scholarly journals Cosmology from cosmic shear power spectra with Subaru Hyper Suprime-Cam first-year data

2019 ◽  
Vol 71 (2) ◽  
Author(s):  
Chiaki Hikage ◽  
Masamune Oguri ◽  
Takashi Hamana ◽  
Surhud More ◽  
Rachel Mandelbaum ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Cold Dark Matter ◽  
Signal To Noise Ratio ◽  
Power Spectra ◽  
First Year ◽  
Ratio Test ◽  
Photometric Redshifts ◽  
Spectrum Measurement ◽  
Bayesian Evidence ◽  
Cosmic Shear

Abstract We measure cosmic weak lensing shear power spectra with the Subaru Hyper Suprime-Cam (HSC) survey first-year shear catalog covering 137 deg2 of the sky. Thanks to the high effective galaxy number density of ∼17 arcmin−2, even after conservative cuts such as a magnitude cut of i < 24.5 and photometric redshift cut of 0.3 ≤ z ≤ 1.5, we obtain a high-significance measurement of the cosmic shear power spectra in four tomographic redshift bins, achieving a total signal-to-noise ratio of 16 in the multipole range 300 ≤ ℓ ≤ 1900. We carefully account for various uncertainties in our analysis including the intrinsic alignment of galaxies, scatters and biases in photometric redshifts, residual uncertainties in the shear measurement, and modeling of the matter power spectrum. The accuracy of our power spectrum measurement method as well as our analytic model of the covariance matrix are tested against realistic mock shear catalogs. For a flat Λ cold dark matter model, we find $S\,_{8}\equiv \sigma _8(\Omega _{\rm m}/0.3)^\alpha =0.800^{+0.029}_{-0.028}$ for α = 0.45 ($S\,_8=0.780^{+0.030}_{-0.033}$ for α = 0.5) from our HSC tomographic cosmic shear analysis alone. In comparison with Planck cosmic microwave background constraints, our results prefer slightly lower values of S8, although metrics such as the Bayesian evidence ratio test do not show significant evidence for discordance between these results. We study the effect of possible additional systematic errors that are unaccounted for in our fiducial cosmic shear analysis, and find that they can shift the best-fit values of S8 by up to ∼0.6 σ in both directions. The full HSC survey data will contain several times more area, and will lead to significantly improved cosmological constraints.

scholarly journals The anisotropy of the power spectrum in periodic cosmological simulations

2021 ◽  
Vol 503 (4) ◽  
pp. 5638-5645
Author(s):  
Gábor Rácz ◽  
István Szapudi ◽  
István Csabai ◽  
László Dobos
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Power Spectra ◽  
Cosmological Simulations ◽  
Spherical Collapse ◽  
Lower Amplitude ◽  
Hydrodynamical Simulations

ABSTRACT The classical gravitational force on a torus is anisotropic and always lower than Newton’s 1/r2 law. We demonstrate the effects of periodicity in dark matter only N-body simulations of spherical collapse and standard Lambda cold dark matter (ΛCDM) initial conditions. Periodic boundary conditions cause an overall negative and anisotropic bias in cosmological simulations of cosmic structure formation. The lower amplitude of power spectra of small periodic simulations is a consequence of the missing large-scale modes and the equally important smaller periodic forces. The effect is most significant when the largest mildly non-linear scales are comparable to the linear size of the simulation box, as often is the case for high-resolution hydrodynamical simulations. Spherical collapse morphs into a shape similar to an octahedron. The anisotropic growth distorts the large-scale ΛCDM dark matter structures. We introduce the direction-dependent power spectrum invariant under the octahedral group of the simulation volume and show that the results break spherical symmetry.

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 Angular Momentum Growth around Local Density Maxima

1988 ◽  
Vol 130 ◽  
pp. 552-552
Author(s):  
A. F. Heavens ◽  
J. A. Peacock
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Power Spectrum ◽  
Total Angular Momentum ◽  
Cold Dark Matter ◽  
Local Density ◽  
Probability Distributions ◽  
Power Spectra ◽  
Elliptical Galaxies ◽  
Angular Momenta

We have calculated the growth of angular momentum about local density maxima at early epochs. We find that high peaks experience higher torques than low peaks, counteracting the short collapse time during which the high peaks can acquire angular momentum. Which effect is dominant depends on the perturbation power spectrum: for power spectra characteristic of both cold dark matter and hot dark matter, the effects nearly cancel, and the total angular momentum acquired by a collapsing object is almost independent of the height of the peak. Furthermore, the distributions of angular momenta acquired by collapsing protosystems are extremely broad, for all power spectra, far exceeding any modest differences between peaks of different height.These results indicate that it is not possible to account for the systematic differences in angular momentum properties of disk and elliptical galaxies simply by postulating that the latter arise from fluctuations of greater overdensity, contrary to some recent suggestions. The figure shows the probability distributions for the final angular momentum acquired by peaks of dimensionless height 1–4, for a power spectrum similar to cold dark matter. A fuller account of this work has been submitted to MNRAS.

scholarly journals The lensing properties of subhaloes in massive elliptical galaxies in sterile neutrino cosmologies

2019 ◽  
Vol 491 (1) ◽  
pp. 1295-1310 ◽  
Author(s):  
Giulia Despali ◽  
Mark Lovell ◽  
Simona Vegetti ◽  
Robert A Crain ◽  
Benjamin D Oppenheimer
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Distribution Density ◽  
Sterile Neutrino ◽  
Power Spectra ◽  
Mass Function ◽  
Elliptical Galaxies ◽  
Hydrodynamical Simulations

ABSTRACT We use high-resolution hydrodynamical simulations run with the EAGLE model of galaxy formation to study the differences between the properties of – and subsequently the lensing signal from – subhaloes of massive elliptical galaxies at redshift 0.2, in Cold and Sterile Neutrino (SN) Dark Matter models. We focus on the two 7 keV SN models that bracket the range of matter power spectra compatible with resonantly produced SN as the source of the observed 3.5 keV line. We derive an accurate parametrization for the subhalo mass function in these two SN models relative to cold dark matter (CDM), as well as the subhalo spatial distribution, density profile, and projected number density and the dark matter fraction in subhaloes. We create mock lensing maps from the simulated haloes to study the differences in the lensing signal in the framework of subhalo detection. We find that subhalo convergence is well described by a lognormal distribution and that signal of subhaloes in the power spectrum is lower in SN models with respect to CDM, at a level of 10–80 per cent, depending on the scale. However, the scatter between different projections is large and might make the use of power spectrum studies on the typical scales of current lensing images very difficult. Moreover, in the framework of individual detections through gravitational imaging a sample of ≃30 lenses with an average sensitivity of $M_{\rm {sub}} = 5 \times 10^{7}\, {\rm M}_{\odot}$ would be required to discriminate between CDM and the considered sterile neutrino models.

scholarly journals Cosmic infrared background measurements and star formation history from Planck

2014 ◽  
Vol 10 (S306) ◽  
pp. 144-146
Author(s):  
Paolo Serra ◽  
Keyword(s):  
Star Formation ◽  
Power Spectrum ◽  
Signal To Noise Ratio ◽  
Spectral Energy Distribution ◽  
Power Spectra ◽  
Star Formation History ◽  
Spectral Energy ◽  
Formation History ◽  
Infrared Background ◽  
Cosmic Infrared Background

AbstractWe present new measurements of Cosmic Infrared Background (CIB) anisotropies using Planck. Combining HFI data with IRAS, the angular auto- and cross-frequency power spectrum is measured from 143 to 3000 GHz. After careful removal of the contaminants (cosmic microwave background anisotropies, Galactic dust and Sunyaev-Zeldovich emission), and a complete study of systematics, the CIB power spectrum is measured with unprecedented signal to noise ratio from angular multipoles ℓ ~ 150 to 2500. The interpretation based on the halo model is able to associate star-forming galaxies with dark matter halos and their subhalos, using a parametrized relation between the dust-processed infrared luminosity and (sub-)halo mass, and it allows to simultaneously fit all auto- and cross- power spectra very well. We find that the star formation history is well constrained up to redshifts around 2, and agrees with recent estimates of the obscured star-formation density using Spitzer and Herschel. However, at higher redshift, the accuracy of the star formation history measurement is strongly degraded by the uncertainty in the spectral energy distribution of CIB galaxies. We also find that the mean halo mass which is most efficient at hosting star formation is log(Meff/M⊙) = 12.6 and that CIB galaxies have warmer temperatures as redshift increases.

scholarly journals Power spectrum of halo intrinsic alignments in simulations

2020 ◽  
Vol 501 (1) ◽  
pp. 833-852
Author(s):  
Toshiki Kurita ◽  
Masahiro Takada ◽  
Takahiro Nishimichi ◽  
Ryuichi Takahashi ◽  
Ken Osato ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Cosmological Parameters ◽  
Three Dimensional ◽  
Power Spectra ◽  
Acoustic Oscillations ◽  
Matter Power Spectrum ◽  
Sample Covariance ◽  
Non Linear

ABSTRACT We use a suite of N-body simulations to study intrinsic alignments (IA) of halo shapes with the surrounding large-scale structure in the ΛCDM model. For this purpose, we develop a novel method to measure multipole moments of the three-dimensional power spectrum of the E-mode field of halo shapes with the matter/halo distribution, $P_{\delta E}^{(\ell)}(k)$ (or $P^{(\ell)}_{{\rm h}E}$), and those of the auto-power spectrum of the E-mode, $P^{(\ell)}_{EE}(k)$, based on the E/B-mode decomposition. The IA power spectra have non-vanishing amplitudes over the linear to non-linear scales, and the large-scale amplitudes at k ≲ 0.1 h−1 Mpc are related to the matter power spectrum via a constant coefficient (AIA), similar to the linear bias parameter of galaxy or halo density field. We find that the cross- and auto-power spectra PδE and PEE at non-linear scales, k ≳ 0.1 h−1 Mpc, show different k-dependences relative to the matter power spectrum, suggesting a violation of the non-linear alignment model commonly used to model contaminations of cosmic shear signals. The IA power spectra exhibit baryon acoustic oscillations, and vary with halo samples of different masses, redshifts, and cosmological parameters (Ωm, S8). The cumulative signal-to-noise ratio for the IA power spectra is about 60 per cent of that for the halo density power spectrum, where the super-sample covariance is found to give a significant contribution to the total covariance. Thus our results demonstrate that the IA power spectra of galaxy shapes, measured from imaging and spectroscopic surveys for an overlapping area of the sky, can be used to probe the underlying matter power spectrum, the primordial curvature perturbations, and cosmological parameters, in addition to the standard galaxy density power spectrum.

scholarly journals Bayesian forward modelling of cosmic shear data

2021 ◽  
Vol 502 (2) ◽  
pp. 3035-3044
Author(s):  
Natalia Porqueres ◽  
Alan Heavens ◽  
Daniel Mortlock ◽  
Guilhem Lavaux
Keyword(s):  
Power Spectrum ◽  
Power Spectra ◽  
Density Field ◽  
Matter Distribution ◽  
Bayesian Hierarchical ◽  
Matter Power Spectrum ◽  
Field Samples ◽  
Dark Matter Distribution ◽  
Cosmic Shear ◽  
Non Gaussian

ABSTRACT We present a Bayesian hierarchical modelling approach to infer the cosmic matter density field, and the lensing and the matter power spectra, from cosmic shear data. This method uses a physical model of cosmic structure formation to infer physically plausible cosmic structures, which accounts for the non-Gaussian features of the gravitationally evolved matter distribution and light-cone effects. We test and validate our framework with realistic simulated shear data, demonstrating that the method recovers the unbiased matter distribution and the correct lensing and matter power spectrum. While the cosmology is fixed in this test, and the method employs a prior power spectrum, we demonstrate that the lensing results are sensitive to the true power spectrum when this differs from the prior. In this case, the density field samples are generated with a power spectrum that deviates from the prior, and the method recovers the true lensing power spectrum. The method also recovers the matter power spectrum across the sky, but as currently implemented, it cannot determine the radial power since isotropy is not imposed. In summary, our method provides physically plausible inference of the dark matter distribution from cosmic shear data, allowing us to extract information beyond the two-point statistics and exploiting the full information content of the cosmological fields.

First Year WMAP Observations

2005 ◽  
Vol 216 ◽  
pp. 18-27
Author(s):  
C. L. Bennett
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Large Angle ◽  
Baryon Density ◽  
First Year ◽  
Microwave Background ◽  
Sky Survey ◽  
Temperature Polarization ◽  
Best Fit

The results of the first year WMAP sky survey are full sky microwave maps in five frequency bands from 23 to 94 GHz. Calibration errors are < 0.5% and the low systematic error level is well specified. The cosmic microwave background (CMB) is separated from the foregrounds using the multifrequency data. The 2 ≤ l ≤ 900 anisotropy power spectrum is cosmic variance limited for l < 354 with a signal-to-noise ratio >1 per mode to l = 658. The temperature-polarization cross-power spectrum reveals both acoustic features and a large angle correlation from reionization. The optical depth of reionization is τ = 0.17 ± 0.04. A best-fit cosmological model to the CMB and other measures of large scale structure works remarkably well with only a few parameters. The age of the best-fit universe is t0 = 13.7 ± 0.2 Gyr old. The matter density is Ωmh2 = 0.135+0.008--0.009, the baryon density is Ωbh2 = 0.0224 ± 0.0009, and the total mass-energy of the universe is Ωtot = 1.02±0.02. For WMAP data alone, ns = 0.99 ± 0.04. The lack of CMB fluctuation power on the largest angular scales reported by COBE and confirmed by WMAP is intriguing. WMAP continues to operate, so results will improve.

scholarly journals Exploring the Tension between Current Cosmic Microwave Background and Cosmic Shear Data

Symmetry ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 585 ◽  
Author(s):  
Eleonora Di Valentino ◽  
Sarah Bridle
Keyword(s):  
Dark Matter ◽  
Cosmic Microwave Background ◽  
Cold Dark Matter ◽  
Power Spectra ◽  
Imaging Data ◽  
Microwave Background ◽  
Phenomenological Parameter ◽  
Scaling Parameter ◽  
Massive Neutrinos ◽  
Cosmic Shear

This paper provides a snapshot of the formal S 8 ≡ σ 8 Ω m / 0.3 tension between Planck 2015 and the Kilo Degree Survey of450 deg 2 of imaging data (KiDS-450) or the Canada France Hawaii Lensing Survey (CFHTLenS). We find that the Cosmic Microwave Bckground (CMB) and cosmic shear datasets are in tension in the standard Λ Cold Dark Matter ( Λ CDM) model, and that adding massive neutrinos does not relieve the tension. If we include an additional scaling parameter on the CMB lensing amplitude A l e n s , we find that this can put in agreement the Planck 2015 with the cosmic shear data. A l e n s is a phenomenological parameter that is found to be more than 2 σ higher than the expected value in the Planck 2015 data, suggesting an higher amount of lensing in the power spectra, not supported by the trispectrum analysis.

scholarly journals Cosmological constraints from cosmic shear two-point correlation functions with HSC survey first-year data

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Takashi Hamana ◽  
Masato Shirasaki ◽  
Satoshi Miyazaki ◽  
Chiaki Hikage ◽  
Masamune Oguri ◽  
...  
Keyword(s):  
Gravitational Lensing ◽  
Correlation Functions ◽  
Cold Dark Matter ◽  
First Year ◽  
Model Errors ◽  
Redshift Distribution ◽  
Cosmological Constraints ◽  
Modeling Uncertainties ◽  
Point Correlation ◽  
Cosmic Shear

Abstract We present measurements of cosmic shear two-point correlation functions (TPCFs) from Hyper Suprime-Cam Subaru Strategic Program (HSC) first-year data, and derive cosmological constraints based on a blind analysis. The HSC first-year shape catalog is divided into four tomographic redshift bins ranging from $z=0.3$ to 1.5 with equal widths of $\Delta z =0.3$. The unweighted galaxy number densities in each tomographic bin are 5.9, 5.9, 4.3, and $2.4\:$arcmin$^{-2}$ from the lowest to highest redshifts, respectively. We adopt the standard TPCF estimators, $\xi _\pm$, for our cosmological analysis, given that we find no evidence of significant B-mode shear. The TPCFs are detected at high significance for all 10 combinations of auto- and cross-tomographic bins over a wide angular range, yielding a total signal-to-noise ratio of 19 in the angular ranges adopted in the cosmological analysis, $7^{\prime }&lt;\theta &lt;56^{\prime }$ for $\xi _+$ and $28^{\prime }&lt;\theta &lt;178^{\prime }$ for $\xi _-$. We perform the standard Bayesian likelihood analysis for cosmological inference from the measured cosmic shear TPCFs, including contributions from intrinsic alignment of galaxies as well as systematic effects from PSF model errors, shear calibration uncertainty, and source redshift distribution errors. We adopt a covariance matrix derived from realistic mock catalogs constructed from full-sky gravitational lensing simulations that fully account for survey geometry and measurement noise. For a flat $\Lambda$ cold dark matter model, we find $S\,_8 \equiv \sigma _8\sqrt{\Omega _{\rm m}/0.3}=0.804_{-0.029}^{+0.032}$, and $\Omega _{\rm m}=0.346_{-0.100}^{+0.052}$. We carefully check the robustness of the cosmological results against astrophysical modeling uncertainties and systematic uncertainties in measurements, and find that none of them has a significant impact on the cosmological constraints.

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