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 percent accuracy: non-linear reaction of the matter power spectrum to dark energy and modified gravity

2019 ◽  
Vol 488 (2) ◽  
pp. 2121-2142 ◽  
Author(s):  
M Cataneo ◽  
L Lombriser ◽  
C Heymans ◽  
A J Mead ◽  
A Barreira ◽  
...  
Keyword(s):  
Dark Energy ◽  
Power Spectrum ◽  
Modified Gravity ◽  
Cold Dark Matter ◽  
High Signal ◽  
Linear Perturbation ◽  
Matter Power Spectrum ◽  
Wide Range ◽  
Non Linear ◽  
Better Than

ABSTRACT We present a general method to compute the non-linear matter power spectrum for dark energy (DE) and modified gravity scenarios with per cent-level accuracy. By adopting the halo model and non-linear perturbation theory, we predict the reaction of a lambda cold dark matter (ΛCDM) matter power spectrum to the physics of an extended cosmological parameter space. By comparing our predictions to N-body simulations we demonstrate that with no-free parameters we can recover the non-linear matter power spectrum for a wide range of different w0–wa DE models to better than 1 per cent accuracy out to k ≈ 1 $h \,{\rm Mpc}^{-1}$. We obtain a similar performance for both DGP and f(R) gravity, with the non-linear matter power spectrum predicted to better than 3 per cent accuracy over the same range of scales. When including direct measurements of the halo mass function from the simulations, this accuracy improves to 1 per cent. With a single suite of standard ΛCDM N-body simulations, our methodology provides a direct route to constrain a wide range of non-standard extensions to the concordance cosmology in the high signal-to-noise non-linear regime.

scholarly journals f(R) GRAVITY AND ITS COSMOLOGICAL IMPLICATIONS

2011 ◽  
Vol 20 (08) ◽  
pp. 1347-1355 ◽  
Author(s):  
HAYATO MOTOHASHI ◽  
ALEXEI A. STAROBINSKY ◽  
JUN'ICHI YOKOYAMA
Keyword(s):  
Dark Energy ◽  
Power Spectrum ◽  
Growth Index ◽  
Matter Density ◽  
Cosmic Acceleration ◽  
Matter Power Spectrum ◽  
Density Perturbations ◽  
Massive Neutrinos ◽  
The Universe ◽  
Anomalous Growth

We have investigated the evolution of a homogeneous isotropic background of the Universe and inhomogeneous subhorizon matter density perturbations in viable f(R) models of present dark energy and cosmic acceleration analytically and numerically. It is found that viable f(R) models generically exhibit recent crossing of the phantom boundary w DE = -1. Furthermore, it is shown that the growth index of perturbations depends both on time and wavenumber. This anomalous growth may explain properties of the observational matter power spectrum from the SDSS data and can also partially counteract the spectrum suppression by massive neutrinos making larger values of the total sum of neutrino rest-masses possible.

scholarly journals Weak lensing minima and peaks: Cosmological constraints and the impact of baryons

2020 ◽  
Vol 495 (3) ◽  
pp. 2531-2542 ◽  
Author(s):  
William R Coulton ◽  
Jia Liu ◽  
Ian G McCarthy ◽  
Ken Osato
Keyword(s):  
Power Spectrum ◽  
Neutrino Mass ◽  
Matter Density ◽  
Weak Lensing ◽  
Cosmological Constraints ◽  
Credible Intervals ◽  
Hydrodynamical Simulations ◽  
Non Gaussian ◽  
The Impact

ABSTRACT We present a novel statistic to extract cosmological information in weak lensing data: the lensing minima. We also investigate the effect of baryons on cosmological constraints from peak and minimum counts. Using the MassiveNuS simulations, we find that lensing minima are sensitive to non-Gaussian cosmological information and are complementary to the lensing power spectrum and peak counts. For an LSST-like survey, we obtain $95{{\ \rm per\ cent}}$ credible intervals from a combination of lensing minima and peaks that are significantly stronger than from the power spectrum alone, by $44{{\ \rm per\ cent}}$, $11{{\ \rm per\ cent}}$, and $63{{\ \rm per\ cent}}$ for the neutrino mass sum ∑mν, matter density Ωm, and amplitude of fluctuation As, respectively. We explore the effect of baryonic processes on lensing minima and peaks using the hydrodynamical simulations BAHAMAS and Osato15. We find that ignoring baryonic effects would lead to strong (≈4σ) biases in inferences from peak counts, but negligible (≈0.5σ) for minimum counts, suggesting lensing minima are a potentially more robust tool against baryonic effects. Finally, we demonstrate that the biases can in principle be mitigated without significantly degrading cosmological constraints when we model and marginalize the baryonic effects.

scholarly journals Primordial non-Gaussianity without tails – how to measure fNL with the bulk of the density PDF

2020 ◽  
Vol 498 (1) ◽  
pp. 464-483 ◽  
Author(s):  
Oliver Friedrich ◽  
Cora Uhlemann ◽  
Francisco Villaescusa-Navarro ◽  
Tobias Baldauf ◽  
Marc Manera ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Initial Conditions ◽  
Density Fluctuations ◽  
Joint Analysis ◽  
Late Time ◽  
Non Linear ◽  
Free Parameters ◽  
Non Gaussian ◽  
The Impact ◽  
Time Density

ABSTRACT We investigate the possibility to detect primordial non-Gaussianity by analysing the bulk of the probability distribution function (PDF) of late-time cosmic density fluctuations. For this purpose, we devise a new method to predict the impact of general non-Gaussian initial conditions on the late-time density PDF. At redshift z = 1 and for a smoothing scale of 30 Mpc h−1 our predictions agree with the high-resolution Quijote N-body simulations to $\sim 0.2{{\ \rm per\ cent}}$ precision. This is within cosmic variance of a ∼100(Gpc h−1)3 survey volume. When restricting to this 30 Mpc h−1 smoothing scale and to mildly non-linear densities (δ[30 Mpc h−1] ∈ [−0.3, 0.4]) and also marginalizing over potential ignorance of the amplitude of the non-linear power spectrum an analysis of the PDF for such a survey volume can still measure the amplitude of different primordial bispectrum shapes to an accuracy of $\Delta f_{\mathrm{NL}}^{\mathrm{loc}} = \pm 7.4\ ,\ \Delta f_{\mathrm{NL}}^{\mathrm{equi}} = \pm 22.0\ ,\ \Delta f_{\mathrm{NL}}^{\mathrm{ortho}} = \pm 46.0$. When pushing to smaller scales and assuming a joint analysis of the PDF with smoothing radii of 30 and 15 Mpc h−1 (δ[15 Mpc h−1] ∈ [−0.4, 0.5]) this improves to $\Delta f_{\mathrm{NL}}^{\mathrm{loc}} = \pm 3.3\ ,\ \Delta f_{\mathrm{NL}}^{\mathrm{equi}} = \pm 11.0\ ,\ \Delta f_{\mathrm{NL}}^{\mathrm{ortho}} = \pm 17.0$ – even when marginalizing over the non-linear variances at both scales as two free parameters. Especially, such an analysis could simultaneously measure fNL and the amplitude and slope of the non-linear power spectrum. However, at 15 Mpc h−1 our predictions are only accurate to $\lesssim 0.8{{\ \rm per\ cent}}$ for the considered density range. We discuss how this has to be improved in order to push to these small scales and make full use of upcoming surveys with a PDF-based analysis.

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 Impact of relativistic effects on the primordial non-Gaussianity signature in the large-scale clustering of quasars

2020 ◽  
Vol 499 (2) ◽  
pp. 2598-2607
Author(s):  
Mike (Shengbo) Wang ◽  
Florian Beutler ◽  
David Bacon
Keyword(s):  
Dark Energy ◽  
Power Spectrum ◽  
Luminosity Function ◽  
Large Scale ◽  
Relativistic Effects ◽  
Redshift Range ◽  
Cosmological Background ◽  
Relativistic Corrections ◽  
The Galaxy ◽  
The Impact

ABSTRACT Relativistic effects in clustering observations have been shown to introduce scale-dependent corrections to the galaxy overdensity field on large scales, which may hamper the detection of primordial non-Gaussianity fNL through the scale-dependent halo bias. The amplitude of relativistic corrections depends not only on the cosmological background expansion, but also on the redshift evolution and sensitivity to the luminosity threshold of the tracer population being examined, as parametrized by the evolution bias be and magnification bias s. In this work, we propagate luminosity function measurements from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) to be and s for the quasar (QSO) sample, and thereby derive constraints on relativistic corrections to its power spectrum multipoles. Although one could mitigate the impact on the fNL signature by adjusting the redshift range or the luminosity threshold of the tracer sample being considered, we suggest that, for future surveys probing large cosmic volumes, relativistic corrections should be forward modelled from the tracer luminosity function including its uncertainties. This will be important to quasar clustering measurements on scales $k \sim 10^{-3}\, h\, {\rm Mpc}^{-1}$ in upcoming surveys such as the Dark Energy Spectroscopic Instrument (DESI), where relativistic corrections can overwhelm the expected fNL signature at low redshifts z ≲ 1 and become comparable to fNL ≃ 1 in the power spectrum quadrupole at redshifts z ≳ 2.5.

scholarly journals ETHOS – an effective theory of structure formation: formation of the first haloes and their stars

2019 ◽  
Vol 485 (4) ◽  
pp. 5474-5489 ◽  
Author(s):  
Mark R Lovell ◽  
Jesús Zavala ◽  
Mark Vogelsberger
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Dwarf Galaxy ◽  
Mass Scale ◽  
Effective Theory ◽  
Matter Power Spectrum ◽  
Hydrodynamical Simulations ◽  
Stellar Masses

Abstract A cut-off in the linear matter power spectrum at dwarf galaxy scales has been shown to affect the abundance, formation mechanism and age of dwarf haloes, and their galaxies at high and low redshifts. We use hydrodynamical simulations of galaxy formation within the ETHOS framework in a benchmark model that has such a cut-off and that has been shown to be an alternative to the cold dark matter (CDM) model that alleviates its dwarf-scale challenges. We show how galaxies in this model form differently to CDM, on a halo-by-halo basis, at redshifts z ≥ 6. We show that when CDM haloes with masses around the ETHOS half-mode mass scale are resimulated with the ETHOS matter power spectrum, they form with 50 per cent less mass than their CDM counterparts due to their later formation times, yet they retain more of their gas reservoir due to the different behaviour of gas and dark matter during the monolithic collapse of the first haloes in models with a galactic-scale cut-off. As a result, galaxies in ETHOS haloes near the cut-off scale grow rapidly between z = 10 and 6 and by z = 6 end up having very similar stellar masses, higher gas fractions and higher star formation rates relative to their CDM counterparts. We highlight these differences by making predictions for how the number of galaxies with old stellar populations is suppressed in ETHOS for both z = 6 galaxies and for gas-poor Local Group fossil galaxies. Interestingly, we find an age gradient in ETHOS between galaxies that form in high- and low-density environments.

scholarly journals A Model for the Sequence of Elliptical Galaxies

1987 ◽  
Vol 117 ◽  
pp. 367-367
Author(s):  
Rosemary F. G. Wyse ◽  
Bernard J. T. Jones
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Density Fluctuations ◽  
Analytic Approximation ◽  
Non Linear

We present a simple model for the formation of elliptical galaxies, based on a binary clustering hierarchy of dark matter, the chemical enrichment of the gas at each level being controlled by supernovae. The initial conditions for the non-linear phases of galaxy formation are set by the post-recombination power spectrum of density fluctuations. We investigate two models for this power spectrum - the first is a straightforward power law, |δk|2 ∝ kn, and the second is Peeble's analytic approximation to the emergent spectrum in a universe dominated by cold dark matter. The normalisation is chosen such that on some scale, say M ∼ 1012M⊙, the objects that condense out have properties - radius and velocity dispersion - resembling ‘typical’ galaxies. There is some ambiguity in this due to the poorly determined mass-to-light ratio of a typical elliptical galaxy — we look at two normalisations, σ1D ∼ 350kms−1 and σ1D ∼ 140kms−1. The choice determines which of Compton cooling or hydrogen cooling is more important during the galaxy formation period. The non-linear behaviour of the perturbations is treated by the homogeneous sphere approximation.

scholarly journals Connecting the structure of dark matter haloes to the primordial power spectrum

2020 ◽  
Vol 495 (4) ◽  
pp. 4994-5013 ◽  
Author(s):  
Shaun T Brown ◽  
Ian G McCarthy ◽  
Benedikt Diemer ◽  
Andreea S Font ◽  
Sam G Stafford ◽  
...  
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Mass Density ◽  
Large Body ◽  
Density Fluctuations ◽  
Physical Models ◽  
Halo Structure ◽  
Primordial Power Spectrum

ABSTRACT A large body of work based on collisionless cosmological N-body simulations going back over two decades has advanced the idea that collapsed dark matter (DM) haloes have simple and approximately universal forms for their mass density and pseudo-phase-space density (PPSD) distributions. However, a general consensus on the physical origin of these results has not yet been reached. In the present study, we explore to what extent the apparent universality of these forms holds when we vary the initial conditions (i.e. the primordial power spectrum of density fluctuations) away from the standard CMB-normalized case, but still within the context of lambda cold dark matter with a fixed expansion history. Using simulations that vary the initial amplitude and shape, we show that the structure of DM haloes retains a clear memory of the initial conditions. Specifically, increasing (lowering) the amplitude of fluctuations increases (decreases) the concentration of haloes and, if pushed far enough, the density profiles deviate strongly from the NFW form that is a good approximation for the CMB-normalized case. Although, an Einasto form works well. Rather than being universal, the slope of the PPSD (or pseudo-entropy) profile steepens (flattens) with increasing (decreasing) power spectrum amplitude and can exhibit a strong halo mass dependence. Our results therefore indicate that the previously identified universality of the structure of DM haloes is mostly a consequence of adopting a narrow range of (CMB-normalized) initial conditions for the simulations. Our new suite provides a useful test-bench against which physical models for the origin of halo structure can be validated.

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