Growth Rate Of Cosmic Structure Research Articles

Constraining the growth rate on linear scales by combining SKAO and DESI surveys

In the pursuit of understanding the large-scale structure of the Universe, the synergy between complementary cosmological surveys has proven to be a powerful tool. Using multiple tracers of the large-scale structure can significantly improve the constraints on cosmological parameters. We explore the potential of combining the Square Kilometre Array Observatory (SKAO) and the Dark Energy Spectroscopic Instrument (DESI) spectroscopic surveys to enhance precision on the growth rate of cosmic structures. We employ a multi-tracer Fisher analysis to estimate precision on the growth rate when using pairs of mock surveys that are based on SKAO and DESI specifications. The pairs are at both low and high redshifts. For SKA-MID, we use the HI galaxy and the HI intensity mapping samples. In order to avoid the complexities and uncertainties at small scales, we confine the analysis to scales where linear perturbations are reliable. The consequent loss of signal in each individual survey is mitigated by the gains from the multi-tracer. After marginalising over cosmological and nuisance parameters, we find a significant improvement in the precision on the growth rate.

On the correlations of galaxy peculiar velocities and their covariance

ABSTRACT Measurements of the peculiar velocities of large samples of galaxies enable new tests of the standard cosmological model, including determination of the growth rate of cosmic structure that encodes gravitational physics. With the size of such samples now approaching hundreds of thousands of galaxies, complex statistical analysis techniques and models are required to extract cosmological information. In this paper, we summarize how correlation functions between galaxy velocities, and with the surrounding large-scale structure, may be utilized to test cosmological models. We present new determinations of the analytical covariance between such correlation functions, which may be useful for cosmological likelihood analyses. The statistical model we use to determine these covariances includes the sample selection functions, observational noise, curved-sky effects, and redshift-space distortions. By comparing these covariance determinations with corresponding estimates from large suites of cosmological simulations, we demonstrate that these analytical models recover the key features of the covariance between different statistics and separations, and produce similar measurements of the growth rate of structure.

The completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: measurement of the growth rate of structure from the small-scale clustering of the luminous red galaxy sample

ABSTRACT We measure the small-scale clustering of the Data Release 16 extended Baryon Oscillation Spectroscopic Survey Luminous Red Galaxy sample, corrected for fibre-collisions using Pairwise Inverse Probability weights, which give unbiased clustering measurements on all scales. We fit to the monopole and quadrupole moments and to the projected correlation function over the separation range $7-60\, h^{-1}{\rm Mpc}$ with a model based on the aemulus cosmological emulator to measure the growth rate of cosmic structure, parametrized by fσ8. We obtain a measurement of fσ8(z = 0.737) = 0.408 ± 0.038, which is 1.4σ lower than the value expected from 2018 Planck data for a flat ΛCDM model, and is more consistent with recent weak-lensing measurements. The level of precision achieved is 1.7 times better than more standard measurements made using only the large-scale modes of the same sample. We also fit to the data using the full range of scales $0.1\text{--}60\, h^{-1}{\rm Mpc}$ modelled by the aemulus cosmological emulator and find a 4.5σ tension in the amplitude of the halo velocity field with the Planck + ΛCDM model, driven by a mismatch on the non-linear scales. This may not be cosmological in origin, and could be due to a breakdown in the Halo Occupation Distribution model used in the emulator. Finally, we perform a robust analysis of possible sources of systematics, including the effects of redshift uncertainty and incompleteness due to target selection that were not included in previous analyses fitting to clustering measurements on small scales.

Observational constraints on Starobinsky f(R) cosmology from cosmic expansion and structure growth data

The unknown physical nature of the Dark Energy motivates in cosmology the study of modifications of the gravity theory at large distances. One of these types of modifications is to consider gravity theories, generally termed as f(R). In this paper we use observational data to both constrain and test the Starobinsky f(R) model (Starobinsky in JETP Lett 86(3):157–163, 2007), using updated measurements from the dynamics of the expansion of the universe, H(z); and the growth rate of cosmic structures, [fsigma _8](z), where the distinction between the concordance varLambda CDM model and modified gravity models f(R) becomes clearer. We use MCMC likelihood analyses to explore the parameters space of the f(R) model using H(z) and [fsigma _8](z) data, both individually and jointly, and further, examine which of the models best fits the joint data. To further test the Starobinsky model, we use a method proposed by Linder (Astropart Phys 86:41–45, 2017), where the data from the observables is jointly binned in redshift space. This allows one to further explore the model’s parameter that better fits the data in comparison to the varLambda CDM model. The joint analysis of H(z) and [fsigma _8](z) show that the n=2–Starobinsky f(R) model fits well the observational data. In the end, we confirm that this joint analysis is able to break the degenerescence between modified gravity models as proposed in the original work (Starobinsky 2007). Our results indicate that the f(R) Starobinsky model provides a good fit to the currently available data for a set of values of its parameters, being, therefore, a possible alternative to the varLambda CDM model.

The homogeneity scale and the growth rate of cosmic structures

ABSTRACT We propose a novel approach to obtain the growth rate of cosmic structures, f(z), from the evolution of the cosmic homogeneity scale, RH(z). Our methodology needs two ingredients in a specific functional form: RH(z) data and the matter two-point correlation function today, i.e. ξ(r, z = 0). We use a Gaussian Process approach to reconstruct the function RH. In the absence of suitable observational information of the matter correlation function in the local Universe, z ≃ 0, we assume a fiducial cosmology to obtain ξ(r, z = 0). For this reason, our final result turns out to be a consistency test of the cosmological model assumed. Our results show a good agreement between: (i) the growth rate $f^{R_{\text{H}}}(z)$ obtained through our approach, (ii) the fΛCDM(z) expected in the fiducial model, and (iii) the best-fitting f(z) from data compiled in the literature. Moreover, using this data compilation, we perform a Gaussian Process to reconstruct the growth rate function fdata(z) and compare it with the function $f^{R_{\text{H}}}(z)$ finding a concordance of $\lt \!2 \, \sigma$, a good result considering the few data available for both reconstruction processes. With more accurate RH(z) data, from forthcoming surveys, the homogeneity scale function might be better determined and would have the potential to discriminate between ΛCDM and alternative scenarios as a new cosmological observable.

C3 Cluster Clustering Cosmology I. New Constraints on the Cosmic Growth Rate at z ∼ 0.3 from Redshift-space Clustering Anisotropies

Abstract Redshift-space distortions in the clustering of galaxy clusters provide a novel probe to test the theory of gravity on cosmological scales. The aim of this work is to derive new constraints on the linear growth rate of cosmic structures from the redshift-space two-point correlation function of galaxy clusters. We construct a large spectroscopic catalog of optically selected clusters from the Sloan Digital Sky Survey. The selected sample consists of 43,743 clusters in the redshift range 0.1 < z < 0.42, with masses estimated from weak-lensing calibrated scaling relations. We measure the transverse and radial wedges of the two-point correlation function of the selected clusters. Modeling the redshift-space clustering anisotropies, we provide the first constraints on the linear growth rate from cluster clustering. The cluster masses are used to set a prior on the linear bias of the sample. This represents the main advantage in using galaxy clusters as cosmic probes, instead of galaxies. Assuming a standard cosmological model consistent with the latest cosmic microwave background constraints, we do not find any evidence of deviations from general relativity. Specifically, we get the value of the growth rate times the matter power spectrum normalization parameter fσ 8 = 0.44 ± 0.05, at an effective redshift of z = 0.275.

The growth rate of cosmic structures in the local Universe with the ALFALFA survey

ABSTRACT We investigate the growth rate of structures in the local Universe. For this, we use as a cosmological tracer the HI line extra-galactic sources from the Arecibo Legacy Fast ALFA (ALFALFA) survey to obtain a measurement of the normalized growth rate parameter, fσ8, considered a powerful tool to constrain alternative models of gravity. For these analyses, we calculate the Local Group velocity due to the matter structures distribution in the ALFALFA catalogue and compare it with the Local Group velocity relative to the Cosmic Microwave Background frame to obtain the velocity scale parameter, β. Using Monte Carlo realizations and lognormal simulations, our methodology quantifies the errors introduced by shot-noise and partial sky coverage of the analysed data. The measurement of the velocity scale parameter β and the calculation of the matter fluctuation of the cosmological tracer, $\sigma _{8}^{\text{tr}}$, lead us to fσ8 = 0.46 ± 0.06 at $\bar{z} = 0.013$, in good agreement (at 1σ level) with the value expected in the ΛCDM concordance model. In addition, our analyses of the ALFALFA sample also provide a measurement of the growth rate of structures $f = 0.56 \pm 0.07$, at $\bar{z} = 0.013$.

Testing late-time cosmic acceleration with uncorrelated baryon acoustic oscillation dataset

Baryon acoustic oscillations (BAO) involve measuring the spatial distribution of galaxies to determine the growth rate of cosmic structures. We derive constraints on cosmological parameters from 17 uncorrelated BAO measurements that were collected from 333 published data points in the effective redshift range 0.106 ≤ z ≤ 2.36. We test the correlation of the subset using a random covariance matrix. The Λ cold dark matter (ΛCDM) model fit yields the cosmological parameters Ωm = 0.261 ± 0.028 and ΩΛ = 0.733 ± 0.021. Combining the BAO data with the Cosmic Chronometers data, the Pantheon type Ia supernova, and the Hubble diagram of gamma-ray bursts and quasars, the Hubble constant yields 69.85 ± 1.27 km s−1Mpc−1and the sound horizon distance gives 146.1 ± 2.15 Mpc. Beyond the ΛCDM model we test ΩkCDM andwCDM. The spatial curvature is Ωk = −0.076 ± 0.012 and the dark energy equation of states isw = −0.989 ± 0.049. We perform the Akaike information criteria test to compare the three models, and see that ΛCDM scores best.

Joint analysis of 6dFGS and SDSS peculiar velocities for the growth rate of cosmic structure and tests of gravity

ABSTRACT Measurement of peculiar velocities by combining redshifts and distance indicators is a powerful way to measure the growth rate of a cosmic structure and test theories of gravity at low redshift. Here we constrain the growth rate of the structure by comparing observed Fundamental Plane peculiar velocities for 15 894 galaxies from the 6dF Galaxy Survey (6dFGS) and Sloan Digital Sky Survey (SDSS) with predicted velocities and densities from the 2M++ redshift survey. We measure the velocity scale parameter $\beta \equiv {\Omega _{\rm m}^\gamma }/b = 0.372^{+0.034}_{-0.050}$ and $0.314^{+0.031}_{-0.047}$ for 6dFGS and SDSS, respectively, where Ωm is the mass density parameter, γ is the growth index, and b is the bias parameter normalized to the characteristic luminosity of galaxies, L*. Combining 6dFGS and SDSS, we obtain β = 0.341 ± 0.024, implying that the amplitude of the product of the growth rate and the mass fluctuation amplitude is fσ8 = 0.338 ± 0.027 at an effective redshift z = 0.035. Adopting Ωm = 0.315 ± 0.007, as favoured by Planck and using γ = 6/11 for General Relativity and γ = 11/16 for DGP gravity, we get $S_8(z=0) = \sigma _8 \sqrt{\Omega _{\rm m}/0.3} =0.637 \pm 0.054$ and 0.741 ± 0.062 for GR and DGP, respectively. This measurement agrees with other low-redshift probes of large-scale structure but deviates by more than 3σ from the latest Planck CMB measurement. Our results favour values of the growth index γ > 6/11 or a Hubble constant H0 > 70 km s−1 Mpc−1 or a fluctuation amplitude σ8 < 0.8 or some combination of these. Imminent redshift surveys such as Taipan, DESI, WALLABY, and SKA1-MID will help to resolve this tension by measuring the growth rate of cosmic structure to 1 per cent in the redshift range 0 < z < 1.

Complementarity of peculiar velocity surveys and redshift space distortions for testing gravity

Peculiar-velocity surveys of the low-redshift universe have significant leverage to constrain the growth rate of cosmic structure and test gravity. Wide-field imaging surveys combined with multi-object spectrographs (e.g. ZTF2, LSST, DESI, 4MOST) can use Type Ia supernovae as informative tracers of the velocity field, reaching few percent constraints on the growth rate $f\sigma_8$ at $z\lesssim0.2$ where density tracers cannot do better than $\sim10\%$. Combining the high-redshift DESI survey mapping redshift space distortions with a low-redshift supernova peculiar velocity survey using LSST and DESI can determine the gravitational growth index to $\sigma(\gamma)\approx0.02$, testing general relativity. We study the characteristics needed for the peculiar velocity survey, and how its complementarity with clustering surveys improves when going from a $\Lambda$CDM model assumption to a $w_0$-$w_a$ cosmology.

New constraints on the linear growth rate using cosmic voids in the SDSS DR12 datasets

We present a new analysis of the inferred growth rate of cosmic structure measured around voids, using the LOWZ and the CMASS samples in the twelfth data release (DR12) of SDSS. Using a simple multipole analysis we recover a value consistent with $\Lambda$CDM for the inferred linear growth rate normalized by the linear bias: the $\beta$ parameter. This is true in both the mock catalogues and the data, where we find $\beta=0.33\pm0.06$ for the LOWZ sample and $\beta=0.36\pm0.05$ for the CMASS sample. This work demonstrates that we can expect redshift-space distortions around voids to provide unbiased and accurate constraints on the growth rate, complementary to galaxy clustering, using simple linear modelling.

Dark Energy Survey Year 1 Results: Tomographic cross-correlations between Dark Energy Survey galaxies and CMB lensing from South Pole Telescope+Planck

We measure the cross-correlation between redMaGiC galaxies selected from the Dark Energy Survey (DES) year 1 data and gravitational lensing of the cosmic microwave background (CMB) reconstructed from South Pole Telescope (SPT) and Planck data over 1289 deg2. When combining measurements across multiple galaxy redshift bins spanning the redshift range of 0.15<z<0.90, we reject the hypothesis of no correlation at 19.9σ significance. When removing small-scale data points where thermal Sunyaev-Zel’dovich signal and nonlinear galaxy bias could potentially bias our results, the detection significance is reduced to 9.9σ. We perform a joint analysis of galaxy-CMB lensing cross-correlations and galaxy clustering to constrain cosmology, finding Ωm=0.276−0.030+0.029 and S8=σ8Ωm/0.3=0.800−0.094+0.090. We also perform two alternate analyses aimed at constraining only the growth rate of cosmic structure as a function of redshift, finding consistency with predictions from the concordance ΛCDM model. The measurements presented here are part of a joint cosmological analysis that combines galaxy clustering, galaxy lensing and CMB lensing using data from DES, SPT and Planck.Received 2 November 2018DOI:https://doi.org/10.1103/PhysRevD.100.043501© 2019 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCosmic microwave backgroundCosmological parametersLarge scale structure of the UniverseGravitation, Cosmology & Astrophysics

The effects of galaxy assembly bias on the inference of growth rate from redshift-space distortions

The large-scale redshift-space distortion (RSD) in galaxy clustering can probe $f\sigma_8$, a combination of the cosmic structure growth rate and the matter fluctuation amplitude, which can constrain dark energy models and test theories of gravity. While the RSD on small scales (e.g. a few to tens of $h^{-1}{\rm Mpc}$) can further tighten the $f\sigma_8$ constraints, galaxy assembly bias, if not correctly modelled, may introduce systematic uncertainties. Using a mock galaxy catalogue with built-in assembly bias, we perform a preliminary study on how assembly bias may affect the $f\sigma_8$ inference. We find good agreement on scales down to 8--9$h^{-1}{\rm Mpc}$ between a $f\sigma_8$ metric from the redshift-space two-point correlation function with the central-only mock catalogue and that with the shuffled catalogue free of assembly bias, implying that $f\sigma_8$ information can be extracted on such scales even with assembly bias. We then apply the halo occupation distribution (HOD) and three subhalo clustering and abundance matching (SCAM) models to model the redshift-space clustering with the mock. Only the SCAM model based on $V_{\rm peak}$ (used to create the mock) can reproduce the $f\sigma_8$ metric, and the other three could not. However, the $f\sigma_8$ metrics determined from central galaxies from all the models are able to match the expected one down to 8$h^{-1}{\rm Mpc}$. Our results suggest that halo models with no or incorrect assembly bias prescription could still be used to model the RSD down to scales of $\sim 8 h^{-1}{\rm Mpc}$ to tighten the $f\sigma_8$ constraint, with a sample of central galaxies or with a flexible satellite occupation prescription.

Modeling the environmental dependence of the growth rate of cosmic structure

The growth rate of cosmic structure is a powerful cosmological probe for extracting information on the gravitational interactions and dark energy. In the late time Universe, the growth rate becomes non-linear and is usually probed by measuring the two point statistics of galaxy clustering in redshift space up to a limited scale, retaining the constraint on the linear growth rate f. In this letter, we present an alternative method to analyse the growth of structure in terms of local densities, i.e. f(Delta). Using N-body simulations, we measure the function of f(Delta) and show that structure grows faster in high density regions and slower in low density regions. We demonstrate that f(Delta) can be modelled using a log-normal Monte Carlo Random Walk approach, which provides a means to extract cosmological information from f(Delta). We discuss prospects for applying this approach to galaxy surveys.

The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample: anisotropic clustering analysis in configuration space

We explore the cosmological implications of anisotropic clustering measurements of the quasar sample from Data Release 14 of the Sloan Digital Sky Survey IV Extended Baryon Oscillation Spectroscopic Survey (eBOSS) in configuration space. The $\sim 147,000$ quasar sample observed by eBOSS offers a direct tracer of the density field and bridges the gap of previous BAO measurements between redshift $0.8<z<2.2$. By analysing the two-point correlation function characterized by clustering wedges $\xi_{\rm w_i}(s)$ and multipoles $\xi_{\ell}(s)$, we measure the angular diameter distance, Hubble parameter and cosmic structure growth rate. We define a systematic error budget for our measurements based on the analysis of $N$-body simulations and mock catalogues. Based on the DR14 large scale structure quasar sample at the effective redshift $z_{\rm eff}=1.52$, we find the growth rate of cosmic structure $f\sigma_8(z_{\rm eff})=0.396\pm 0.079$, and the geometric parameters $D_{\rm V}(z)/r_{\rm d}=26.47\pm 1.23$, and $F_{\rm AP}(z)=2.53\pm 0.22$, where the uncertainties include both statistical and systematic errors. These values are in excellent agreement with the best-fitting standard ${\rm \Lambda CDM}$ model to the latest cosmic microwave background data from Planck.

Proposal for a Real-Time Detection of our Acceleration through Space.

Our proper acceleration with respect to the cosmic microwave background results in a real-time change of the angular position of distant extragalactic sources. The cosmological component of this aberration drift signal, the noninertial motion generated by the large-scale distribution of matter, can, in principle, be detected by future high-precision astrometric experiments. It will provide interesting consistency tests of the standard model of cosmology, set independent constraints on the amplitude of the Hubble constant and the linear growth rate of cosmic structures, and be instrumental in searching for evidence of new physics beyond the standard model. We present the formalism of this novel cosmological test, discuss the physics to which it is sensitive, and show simulated forecasts of the accuracy with which it can be implemented.

ISW-galaxy cross-correlation in K-mouflage

Cross-correlations between the cosmic microwave background and the galaxy distribution can probe the linear growth rate of cosmic structures, thus providing a powerful tool to investigate different Dark Energy and Modified Gravity models. We explore the possibility of using this observable to probe a particular class of Modified Gravity models, called K-mouflage.

Improved model of redshift-space distortions around voids: Application to quintessence dark energy

Using cosmic voids to probe the growth rate of cosmic structure, and hence the nature of dark energy, is particularly interesting in the context of modified gravity theories that rely on the screening mechanism. In this work we improve the modelling of redshift-space distortions around voids in the dark matter density field, and thus reduce systematic errors in the derivation of cosmological parameters. We also show how specific types of voids can be used to better probe the growth rate, using a flexible void finder. We apply our results to test for a quintessence type of dark energy vs. a LCDM model, and find a good agreement with the fiducial cosmology after implementing an analytical correction to the radial velocity profiles around voids. We additionally outline characteristic imprints of dark energy in the dark matter velocity distributions around voids.

Beyond the growth rate of cosmic structure: Testing modified gravity models with an extra degree of freedom

In ``modified'' gravity the observed acceleration of the universe is explained by changing the gravitational force law or the number of degrees of freedom in the gravitational sector. Both possibilities can be tested by measurements of cosmological structure formation. In this paper we elaborate the details of such tests using the Galileon model as a case study. We pay attention to the possibility that each new degree of freedom may have stochastically independent initial conditions, generating different types of potential well in the early universe and breaking complete correlation between density and velocity power spectra. This ``stochastic bias'' can confuse schemes to parametrize the predictions of modified gravity models, such as the use of the growth parameter $f$ alone. Using data from the WiggleZ Dark Energy Survey we show that it will be possible to obtain constraints using information about the cosmological-scale force law embedded in the multipole power spectra of redshift-space distortions. As an example, we obtain an upper limit on the strength of the conformal coupling to matter in the cubic Galileon model, giving $|1/M|\ensuremath{\lesssim}200/{M}_{\mathrm{P}}$. This allows the fifth-force to be stronger than gravity, but is consistent with zero coupling.

Cosmological constraints from a joint analysis of cosmic growth and expansion

Abstract Combining measurements on the expansion history of the Universe and on the growth rate of cosmic structures is key to discriminate between alternative cosmological frameworks and to test gravity. Recently, Linder proposed a new diagram to investigate the joint evolutionary track of these two quantities. In this letter, we collect the most recent cosmic growth and expansion rate data sets to provide the state-of-the-art observational constraints on this diagram. By performing a joint statistical analysis of both probes, we test the standard Λcold dark matter model, confirming a mild tension between cosmic microwave background predictions from Planck mission and cosmic growth measurements at low redshift (z &amp;lt; 2). Then we test alternative models allowing the variation of one single cosmological parameter at a time. In particular, we find a larger growth index than the one predicted by general relativity $\gamma =0.65^{+0.05}_{-0.04}$. However, also a standard model with total neutrino mass of 0.26 ± 0.10 eV provides a similarly accurate description of the current data. By simulating an additional data set consistent with next-generation dark-energy mission forecasts, we show that growth rate constraints at z &amp;gt; 1 will be crucial to discriminate between alternative models.