scholarly journals Semi-analytical study on the generic degeneracy for galaxy clustering measurements

2014 ◽  
Vol 10 (S306) ◽  
pp. 347-350
Author(s):  
Alejandro Guarnizo ◽  
Luca Amendola ◽  
Martin Kunz ◽  
Adrian Vollmer
Keyword(s):  
Growth Rate ◽  
Power Spectrum ◽  
Negative Correlation ◽  
Analytical Study ◽  
Growth Function ◽  
Matrix Formalism ◽  
Galaxy Clustering ◽  
Galaxy Surveys ◽  
The Galaxy ◽  
Better Than

AbstractFrom the galaxy power spectrum in redshift space, we derive semi-analytical results on the generic degeneracy of galaxy clustering measurements. Defining the observables A = Gbσ8 and R = Gfσ8, (being G the growth function, b the bias, f the growth rate, and σ8 the amplitude of the power spectrum), we perform a Fisher matrix formalism to forecast the expected precision of these quantities for a Euclid-like survey. Among the results we found that galaxy surveys have generically a slightly negative correlation between A and R, and they can always measure R about 3.7 to 4.7 times better than A.

scholarly journals Constraining the growth rate of structure with phase correlations

2020 ◽  
Vol 497 (2) ◽  
pp. 1765-1790
Author(s):  
Joyce Byun ◽  
Felipe Oliveira Franco ◽  
Cullan Howlett ◽  
Camille Bonvin ◽  
Danail Obreschkow
Keyword(s):  
Growth Rate ◽  
Correlation Function ◽  
Power Spectrum ◽  
Large Scale ◽  
Large Scale Structure ◽  
Density Field ◽  
Galaxy Surveys ◽  
Additional Information ◽  
Forecasting Method ◽  
The Galaxy

ABSTRACT We show that correlations between the phases of the galaxy density field in redshift space provide additional information about the growth rate of large-scale structure that is complementary to the power-spectrum multipoles. In particular, we consider the multipoles of the line correlation function (LCF), which correlates phases between three collinear points, and use the Fisher forecasting method to show that the LCF multipoles can break the degeneracy between the measurement of the growth rate of structure f and the amplitude of perturbations σ8 that is present in the power-spectrum multipoles at large scales. This leads to an improvement in the measurement of f and σ8 by up to 220 per cent for $k_{\rm max} = 0.15 \, h\, \mathrm{Mpc}^{-1}$ and up to 50 per cent for $k_{\rm max} = 0.30 \, h\, \mathrm{Mpc}^{-1}$ at redshift z = 0.25, with respect to power-spectrum measurements alone for the upcoming generation of galaxy surveys like DESI and Euclid. The average improvements in the constraints on f and σ8 for $k_{\rm max} = 0.15 \, h\, \mathrm{Mpc}^{-1}$ are ∼90 per cent for the DESI BGS sample with mean redshift $\overline{z}=0.25$, ∼40 per cent for the DESI ELG sample with $\overline{z}=1.25$, and ∼40 per cent for the Euclid Hα galaxies with $\overline{z}=1.3$. For $k_{\rm max} = 0.30 \, h\, \mathrm{Mpc}^{-1}$, the average improvements are ∼40 per cent for the DESI BGS sample and ∼20 per cent for both the DESI ELG and Euclid Hα galaxies.

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 Minimum variance estimation of galaxy power spectrum in redshift space

2020 ◽  
Vol 498 (1) ◽  
pp. L77-L81
Author(s):  
Maresuke Shiraishi ◽  
Teppei Okumura ◽  
Naonori S Sugiyama ◽  
Kazuyuki Akitsu
Keyword(s):  
Power Spectrum ◽  
Variance Estimation ◽  
Signal To Noise Ratio ◽  
Minimum Variance ◽  
Wide Angle ◽  
Decomposition Approach ◽  
Galaxy Surveys ◽  
Angle Data ◽  
The Galaxy ◽  
Decomposition Coefficient

ABSTRACT We study an efficient way to enhance the measurability of the galaxy density and/or velocity power spectrum in redshift space. It is based on the angular decomposition with the tripolar spherical harmonic (TripoSH) basis and applicable even to galaxy distributions in wide-angle galaxy surveys. While non-trivial multipole-mode mixings are inevitable in the covariance of the Legendre decomposition coefficient commonly used in the small-angle power spectrum analysis, our analytical computation of the covariance of the TripoSH decomposition coefficient shows that such mixings are absent by virtue of high separability of the TripoSH basis, yielding the minimum variance. Via the simple signal-to-noise ratio assessment, we confirm that the detectability improvement by the TripoSH decomposition approach becomes more significant at higher multipole modes, and the hexadecapole of the density power spectrum has two orders of magnitude improvement. The TripoSH decomposition approach is expected to be applied to not only currently available survey data but also forthcoming wide-angle data, and to bring about something new or much more accurate cosmological information.

scholarly journals Reducing the variance of redshift space distortion measurements from mock galaxy catalogues with different lines of sight

2020 ◽  
Vol 500 (1) ◽  
pp. 259-271
Author(s):  
Alex Smith ◽  
Arnaud de Mattia ◽  
Etienne Burtin ◽  
Chia-Hsun Chuang ◽  
Cheng Zhao
Keyword(s):  
Power Spectrum ◽  
Cross Correlation ◽  
Cosmological Parameters ◽  
Galaxy Surveys ◽  
Cpu Time ◽  
Cent Level ◽  
Space Distortion ◽  
The Impact ◽  
Line Galaxy ◽  
Better Than

ABSTRACT Accurate mock catalogues are essential for assessing systematics in the cosmological analysis of large galaxy surveys. Anisotropic two-point clustering measurements from the same simulation show some scatter for different lines of sight (LOS), but are on average equal, due to cosmic variance. This results in scatter in the measured cosmological parameters. We use the OuterRim N-body simulation halo catalogue to investigate this, considering the three simulation axes as LOS. The quadrupole of the two-point statistics is particularly sensitive to changes in the LOS, with subper cent level differences in the velocity distributions resulting in ∼1.5 σ shifts on large scales. Averaging over multiple LOS can reduce the impact of cosmic variance. We derive an expression for the Gaussian cross-correlation between the power spectrum multipole measurements, for any two LOS, including shot noise, and the corresponding reduction in variance in the average measurement. Quadrupole measurements are anticorrelated, and for three orthogonal LOS, the variance on the average measurement is reduced by more than 1/3. We perform a Fisher analysis to predict the corresponding gain in precision on the cosmological parameter measurements, which we compare against a set of 300 extended Baryon Oscillation Spectroscopic Survey emission-line galaxy EZmocks. The gain in fσ8, which measures the growth of structure, is also better than 1/3. Averaging over multiple LOS in future mock challenges will allow the redshift space distortion models to be constrained with the same systematic error, with less than three times the CPU time.

scholarly journals Assessing non-linear models for galaxy clustering – II. Model validation and forecasts for Stage IV surveys

2020 ◽  
Vol 493 (4) ◽  
pp. 5301-5322 ◽  
Author(s):  
Benjamin Bose ◽  
Alkistis Pourtsidou ◽  
Katarina Markovič ◽  
Florian Beutler
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Linear Models ◽  
Stage Iv ◽  
Multipole Expansion ◽  
Effective Field ◽  
Nuisance Parameters ◽  
Galaxy Clustering ◽  
Galaxy Surveys ◽  
Non Linear

ABSTRACT Accurate modelling of non-linear scales in galaxy clustering will be crucial for data analysis of Stage IV galaxy surveys. A selection of competing non-linear models must be made based on validation studies. We provide a comprehensive set of forecasts of two different models for the halo redshift space power spectrum, namely the commonly applied TNS model and an effective field theory of large-scale structure (EFTofLSS) inspired model. Using simulation data and a least-χ2 analysis, we determine ranges of validity for the models. We then conduct an exploratory Fisher analysis using the full anisotropic power spectrum to investigate parameter degeneracies. We proceed to perform an MCMC analysis utilizing the monopole, quadrupole, and hexadecapole spectra, with a restricted range of scales for the latter in order to avoid biasing our growth rate, f, constraint. We find that the TNS model with a Lorentzian damping and standard Eulerian perturbative modelling outperforms other variants of the TNS model. Our MCMC analysis finds that the EFTofLSS-based model may provide tighter marginalized constraints on f at z = 0.5 and z = 1 than the TNS model, despite having additional nuisance parameters. However this depends on the range of scales used as well as the fiducial values and priors on the EFT nuisance parameters. Finally, we extend previous work to provide a consistent comparison between the Fisher matrix and MCMC forecasts using the multipole expansion formalism, and find good agreement between them.

scholarly journals Testing gravity with galaxy-galaxy lensing and redshift-space distortions using CFHT-Stripe 82, CFHTLenS, and BOSS CMASS datasets

2019 ◽  
Vol 627 ◽  
pp. A137 ◽  
Author(s):  
E. Jullo ◽  
S. de la Torre ◽  
M.-C. Cousinou ◽  
S. Escoffier ◽  
C. Giocoli ◽  
...  
Keyword(s):  
Growth Rate ◽  
General Relativity ◽  
Power Spectrum ◽  
Spectroscopic Data ◽  
Systematic Errors ◽  
Structure Parameter ◽  
Photometric Redshifts ◽  
Galaxy Clustering ◽  
Non Linear ◽  
Space Distortion

The combination of galaxy-galaxy lensing (GGL) and redshift space distortion of galaxy clustering (RSD) is a privileged technique to test general relativity predictions and break degeneracies between the growth rate of structure parameter f and the amplitude of the linear power spectrum σ8. We performed a joint GGL and RSD analysis on 250 sq. deg using shape catalogues from CFHTLenS and CFHT-Stripe 82 and spectroscopic redshifts from the BOSS CMASS sample. We adjusted a model that includes non-linear biasing, RSD, and Alcock–Paczynski effects. We used an N-body simulation supplemented by an abundance matching prescription for CMASS galaxies to build a set of overlapping lensing and clustering mocks. Together with additional spectroscopic data, this helps us to quantify and correct several systematic errors, such as photometric redshifts. We find f(z = 0.57) = 0.95 ± 0.23, σ8(z = 0.57) = 0.55 ± 0.07 and Ωm = 0.31 ± 0.08, in agreement with Planck cosmological results 2018. We also estimate the probe of gravity EG = 0.43 ± 0.10, in agreement with ΛCDM−GR predictions of EG = 0.40. This analysis reveals that RSD efficiently decreases the GGL uncertainty on Ωm by a factor of 4 and by 30% on σ8. We make our mock catalogues available on the Skies and Universe database.

scholarly journals Neutrino masses from CMB B-mode polarization and cosmic growth rate

2015 ◽  
Vol 30 (01) ◽  
pp. 1550001 ◽  
Author(s):  
Koichi Hirano
Keyword(s):  
Growth Rate ◽  
Monte Carlo ◽  
Power Spectrum ◽  
Neutrino Masses ◽  
Mcmc Method ◽  
Microwave Background ◽  
The Galaxy ◽  
Redshift Survey ◽  
Galaxy Bias ◽  
Planck Satellite

Constraints on neutrino masses are estimated based on future observations of the cosmic microwave background (CMB), which includes the B-mode polarization produced by CMB lensing from the Planck satellite, and the growth rate of cosmic structure from the Euclid redshift survey by using the Markov–Chain Monte-Carlo (MCMC) method. The error in the bound on the total neutrino mass is estimated to be Δ ∑ mν = 0.075 eV with a 68% confidence level. By using the growth rate rather than the galaxy power spectrum, accurate constraints are obtained, since the growth rate is less influenced by the uncertainty regarding galaxy bias than by the galaxy power spectrum.

scholarly journals Redshift inference from the combination of galaxy colours and clustering in a hierarchical Bayesian model – Application to realistic N-body simulations

2020 ◽  
Vol 498 (2) ◽  
pp. 2614-2631 ◽  
Author(s):  
Alex Alarcon ◽  
Carles Sánchez ◽  
Gary M Bernstein ◽  
Enrique Gaztañaga
Keyword(s):  
Bayesian Model ◽  
Prior Information ◽  
Broad Band ◽  
Real Data ◽  
Hierarchical Bayesian ◽  
Hierarchical Bayesian Model ◽  
Galaxy Clustering ◽  
Galaxy Surveys ◽  
Systematic Uncertainties ◽  
The Galaxy

ABSTRACT Photometric galaxy surveys constitute a powerful cosmological probe but rely on the accurate characterization of their redshift distributions using only broad-band imaging, and can be very sensitive to incomplete or biased priors used for redshift calibration. A hierarchical Bayesian model has recently been developed to estimate those from the robust combination of prior information, photometry of single galaxies, and the information contained in the galaxy clustering against a well-characterized tracer population. In this work, we extend the method so that it can be applied to real data, developing some necessary new extensions to it, especially in the treatment of galaxy clustering information, and we test it on realistic simulations. After marginalizing over the mapping between the clustering estimator and the actual density distribution of the sample galaxies, and using prior information from a small patch of the survey, we find the incorporation of clustering information with photo-z’s tightens the redshift posteriors and overcomes biases in the prior that mimic those happening in spectroscopic samples. The method presented here uses all the information at hand to reduce prior biases and incompleteness. Even in cases where we artificially bias the spectroscopic sample to induce a shift in mean redshift of $\Delta \bar{z} \approx 0.05,$ the final biases in the posterior are $\Delta \bar{z} \lesssim 0.003.$ This robustness to flaws in the redshift prior or training samples would constitute a milestone for the control of redshift systematic uncertainties in future weak lensing analyses.

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