021 ◽  
Vol 503 (4) ◽  
pp. 5638-5645
Author(s):  
Gábor Rácz ◽  
István Szapudi ◽  
István Csabai ◽  
László Dobos
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Power Spectra ◽  
Cosmological Simulations ◽  
Spherical Collapse ◽  
Lower Amplitude ◽  
Hydrodynamical Simulations

ABSTRACT The classical gravitational force on a torus is anisotropic and always lower than Newton’s 1/r2 law. We demonstrate the effects of periodicity in dark matter only N-body simulations of spherical collapse and standard Lambda cold dark matter (ΛCDM) initial conditions. Periodic boundary conditions cause an overall negative and anisotropic bias in cosmological simulations of cosmic structure formation. The lower amplitude of power spectra of small periodic simulations is a consequence of the missing large-scale modes and the equally important smaller periodic forces. The effect is most significant when the largest mildly non-linear scales are comparable to the linear size of the simulation box, as often is the case for high-resolution hydrodynamical simulations. Spherical collapse morphs into a shape similar to an octahedron. The anisotropic growth distorts the large-scale ΛCDM dark matter structures. We introduce the direction-dependent power spectrum invariant under the octahedral group of the simulation volume and show that the results break spherical symmetry.

scholarly journals Kinetic field theory: Non-linear cosmic power spectra in the mean-field approximation

2021 ◽  
Vol 10 (6) ◽  
Author(s):  
Matthias Bartelmann ◽  
Johannes Dombrowski ◽  
Sara Konrad ◽  
Elena Kozlikin ◽  
Robert Lilow ◽  
...  
Keyword(s):  
Field Theory ◽  
Power Spectrum ◽  
Mean Field ◽  
Power Spectra ◽  
Field Approximation ◽  
Density Fluctuations ◽  
Mean Field Approximation ◽  
Non Linear ◽  
Two Parameters ◽  
Kinetic Field

We use the recently developed Kinetic Field Theory (KFT) for cosmic structure formation to show how non-linear power spectra for cosmic density fluctuations can be calculated in a mean-field approximation to the particle interactions. Our main result is a simple, closed and analytic, approximate expression for this power spectrum. This expression has two parameters characterising non-linear structure growth which can be calibrated within KFT itself. Using this self-calibration, the non-linear power spectrum agrees with results obtained from numerical simulations to within typically \lesssim10\,\%≲10% up to wave numbers k\lesssim10\,h\,\mathrm{Mpc}^{-1}k≲10hMpc−1 at redshift z = 0z=0. Adjusting the two parameters to optimise agreement with numerical simulations, the relative difference to numerical results shrinks to typically \lesssim 5\,\%≲5%. As part of the derivation of our mean-field approximation, we show that the effective interaction potential between dark-matter particles relative to Zel’dovich trajectories is sourced by non-linear cosmic density fluctuations only, and is approximately of Yukawa rather than Newtonian shape.

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