Cosmological forecasts for combined and next-generation peculiar velocity surveys

Howlett, Cullan; Staveley‐Smith, L.; Blake, Chris

doi:10.1093/mnras/stw2466

Cited by 66 publications

(81 citation statements)

References 108 publications

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“…Note that, however, in observations such as peculiar velocity and kSZ surveys, the velocity field is also sampled in redshift space, thus affected by redshiftspace distortions (RSD) [99], as formulated by Refs. [85,90,100]. The effect of RSD on the alignment clustering statistics has been studied by Refs.…”

Section: Discussionmentioning

confidence: 99%

Intrinsic alignment statistics of density and velocity fields at large scales: Formulation, modeling, and baryon acoustic oscillation features

2019

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The kinematic Sunyaev-Zel'dovich effect enables us to directly probe the density-weighted velocity field up to very large cosmic scales. We investigate the effects of intrinsic alignments (IA) of darkmatter halo shapes on cosmic density and velocity fields on such large scales. In literature IA have been detected up to ∼ 100 h −1 Mpc using the gravitational shear-intrinsic ellipticity (GI) correlation and the alignment correlation function. In this paper we introduce the corresponding various velocity statistics: the (density-weighted) velocity-intrinsic ellipticity (VI) correlation as well as the alignment pairwise infall momentum, momentum correlation function, and density-weighted pairwise velocity dispersion. We derive theoretical expressions for these velocity alignment statistics for the first time based on the assumption that the density fluctuation is a Gaussian random field. Using large-volume, high-resolution N -body simulations, we measure the alignment statistics of density and velocity fields. Behaviors of IA in the velocity statistics are similar to those in the density statistics, except that the halo orientations are aligned with the velocity field up to scales larger than those with the density field, r 100 h −1 Mpc, because of a factor of the wavenumber in the linear relation between the density and velocity fields in Fourier space, v ∝ δ/k. We show that the detected IA of the velocity field can be well predicted by the linear alignment model. We also demonstrate that the baryon acoustic oscillation features can be detected in both the conventional and alignment velocity statistics. Our results indicate that observations of IA with the velocity field on large scales can provide additional information on cosmological models, complementary to those with the density field.

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Section: Discussionmentioning

confidence: 99%

Intrinsic alignment statistics of density and velocity fields at large scales: Formulation, modeling, and baryon acoustic oscillation features

2019

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“…momentum p, power spectrum, which may contain less) and so instead of the models in Appendix A, we use models for the density, velocity and cross power spectrum from Koda et al (2014); Howlett et al (2017a) P δ (k, µ) = (b1 + f µ 2 ) 2 D 2 g PL(k), P δu (k, µ) = (b1 + f µ 2 )DgDu iaHf µ k PL(k), P u (k, µ) = aHf µ k 2 D 2 u PL(k) (B5)…”

Section: Discussionmentioning

confidence: 99%

The redshift-space momentum power spectrum – I. Optimal estimation from peculiar velocity surveys

Howlett

2019

Monthly Notices of the Royal Astronomical Society

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Low redshift surveys of galaxy peculiar velocities provide a wealth of cosmological information. We revisit the idea of extracting this information by directly measuring the redshift-space momentum power spectrum from such surveys. We provide a comprehensive theoretical and practical framework for estimating and fitting this from data, analogous to well understood techniques used to measure the galaxy density power spectrum from redshift surveys. We formally derive a new estimator, which includes the effects of shot noise and survey geometry; we evaluate the variance of the estimator in the Gaussian regime; we compute the optimal weights for the estimator; we demonstrate that the measurements are Gaussian distributed, allowing for easy extraction of cosmological parameters; and we explore the effects of peculiar velocity measurement errors. We finish with a proof-of-concept using realistic mock galaxy catalogues, which demonstrates that we can measure and fit both the redshift-space galaxy density and momentum power spectra from peculiar velocity surveys and that including the latter substantially improves our constraints on the growth rate of structure. We also provide theoretical descriptions for modelling the non-linear redshift-space density and momentum power spectrum multipoles, and forecasting the constraints on cosmological parameters using the Fisher information contained in these measurements for arbitrary weights. These may be useful for measurements of the galaxy density power spectrum even in the absence of peculiar velocities.

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“…, f D n b , bD} for n b redshift bins. This model is commonly used to project and report the results of peculiar velocity surveys [22].…”

Section: Surveys and Methodsmentioning

confidence: 99%

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

Kim

Linder

2020

Phys. Rev. D

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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 multiobject 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 σ8 at z 0.2 where density tracers cannot do better than ∼ 10%. 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 σ(γ) ≈ 0.02, 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 ΛCDM model assumption to a w0-wa cosmology.

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Cosmological forecasts for combined and next-generation peculiar velocity surveys

Cited by 66 publications

References 108 publications

Intrinsic alignment statistics of density and velocity fields at large scales: Formulation, modeling, and baryon acoustic oscillation features

Intrinsic alignment statistics of density and velocity fields at large scales: Formulation, modeling, and baryon acoustic oscillation features

The redshift-space momentum power spectrum – I. Optimal estimation from peculiar velocity surveys

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

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