scholarly journals Accelerating Large-Scale-Structure data analyses by emulating Boltzmann solvers and Lagrangian Perturbation Theory

2021 ◽  
Vol 1 ◽  
pp. 152
Author(s):  
Giovanni Arico' ◽  
Raul Angulo ◽  
Matteo Zennaro
Keyword(s):  
Perturbation Theory ◽  
Power Spectrum ◽  
Large Scale ◽  
Theoretical Models ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Matter Power Spectrum ◽  
Linear Spectrum ◽  
Massive Neutrinos ◽  
Cold Matter

The linear matter power spectrum is an essential ingredient in all theoretical models for interpreting large-scale-structure observables. Although Boltzmann codes such as CLASS or CAMB are very efficient at computing the linear spectrum, the analysis of data usually requires 104-106 evaluations, which means this task can be the most computationally expensive aspect of data analysis. Here, we address this problem by building a neural network emulator that provides the linear theory (total and cold) matter power spectrum in about one millisecond with ≈0.2%(0.5%) accuracy over redshifts z ≤ 3 (z ≤ 9), and scales10-4 ≤ k [h Mpc-1] < 50. We train this emulator with more than 200,000 measurements, spanning a broad cosmological parameter space that includes massive neutrinos and dynamical dark energy. We show that the parameter range and accuracy of our emulator is enough to get unbiased cosmological constraints in the analysis of a Euclid-like weak lensing survey. Complementing this emulator, we train 15 other emulators for the cross-spectra of various linear fields in Eulerian space, as predicted by 2nd-order Lagrangian Perturbation theory, which can be used to accelerate perturbative bias descriptions of galaxy clustering. Our emulators are specially designed to be used in combination with emulators for the nonlinear matter power spectrum and for baryonic effects, all of which are publicly available at http://www.dipc.org/bacco.

Cosmological probes of modified gravity: the nonlinear regime

2011 ◽  
Vol 369 (1957) ◽  
pp. 5068-5080 ◽  
Author(s):  
Fabian Schmidt
Keyword(s):  
Power Spectrum ◽  
Modified Gravity ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Nonlinear Regime ◽  
Matter Power Spectrum ◽  
Massive Halos

We review the effects of modified gravity on large-scale structure in the nonlinear regime, focusing on f ( R ) gravity and the Dvali–Gabadadze–Porrati model, for which full N -body simulations have been performed. In particular, we discuss the abundance of massive halos, the nonlinear matter power spectrum and the dynamics within clusters and galaxies, with particular emphasis on the screening mechanisms present in these models.

scholarly journals Non-Gaussian covariance of the matter power spectrum in the effective field theory of large scale structure

2016 ◽  
Vol 93 (12) ◽  
Author(s):  
Daniele Bertolini ◽  
Katelin Schutz ◽  
Mikhail P. Solon ◽  
Jonathan R. Walsh ◽  
Kathryn M. Zurek
Keyword(s):  
Field Theory ◽  
Power Spectrum ◽  
Effective Field Theory ◽  
Large Scale ◽  
Large Scale Structure ◽  
Effective Field ◽  
Scale Structure ◽  
Matter Power Spectrum ◽  
Non Gaussian

scholarly journals The bahamas project: effects of a running scalar spectral index on large-scale structure

2020 ◽  
Vol 493 (1) ◽  
pp. 676-697 ◽  
Author(s):  
Sam G Stafford ◽  
Ian G McCarthy ◽  
Robert A Crain ◽  
Jaime Salcido ◽  
Joop Schaye ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Spectral Index ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Mass Relation ◽  
Cluster Number ◽  
The Bahamas ◽  
Matter Power Spectrum ◽  
Scalar Spectral Index

ABSTRACT Recent analyses of the cosmic microwave background (CMB) and the Lyman α forest indicate a mild preference for a deviation from a power-law primordial matter power spectrum (a so-called running). We introduce an extension to the bahamas suite of simulations to explore the effects that a running scalar spectral index has on large-scale structure (LSS), using Planck CMB constraints to initialize the simulations. We focus on five key statistics: (i) the non-linear matter power spectrum (ii) the halo mass function; (iii) the halo two-point autocorrelation function; (iv) total mass halo density profiles; and (v) the halo concentration–mass relation. We find that the matter power spectrum in a Planck-constrained running cosmology is affected on all k-scales examined in this study. These effects on the matter power spectrum should be detectable with upcoming surveys such as LSST and Euclid. A positive running cosmology leads to an increase in the mass of galaxy groups and clusters, with the favoured negative running leading to a decrease in mass of lower mass ($M \lesssim 10^{13} \, \textrm{M}_{\odot }$) haloes, but an increase for the most massive ($M \gtrsim 10^{13} \, \textrm{M}_{\odot }$) haloes. Changes in the mass are generally confined to $5\rm {-}10{{\ \rm per\ cent}}$ which, while not insignificant, cannot by itself reconcile the claimed tension between the primary CMB and cluster number counts. We also demonstrate that the observed effects on LSS due to a running scalar spectral index are separable from those of baryonic effects to typically a few per cent precision.

scholarly journals Using the Marked Power Spectrum to Detect the Signature of Neutrinos in Large-Scale Structure

2021 ◽  
Vol 126 (1) ◽  
Author(s):  
Elena Massara ◽  
Francisco Villaescusa-Navarro ◽  
Shirley Ho ◽  
Neal Dalal ◽  
David N. Spergel
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure

scholarly journals Anti-symmetric clustering signals in the observed power spectrum

2021 ◽  
Vol 2021 (12) ◽  
pp. 003
Author(s):  
José Fonseca ◽  
Chris Clarkson
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Euler Equation ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Power Spectra ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Signal To Noise ◽  
Peculiar Velocities

Abstract In this paper, we study how to directly measure the effect of peculiar velocities in the observed angular power spectra. We do this by constructing a new anti-symmetric estimator of Large Scale Structure using different dark matter tracers. We show that the Doppler term is the major component of our estimator and we show that we can measure it with a signal-to-noise ratio up to ∼ 50 using a futuristic SKAO HI galaxy survey. We demonstrate the utility of this estimator by using it to provide constraints on the Euler equation.

scholarly journals Estimates for the impact of ultraviolet background fluctuations on galaxy clustering measurements

2019 ◽  
Vol 485 (4) ◽  
pp. 5059-5072 ◽  
Author(s):  
Phoebe Upton Sanderbeck ◽  
Vid Iršič ◽  
Matthew McQuinn ◽  
Avery Meiksin
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Galaxy Surveys ◽  
Intensity Mapping ◽  
Redshift Galaxy ◽  
Halo Gas ◽  
The Cost ◽  
The Impact

ABSTRACT Spatial fluctuations in ultraviolet backgrounds can subtly modulate the distribution of extragalactic sources, a potential signal and systematic for large-scale structure surveys. While this modulation has been shown to be significant for 3D Ly α forest surveys, its relevance for other large-scale structure probes has been hardly explored, despite being the only astrophysical process that likely can affect clustering measurements on the scales of ≳Mpc. We estimate that the background fluctuations, modulating the amount of H i, have a fractional effect of (0.03–0.3) × (k/[10−2 Mpc−1])−1 on the power spectrum of 21 cm intensity maps at z = 1–3. We find a smaller effect for H α and Ly α intensity mapping surveys of (0.001–0.1) × (k/[10−2 Mpc−1])−1 and even smaller effect for more traditional surveys that correlate the positions of individual H α or Ly α emitters. We also estimate the effect of backgrounds on low-redshift galaxy surveys in general based on a simple model in which background fluctuations modulate the rate halo gas cools, modulating star formation: We estimate a maximum fractional effect on the power of ∼0.01 (k/[10−2 Mpc−1])−1 at z = 1. We compare sizes of these imprints to cosmological parameter benchmarks for the next generation of redshift surveys: We find that ionizing backgrounds could result in a bias on the squeezed triangle non-Gaussianity parameter fNL that can be larger than unity for power spectrum measurements with a SPHEREx-like galaxy survey, and typical values of intensity bias. Marginalizing over a shape of the form k−1PL, where PL is the linear matter power spectrum, removes much of this bias at the cost of ${\approx } 40{{\ \rm per\ cent}}$ larger statistical errors.

scholarly journals Power spectrum response of large-scale structure in 1D and in 3D: tests of prescriptions for post-collapse dynamics

2020 ◽  
Vol 499 (2) ◽  
pp. 1769-1787
Author(s):  
Anaëlle Halle ◽  
Takahiro Nishimichi ◽  
Atsushi Taruya ◽  
Stéphane Colombi ◽  
Francis Bernardeau
Keyword(s):  
Power Spectrum ◽  
Response Function ◽  
Large Scale ◽  
Initial Conditions ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Adaptive Smoothing ◽  
Single Stream ◽  
Non Linear ◽  
Spectrum Response

ABSTRACT The power spectrum response function of the large-scale structure of the Universe describes how the evolved power spectrum is modified by a small change in initial power through non-linear mode coupling of gravitational evolution. It was previously found that the response function for the coupling from small to large scales is strongly suppressed in amplitude, especially at late times, compared to predictions from perturbation theory (PT) based on the single-stream approximation. One obvious explanation for this is that PT fails to describe the dynamics beyond shell crossing. We test this idea by comparing measurements in N-body simulations to prescriptions based on PT but augmented with adaptive smoothing to account for the formation of non-linear structures of various sizes in the multistream regime. We first start with one-dimensional (1D) cosmology, where the Zel’dovich approximation provides the exact solution in the single-stream regime. Similarly to the three-dimensional (3D) case, the response function of the large-scale modes exhibits a strong suppression in amplitude at small scales that cannot be explained by the Zel’dovich solution alone. However, by performing adaptive smoothing of initial conditions to identify haloes of different sizes and solving approximately post-collapse dynamics in the three-stream regime, agreement between theory and simulations drastically improves. We extend our analyses to the 3D case using the pinocchio algorithm, in which similar adaptive smoothing is implemented on the Lagrangian PT fields to identify haloes and is combined with a spherical halo prescription to account for post-collapse dynamics. Again, a suppression is found in the coupling between small- and large-scale modes and the agreement with simulations is improved.

scholarly journals Possible Detection of Baryonic Fluctuations in the Large‐Scale Structure Power Spectrum

2001 ◽  
Vol 555 (1) ◽  
pp. 68-73 ◽  
Author(s):  
Christopher J. Miller ◽  
Robert C. Nichol ◽  
David J. Batuski
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure
Sign in / Sign up

Export Citation Format

Share Document