Constrained realizations of 2MRS density and peculiar velocity fields: growth rate and local flow
Abstract
We generate constrained realizations (CRs) of the density and peculiar velocity fields within $200 \, h^{1} \, \mathrm{Mpc}$ from the final release of the TwoMicron AllSky Redshift Survey (2MRS)  the densest allsky redshift survey to date. The CRs are generated by combining a Wiener filter estimator in spherical FourierBessel space with random realizations of lognormally distributed density fields and Poissonsampled galaxy positions. The algorithm is tested and calibrated on a set of semianalytic mock catalogues mimicking the environment of the Local Group (LG), to rigorously account for the statistical and systematic errors of the reconstruction method. By comparing our peculiar velocity CRs with the observed velocities from the Cosmicflows3 catalogue, we constrain the normalized linear growth rate to $f \sigma _8^{\text{lin}}= 0.367 \pm 0.060$, which is consistent at the 1.1σ level with the latest Planck results as well as other direct probes. Simultaneously, we estimate a bulk flow contribution from sources beyond the 2MRS reconstruction volume of $B^{\text{ext}}= 199 \pm 68 \, \mathrm{km} \, \mathrm{s}^{1}$ towards l = 299 ± 18°, b = 8 ± 19°. The total reconstructed velocity field at the position of the LG, smoothed with a $1 \, h^{1} \, \mathrm{Mpc}$ Gaussian, is $685 \pm 75 \, \mathrm{km} \, \mathrm{s}^{1}$ towards l = 270.6 ± 6.6°, b = 35.5 ± 7.2°, in good agreement with the observed CMB dipole. The total reconstructed bulk flow within different radii is compatible with other measurements. Within a $50 \, h^{1} \, \mathrm{Mpc}$ Gaussian window we find a bulk flow of $274 \pm 50 \, \mathrm{km} \, \mathrm{s}^{1}$ towards l = 287 ± 9°, b = 11 ± 10°. The code used to generate the CRs and obtain these results, dubbed CORAS, is made publicly available.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 October 2021
 DOI:
 10.1093/mnras/stab2009
 arXiv:
 arXiv:2102.07291
 Bibcode:
 2021MNRAS.507.1557L
 Keywords:

 galaxies: statistics;
 dark matter;
 largescale structure of Universe;
 cosmology: observations;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 Code and reconstructed fields available at https://github.com/rlilow/CORAS . Reconstructed peculiar velocities of Cosmicflows3 galaxies and groups available at http://edd.ifa.hawaii.edu . Changes in v2: small improvements to analysis and calibration, extended some discussions, mock test moved from appendix to main body, other minor corrections. v2 matches accepted version