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 Gravitational theory of cosmology, galaxies and galaxy clusters

2020 ◽  
Vol 80 (10) ◽  
Author(s):  
J. W. Moffat
Keyword(s):  
Power Spectrum ◽  
Galaxy Clusters ◽  
Degrees Of Freedom ◽  
Galaxy Cluster ◽  
Gravitational Theory ◽  
Baryon Density ◽  
Late Time ◽  
Matter Power Spectrum ◽  
The Galaxy ◽  
Parameter Values

AbstractA modified gravitational theory explains early universe and late time cosmology, galaxy and galaxy cluster dynamics. The modified gravity (MOG) theory extends general relativity (GR) by three extra degrees of freedom: a scalar field G, enhancing the strength of the Newtonian gravitational constant $$G_N$$ G N , a gravitational, spin 1 vector graviton field $$\phi _\mu $$ ϕ μ , and the effective mass $$\mu $$ μ of the ultralight spin 1 graviton. For $$t < t_\mathrm{rec}$$ t < t rec , where $$t_\mathrm{rec}$$ t rec denotes the time of recombination and re-ionization, the density of the vector graviton $$\rho _\phi > \rho _b$$ ρ ϕ > ρ b , where $$\rho _b$$ ρ b is the density of baryons, while for $$t > t_\mathrm{rec}$$ t > t rec we have $$\rho _b > \rho _\phi $$ ρ b > ρ ϕ . The matter density is parameterized by $$\Omega _M=\Omega _b+\Omega _\phi +\Omega _r$$ Ω M = Ω b + Ω ϕ + Ω r where $$\Omega _r=\Omega _\gamma +\Omega _\nu $$ Ω r = Ω γ + Ω ν . For the cosmological parameter values obtained by the Planck Collaboration, the CMB acoustical oscillation power spectrum, polarization and lensing data can be fitted as in the $$\Lambda $$ Λ CDM model. When the baryon density $$\rho _b$$ ρ b dominates the late time universe, MOG explains galaxy rotation curves, the dynamics of galaxy clusters, galaxy lensing and the galaxy clusters matter power spectrum without dominant dark matter.

scholarly journals Clustering in massive neutrino cosmologies via Eulerian Perturbation Theory

2021 ◽  
Vol 2021 (11) ◽  
pp. 028
Author(s):  
Alejandro Aviles ◽  
Arka Banerjee ◽  
Gustavo Niz ◽  
Zachary Slepian
Keyword(s):  
Perturbation Theory ◽  
Power Spectrum ◽  
Effective Field ◽  
Tree Level ◽  
Accurate Approximation ◽  
Bias Parameter ◽  
Wave Numbers ◽  
Massive Neutrinos ◽  
Correct Estimation ◽  
The One

Abstract We introduce an Eulerian Perturbation Theory to study the clustering of tracers for cosmologies in the presence of massive neutrinos. Our approach is based on mapping recently-obtained Lagrangian Perturbation Theory results to the Eulerian framework. We add Effective Field Theory counterterms, IR-resummations and a biasing scheme to compute the one-loop redshift-space power spectrum. To assess our predictions, we compare the power spectrum multipoles against synthetic halo catalogues from the QUIJOTE simulations, finding excellent agreement on scales k ≲ 0.25 h Mpc-1. One can obtain the same fitting accuracy using higher wave-numbers, but then the theory fails to give a correct estimation of the linear bias parameter. We further discuss the implications for the tree-level bispectrum. Finally, calculating loop corrections is computationally costly, hence we derive an accurate approximation wherein we retain only the main features of the kernels, as produced by changes to the growth rate. As a result, we show how FFTLog methods can be used to further accelerate the loop computations with these reduced kernels.

scholarly journals Generating approximate halo catalogues for blind challenges in precision cosmology

2019 ◽  
Vol 485 (2) ◽  
pp. 2407-2416 ◽  
Author(s):  
Lehman H Garrison ◽  
Daniel J Eisenstein
Keyword(s):  
Dark Matter ◽  
Transfer Function ◽  
Power Spectrum ◽  
High Precision ◽  
Real Space ◽  
Dark Matter Halo ◽  
The Real ◽  
The Galaxy ◽  
Similar Accuracy ◽  
Better Than

ABSTRACT We present a method for generating suites of dark matter halo catalogues with only a few N-body simulations, focusing on making small changes to the underlying cosmology of a simulation with high precision. In the context of blind challenges, this allows us to re-use a simulation by giving it a new cosmology after the original cosmology is revealed. Starting with full N-body realizations of an original cosmology and a target cosmology, we fit a transfer function that displaces haloes in the original so that the galaxy/HOD power spectrum matches that of the target cosmology. This measured transfer function can then be applied to a new realization of the original cosmology to create a new realization of the target cosmology. For a 1 per cent change in σ8, we achieve 0.1 per cent accuracy to $k = 1\, h\, \mathrm{Mpc}^{-1}$ in the real-space power spectrum; this degrades to 0.3 per cent when the transfer function is applied to a new realization. We achieve similar accuracy in the redshift-space monopole and quadrupole. In all cases, the result is better than the sample variance of our $1.1\, h^{-1}\, \mathrm{Gpc}$ simulation boxes.

scholarly journals Simulating galaxy formation in f(R) modified gravity: matter, halo, and galaxy statistics

2019 ◽  
Vol 490 (2) ◽  
pp. 2507-2520 ◽  
Author(s):  
Christian Arnold ◽  
Baojiu Li
Keyword(s):  
Correlation Function ◽  
Power Spectrum ◽  
Galaxy Formation ◽  
Mass Function ◽  
Back Reaction ◽  
Satellite Galaxy ◽  
Matter Power Spectrum ◽  
Hydrodynamical Simulation ◽  
The Galaxy ◽  
Galaxy Count

ABSTRACT We present an analysis of the matter, halo, and galaxy clustering in f(R)-gravity employing the SHYBONE full-physics hydrodynamical simulation suite. Our analysis focuses on the interplay between baryonic feedback and f(R)-gravity in the matter power spectrum, the matter and halo correlation functions, the halo and galaxy–host–halo mass function, the subhalo and satellite–galaxy count, and the correlation function of the stars in our simulations. Our studies of the matter power spectrum in full-physics simulations in f(R)-gravity show that it will be very difficult to derive accurate fitting formulae for the power spectrum enhancement in f(R)-gravity which include baryonic effects. We find that the enhancement of the halo mass function due to f(R)-gravity and its suppression due to feedback effects do not show significant back-reaction effects and can thus be estimated from independent general relativity-hydro and f(R) dark matter only simulations. Our simulations furthermore show that the number of subhaloes and satellite-galaxies per halo is not significantly affected by f(R)-gravity. Low-mass haloes are nevertheless more likely to be populated by galaxies in f(R)-gravity. This suppresses the clustering of stars and the galaxy correlation function in the theory compared to standard cosmology.

scholarly journals Cosmological parameters from the likelihood analysis of the galaxy power spectrum and bispectrum in real space

2021 ◽  
Vol 2021 (11) ◽  
pp. 038
Author(s):  
Andrea Oddo ◽  
Federico Rizzo ◽  
Emiliano Sefusatti ◽  
Cristiano Porciani ◽  
Pierluigi Monaco
Keyword(s):  
Power Spectrum ◽  
Cosmological Parameters ◽  
Deviance Information Criterion ◽  
Information Criterion ◽  
Real Space ◽  
Tree Level ◽  
Large Set ◽  
Cross Covariance ◽  
Likelihood Analysis ◽  
The Galaxy

Abstract We present a joint likelihood analysis of the halo power spectrum and bispectrum in real space. We take advantage of a large set of numerical simulations and of an even larger set of halo mock catalogs to provide a robust estimate of the covariance properties. We derive constraints on bias and cosmological parameters assuming a theoretical model from perturbation theory at one-loop for the power spectrum and tree-level for the bispectrum. By means of the Deviance Information Criterion, we select a reference bias model dependent on seven parameters that can describe the data up to k max,P = 0.3 h Mpc-1 for the power spectrum and k max,B = 0.09 h Mpc-1 for the bispectrum at redshift z = 1. This model is able to accurately recover three selected cosmological parameters even for the rather extreme total simulation volume of 1000h -3 Gpc3. With the same tools, we study how relations among bias parameters can improve the fit while reducing the parameter space. In addition, we compare common approximations to the covariance matrix against the full covariance estimated from the mocks, and quantify the (non-negligible) effect of ignoring the cross-covariance between the two statistics. Finally, we explore different selection criteria for the triangular configurations to include in the analysis, showing that excluding nearly equilateral triangles rather than simply imposing a fixed maximum k max,B on all triangle sides can lead to a better exploitation of the information contained in the bispectrum.

scholarly journals Gravitational Fluctuations as an Alternative to Inflation II. CMB Angular Power Spectrum

2019 ◽  
Author(s):  
Herbert W. Hamber ◽  
Lu Heng Sunny Yu
Keyword(s):  
Power Spectrum ◽  
Power Spectra ◽  
Angular Spectrum ◽  
Scalar Fields ◽  
Data Sets ◽  
Angular Power Spectrum ◽  
Fundamental Parameters ◽  
Matter Power Spectrum ◽  
The Galaxy ◽  
Cosmological Data

Power spectra always play an important role in the theory of inflation. In particular, the ability to reproduce the galaxy matter power spectrum $ P(k) $ and the CMB temperature angular power spectrum $ C_l $’s to high accuracy is often considered a triumph of inflation. In our previous work, we presented an alternative explanation for the matter power spectrum based on nonperturbative quantum field-theoretical methods applied to Einstein’s gravity, instead of inflation models based on scalar fields. In this work, we review the basic concepts and provide further in-depth investigations. We first update the analysis with more recent data sets and error analysis, and then extend our predictions to the CMB angular spectrum coefficients $ C_l $, which we did not consider previously. Then we investigate further the potential freedoms and uncertainties associated with the fundamental parameters that are part of this picture, and show how recent cosmological data provides significant constraints on these quantities. Overall, we find good general consistency between theory and data, even potentially favoring the gravitationally-motivated picture at the largest scales. We summarize our results by outlining how this picture can be tested in the near future with increasingly accurate astrophysical measurements.

scholarly journals Dark Energy Survey Year 1 results: measurement of the galaxy angular power spectrum

2019 ◽  
Vol 487 (3) ◽  
pp. 3870-3883 ◽  
Author(s):  
H Camacho ◽  
N Kokron ◽  
F Andrade-Oliveira ◽  
R Rosenfeld ◽  
M Lima ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Covariance Matrix ◽  
Goodness Of Fit ◽  
Effective Area ◽  
Real Space ◽  
Harmonic Space ◽  
Angular Power Spectrum ◽  
Space Analysis ◽  
The Galaxy ◽  
The Impact

ABSTRACT We use data from the first-year observations of the DES collaboration to measure the galaxy angular power spectrum (APS), and search for its BAO feature. We test our methodology in a sample of 1800 DES Y1-like mock catalogues. We use the pseudo-Cℓ method to estimate the APS and the mock catalogues to estimate its covariance matrix. We use templates to model the measured spectra and estimate template parameters firstly from the Cℓ’s of the mocks using two different methods, a maximum likelihood estimator and a Markov Chain Monte Carlo, finding consistent results with a good reduced χ2. Robustness tests are performed to estimate the impact of different choices of settings used in our analysis. Finally, we apply our method to a galaxy sample constructed from DES Y1 data specifically for LSS studies. This catalogue comprises galaxies within an effective area of 1318 deg2 and 0.6 &lt; z &lt; 1.0. We find that the DES Y1 data favour a model with BAO at the $2.6 \sigma$ C.L. However, the goodness of fit is somewhat poor, with χ2/(d.o.f.)  = 1.49. We identify a possible cause showing that using a theoretical covariance matrix obtained from Cℓ’s that are better adjusted to data results in an improved value of χ2/(dof)  = 1.36 which is similar to the value obtained with the real-space analysis. Our results correspond to a distance measurement of DA(zeff = 0.81)/rd = 10.65 ± 0.49, consistent with the main DES BAO findings. This is a companion paper to the main DES BAO article showing the details of the harmonic space analysis.

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