scholarly journals Constraining degenerate higher-order scalar-tensor theories with linear growth of matter density fluctuations

2019 ◽  
Vol 99 (10) ◽  
Author(s):  
Shin’ichi Hirano ◽  
Tsutomu Kobayashi ◽  
Daisuke Yamauchi ◽  
Shuichiro Yokoyama
Keyword(s):  
Linear Growth ◽  
Higher Order ◽  
Matter Density ◽  
Density Fluctuations

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.

Supernova neutrino burst as a probe of shock waves and matter density fluctuations

IFAE 2006 ◽  
2007 ◽  
pp. 313-316
Author(s):  
Gian Luigi Fogli ◽  
Eligio Lisi ◽  
Alessandro Mirizzi ◽  
Daniele Montanino
Keyword(s):  
Shock Waves ◽  
Matter Density ◽  
Density Fluctuations ◽  
Supernova Neutrino

scholarly journals Borexino as a test of solar matter density fluctuations

1999 ◽  
Vol 70 (1-3) ◽  
pp. 345-347
Author(s):  
H. Nunokawa ◽  
A. Rossi ◽  
V. Semikoz ◽  
J.W.F. Valle
Keyword(s):  
Matter Density ◽  
Density Fluctuations

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.

scholarly journals Linear Growth of Matter Density Perturbations in Theories

2011 ◽  
Vol 125 (3) ◽  
pp. 603-615 ◽  
Author(s):  
A. De Felice ◽  
T. Suyama
Keyword(s):  
Linear Growth ◽  
Matter Density ◽  
Density Perturbations

PALATINI f(R) COSMOLOGY

2008 ◽  
Vol 23 (17n20) ◽  
pp. 1388-1396 ◽  
Author(s):  
SEOKCHEON LEE
Keyword(s):  
Linear Growth ◽  
Matter Density ◽  
Modified Theories Of Gravity ◽  
Cosmic Expansion ◽  
Energy Models ◽  
Modified Gravity Theories ◽  
Theories Of Gravity ◽  
The Stability ◽  
Cosmic Expansion History ◽  
General Gauge

We investigate the modified gravity theories in terms of the effective dark energy models. We compare the cosmic expansion history and the linear growth in different models. We also study the evolution of linear cosmological perturbations in modified theories of gravity assuming the Palatini formalism. We find the stability of the superhorizon metric evolution depends on models. We also study the matter density fluctuation in the general gauge and show the differential equations in super and sub-horizon scales.

scholarly journals Gravity and the non-linear growth of structure in the Carnegie-Spitzer-IMACS Redshift Survey

2020 ◽  
Vol 494 (2) ◽  
pp. 2628-2640 ◽  
Author(s):  
Daniel D Kelson ◽  
Louis E Abramson ◽  
Andrew J Benson ◽  
Shannon G Patel ◽  
Stephen A Shectman ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Linear Growth ◽  
Real Space ◽  
Density Fluctuations ◽  
Analytic Description ◽  
Newtonian Gravity ◽  
Density Growth ◽  
Non Linear ◽  
Redshift Survey ◽  
Analytic Prediction

ABSTRACT A key obstacle to developing a satisfying theory of galaxy evolution is the difficulty in extending analytic descriptions of early structure formation into full non-linearity, the regime in which galaxy growth occurs. Extant techniques, though powerful, are based on approximate numerical methods whose Monte Carlo-like nature hinders intuition building. Here, we develop a new solution to this problem and its empirical validation. We first derive closed-form analytic expectations for the evolution of fixed percentiles in the real-space cosmic density distribution, averaged over representative volumes observers can track cross-sectionally. Using the Lagrangian forms of the fluid equations, we show that percentiles in δ – the density relative to the median – should grow as $\delta (t)\propto \delta _{0}^{\alpha }\, t^{\beta }$, where α ≡ 2 and β ≡ 2 for Newtonian gravity at epochs after the overdensities transitioned to non-linear growth. We then use 9.5 square degress of Carnegie-Spitzer-IMACS Redshift Survey data to map galaxy environmental densities over 0.2 < z < 1.5 (∼7 Gyr) and infer α = 1.98 ± 0.04 and β = 2.01 ± 0.11 – consistent with our analytic prediction. These findings – enabled by swapping the Eulerian domain of most work on density growth for a Lagrangian approach to real-space volumetric averages – provide some of the strongest evidence that a lognormal distribution of early density fluctuations indeed decoupled from cosmic expansion to grow through gravitational accretion. They also comprise the first exact, analytic description of the non-linear growth of structure extensible to (arbitrarily) low redshift. We hope these results open the door to new modelling of, and insight-building into, galaxy growth and its diversity in cosmological contexts.

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