scholarly journals Breaking cosmic degeneracies: Disentangling neutrinos and modified gravity with kinematic information

2019 ◽  
Vol 629 ◽  
pp. A46 ◽  
Author(s):  
Steffen Hagstotz ◽  
Max Gronke ◽  
David F. Mota ◽  
Marco Baldi
Keyword(s):  
Growth Rate ◽  
Power Spectrum ◽  
Modified Gravity ◽  
Large Scale ◽  
Density Fluctuations ◽  
Gravity Models ◽  
Neutrino Masses ◽  
Matter Power Spectrum ◽  
Massive Neutrinos ◽  
Kinematic Information

Searches for modified gravity in the large-scale structure try to detect the enhanced amplitude of density fluctuations caused by the fifth force present in many of these theories. Neutrinos, on the other hand, suppress structure growth below their free-streaming length. Both effects take place on comparable scales, and uncertainty in the neutrino mass leads to a degeneracy with modified gravity parameters for probes that are measuring the amplitude of the matter power spectrum. We explore the possibility to break the degeneracy between modified gravity and neutrino effects in the growth of structures by considering kinematic information related to either the growth rate on large scales or the virial velocities inside of collapsed structures. In order to study the degeneracy up to fully non-linear scales, we employ a suite of N-body simulations including both f(R) modified gravity and massive neutrinos. Our results indicate that velocity information provides an excellent tool to distinguish massive neutrinos from modified gravity. Models with different values of neutrino masses and modified gravity parameters possessing a comparable matter power spectrum at a given time have different growth rates. This leaves imprints in the velocity divergence, which is therefore better suited than the amplitude of density fluctuations to tell the models apart. In such models with a power spectrum comparable to ΛCDM today, the growth rate is strictly enhanced. We also find the velocity dispersion of virialised clusters to be well suited to constrain deviations from general relativity without being affected by the uncertainty in the sum of neutrino masses.

scholarly journals Constraints on neutrino masses from the study of the nearby large-scale structure and galaxy cluster counts

2016 ◽  
Vol 31 (21) ◽  
pp. 1640008 ◽  
Author(s):  
Hans Böhringer ◽  
Gayoung Chon
Keyword(s):  
Large Scale ◽  
Cosmological Parameters ◽  
Large Scale Structure ◽  
Matter Density ◽  
Density Fluctuations ◽  
Scale Structure ◽  
Neutrino Masses ◽  
Microwave Background ◽  
X Ray ◽  
Massive Neutrinos

The high precision measurements of the cosmic microwave background by the Planck survey yielded tight constraints on cosmological parameters and the statistics of the density fluctuations at the time of recombination. This provides the means for a critical study of structure formation in the Universe by comparing the microwave background results with present epoch measurements of the cosmic large-scale structure. It can reveal subtle effects such as how different forms of Dark Matter may modify structure growth. Currently most interesting is the damping effect of structure growth by massive neutrinos. Different observations of low redshift matter density fluctuations provided evidence for a signature of massive neutrinos. Here we discuss the study of the cosmic large-scale structure with a complete sample of nearby, X-ray luminous clusters from our REFLEX cluster survey. From the observed X-ray luminosity function and its reproduction for different cosmological models, we obtain tight constraints on the cosmological parameters describing the matter density, [Formula: see text], and the density fluctuation amplitude, [Formula: see text]. A comparison of these constraints with the Planck results shows a discrepancy in the framework of a pure [Formula: see text]CDM model, but the results can be reconciled, if we allow for a neutrino mass in the range of 0.17 eV to 0.7 eV. Also some others, but not all of the observations of the nearby large-scale structure provide evidence or trends for signatures of massive neutrinos. With further improvement in the systematics and future survey projects, these indications will develop into a definitive measurement of neutrino masses.

f(R) COSMOLOGY AND MASSIVE NEUTRINOS

2012 ◽  
Vol 10 ◽  
pp. 35-42 ◽  
Author(s):  
HAYATO MOTOHASHI ◽  
ALEXEI A. STAROBINSKY ◽  
JUN'ICHI YOKOYAMA
Keyword(s):  
Equation Of State ◽  
Power Spectrum ◽  
State Parameter ◽  
Density Fluctuations ◽  
Matter Power Spectrum ◽  
Small Scales ◽  
Λcdm Model ◽  
Equation Of State Parameter ◽  
Massive Neutrinos ◽  
Anomalous Growth

f(R) gravity provides viable cosmology alternative to the ΛCDM model. We discuss the effect of massive neutrinos on matter power spectrum in this theory, to show that the anomalous growth of density fluctuations on small scales due to the scalaron force can be compensated by free streaming of neutrinos. As a result, models which predict observable deviation of the equation-of-state parameter w DE from w DE = -1 may be reconciled with observations of matter clustering if the total neutrino mass is O(0.5 eV ).

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 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 Clustering and redshift-space distortions in modified gravity models with massive neutrinos

2019 ◽  
Vol 488 (2) ◽  
pp. 1987-2000 ◽  
Author(s):  
Jorge Enrique García-Farieta ◽  
Federico Marulli ◽  
Alfonso Veropalumbo ◽  
Lauro Moscardini ◽  
Rigoberto A Casas-Miranda ◽  
...  
Keyword(s):  
Dark Matter ◽  
Modified Gravity ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Gravity Models ◽  
Linear Growth Rate ◽  
Λcdm Model ◽  
Point Correlation ◽  
Massive Neutrinos ◽  
Modified Gravity Models

Abstract Modified gravity and massive neutrino cosmologies are two of the most interesting scenarios that have been recently explored to account for possible observational deviations from the concordance Λ cold dark matter (ΛCDM) model. In this context, we investigated the large-scale structure of the Universe by exploiting the dustgrain-pathfinder simulations that implement, simultaneously, the effects of f(R) gravity and massive neutrinos. To study the possibility of breaking the degeneracy between these two effects, we analysed the redshift-space distortions in the clustering of dark matter haloes at different redshifts. Specifically, we focused on the monopole and quadrupole of the two-point correlation function, both in real and redshift space. The deviations with respect to ΛCDM model have been quantified in terms of the linear growth rate parameter. We found that redshift-space distortions provide a powerful probe to discriminate between ΛCDM and modified gravity models, especially at high redshifts (z ≳ 1), even in the presence of massive neutrinos.

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.

scholarly journals Cosmological model parameter dependence of the matter power spectrum covariance from the DEUS-PUR Cosmo simulations

2020 ◽  
Vol 500 (2) ◽  
pp. 2532-2542
Author(s):  
Linda Blot ◽  
Pier-Stefano Corasaniti ◽  
Yann Rasera ◽  
Shankar Agarwal
Keyword(s):  
Dark Energy ◽  
Power Spectrum ◽  
Cold Dark Matter ◽  
Matter Density ◽  
Density Fluctuations ◽  
Matrix Analysis ◽  
Model Parameter ◽  
Matter Power Spectrum ◽  
Non Gaussian ◽  
The Impact

ABSTRACT Future galaxy surveys will provide accurate measurements of the matter power spectrum across an unprecedented range of scales and redshifts. The analysis of these data will require one to accurately model the imprint of non-linearities of the matter density field. In particular, these induce a non-Gaussian contribution to the data covariance that needs to be properly taken into account to realize unbiased cosmological parameter inference analyses. Here, we study the cosmological dependence of the matter power spectrum covariance using a dedicated suite of N-body simulations, the Dark Energy Universe Simulation–Parallel Universe Runs (DEUS-PUR) Cosmo. These consist of 512 realizations for 10 different cosmologies where we vary the matter density Ωm, the amplitude of density fluctuations σ8, the reduced Hubble parameter h, and a constant dark energy equation of state w by approximately $10{{\ \rm per\ cent}}$. We use these data to evaluate the first and second derivatives of the power spectrum covariance with respect to a fiducial Λ-cold dark matter cosmology. We find that the variations can be as large as $150{{\ \rm per\ cent}}$ depending on the scale, redshift, and model parameter considered. By performing a Fisher matrix analysis we explore the impact of different choices in modelling the cosmological dependence of the covariance. Our results suggest that fixing the covariance to a fiducial cosmology can significantly affect the recovered parameter errors and that modelling the cosmological dependence of the variance while keeping the correlation coefficient fixed can alleviate the impact of this effect.

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.

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