### Abstract

Measurements of the growth rate of structure, f sigma(8), in the low-redshift Universe allow stringent tests of the cosmological model. In this work, we provide new constraints on f sigma(8) at an effective redshift of z= 0.03 using the combined density and velocity fields measured by the 2MTF and 6dFGSv surveys. We do this by applying a new estimator of the redshift-space density and momentum (density-weighted velocity) power spectra, developed in the first paper of this series, to measured redshifts and peculiar velocities from these data sets. We combine this with models of the density and momentum power spectra in the presence of complex survey geometries and with an ensemble of simulated galaxy catalogues that match the survey selection functions and galaxy bias. We use these simulations to estimate the errors on our measurements and identify possible systematics. In particular, we are able to identify and remove biases caused by the non-Gaussianity of the power spectra by applying the Box-Cox transformation to the power spectra prior to fitting. After thorough validation of our methods we recover a constraint of from the combined 2MTF and 6dFGSv data. This measurement is fully consistent with the expectations of general relativity and the Lambda cold dark matter cosmological model. It is also comparable and complementary to constraints using different techniques on similar data, affirming the usefulness of our method for extracting cosmology from velocity fields.

Original language | English |
---|---|

Pages (from-to) | 5235-5247 |

Number of pages | 13 |

Journal | Monthly Notices of the Royal Astronomical Society |

Volume | 487 |

Issue number | 4 |

DOIs | |

Publication status | Published - Aug 2019 |

### Cite this

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**The redshift-space momentum power spectrum - II. Measuring the growth rate from the combined 2MTF and 6dFGSv surveys.** / Qin, Fei; Howlett, Cullan; Staveley-Smith, Lister.

Research output: Contribution to journal › Article

TY - JOUR

T1 - The redshift-space momentum power spectrum - II. Measuring the growth rate from the combined 2MTF and 6dFGSv surveys

AU - Qin, Fei

AU - Howlett, Cullan

AU - Staveley-Smith, Lister

PY - 2019/8

Y1 - 2019/8

N2 - Measurements of the growth rate of structure, f sigma(8), in the low-redshift Universe allow stringent tests of the cosmological model. In this work, we provide new constraints on f sigma(8) at an effective redshift of z= 0.03 using the combined density and velocity fields measured by the 2MTF and 6dFGSv surveys. We do this by applying a new estimator of the redshift-space density and momentum (density-weighted velocity) power spectra, developed in the first paper of this series, to measured redshifts and peculiar velocities from these data sets. We combine this with models of the density and momentum power spectra in the presence of complex survey geometries and with an ensemble of simulated galaxy catalogues that match the survey selection functions and galaxy bias. We use these simulations to estimate the errors on our measurements and identify possible systematics. In particular, we are able to identify and remove biases caused by the non-Gaussianity of the power spectra by applying the Box-Cox transformation to the power spectra prior to fitting. After thorough validation of our methods we recover a constraint of from the combined 2MTF and 6dFGSv data. This measurement is fully consistent with the expectations of general relativity and the Lambda cold dark matter cosmological model. It is also comparable and complementary to constraints using different techniques on similar data, affirming the usefulness of our method for extracting cosmology from velocity fields.

AB - Measurements of the growth rate of structure, f sigma(8), in the low-redshift Universe allow stringent tests of the cosmological model. In this work, we provide new constraints on f sigma(8) at an effective redshift of z= 0.03 using the combined density and velocity fields measured by the 2MTF and 6dFGSv surveys. We do this by applying a new estimator of the redshift-space density and momentum (density-weighted velocity) power spectra, developed in the first paper of this series, to measured redshifts and peculiar velocities from these data sets. We combine this with models of the density and momentum power spectra in the presence of complex survey geometries and with an ensemble of simulated galaxy catalogues that match the survey selection functions and galaxy bias. We use these simulations to estimate the errors on our measurements and identify possible systematics. In particular, we are able to identify and remove biases caused by the non-Gaussianity of the power spectra by applying the Box-Cox transformation to the power spectra prior to fitting. After thorough validation of our methods we recover a constraint of from the combined 2MTF and 6dFGSv data. This measurement is fully consistent with the expectations of general relativity and the Lambda cold dark matter cosmological model. It is also comparable and complementary to constraints using different techniques on similar data, affirming the usefulness of our method for extracting cosmology from velocity fields.

KW - galaxies: statistics

KW - cosmological parameters

KW - large-scale structure of Universe

KW - GALAXY SURVEY

KW - BULK FLOW

KW - PECULIAR VELOCITIES

KW - PARAMETER INFERENCE

KW - FUNDAMENTAL PLANE

KW - COSMIC FLOWS

KW - DATA SET

KW - DENSITY

KW - CONSTRAINTS

KW - FIELD

U2 - 10.1093/mnras/stz1576

DO - 10.1093/mnras/stz1576

M3 - Article

VL - 487

SP - 5235

EP - 5247

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -