A direct probe of cosmological power spectra of the peculiar velocity field and the gravitational lensing magnification from photometric redshift surveys

The physics of gravity on cosmological scales affects both the rate of assembly of large-scale structure and the gravitational lensing of background light through this cosmic web. By comparing the amplitude of these different observational signatures, we can construct tests that can distinguish general relativity from its potential modifications. We used the latest weak gravitational lensing dataset from the Kilo-Degree Survey, KiDS-1000, in conjunction with overlapping galaxy spectroscopic redshift surveys, BOSS and 2dFLenS, to perform the most precise existing amplitude-ratio test. We measured the associated EG statistic with 15 − 20% errors in five Δz = 0.1 tomographic redshift bins in the range 0.2 < z < 0.7 on projected scales up to 100 h−1 Mpc. The scale-independence and redshift-dependence of these measurements are consistent with the theoretical expectation of general relativity in a Universe with matter density Ωm = 0.27 ± 0.04. We demonstrate that our results are robust against different analysis choices, including schemes for correcting the effects of source photometric redshift errors, and we compare the performance of angular and projected galaxy-galaxy lensing statistics.

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1403 ◽

2019 ◽

Vol 487 (4) ◽

pp. 5209-5234 ◽

Cited By ~ 4

Author(s):

Cullan Howlett

Keyword(s):

Power Spectrum ◽

Measurement Errors ◽

Cosmological Parameters ◽

Power Spectra ◽

Optimal Estimation ◽

Peculiar Velocity ◽

Optimal Weights ◽

Peculiar Velocities ◽

Redshift Surveys ◽

The Galaxy

Abstract 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 (PV) 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 PV 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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Testing the peculiar velocity field predicted from redshift surveys

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/268.4.943 ◽

1994 ◽

Vol 268 (4) ◽

pp. 943-952 ◽

Cited By ~ 8

Author(s):

W. Freudling ◽

L. Nicolaci da Costa ◽

P. S. Pellegrini

Keyword(s):

Velocity Field ◽

Peculiar Velocity ◽

Redshift Surveys

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Measuring the cosmic bulk flow with 6dFGSv

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316010115 ◽

2014 ◽

Vol 11 (S308) ◽

pp. 336-339 ◽

Cited By ~ 1

Author(s):

Christina Magoulas ◽

Christopher Springob ◽

Matthew Colless ◽

Jeremy Mould ◽

John Lucey ◽

...

Keyword(s):

Velocity Field ◽

Large Scale ◽

Cosmological Parameters ◽

Distortion Parameter ◽

Peculiar Velocity ◽

Peculiar Velocities ◽

Redshift Surveys ◽

Luminous Matter ◽

The Galaxy ◽

Space Distortion

AbstractWhile recent years have seen rapid growth in the number of galaxy peculiar velocity measurements, disagreements remain about the extent to which the peculiar velocity field - a tracer of the large-scale distribution of mass - agrees with both ΛCDM expectations and with velocity field models derived from redshift surveys. The 6dF Galaxy Survey includes peculiar velocities for nearly 9 000 early-type galaxies (6dFGSv), making it the largest and most homogeneous galaxy peculiar velocity sample to date. We have used the 6dFGS velocity field to determine the amplitude and scale of large-scale cosmic flows in the local universe and test standard cosmological models. We also compare the galaxy density and peculiar velocity fields to establish the distribution of dark and luminous matter and better constrain key cosmological parameters such as the redshift-space distortion parameter.

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