Abstract
Abstract A hierarchical Bayesian model is applied to the Cosmicflows-3 catalogue of galaxy distances in order to derive the peculiar velocity field and distribution of matter within z ∼ 0.054. The model assumes the ΛCDM model within the linear regime and includes the fit of the galaxy distances together with the underlying density field. By forward modelling the data, the method is able to mitigate biases inherent to peculiar velocity analyses, such as the Homogeneous Malmquist bias or the lognormal distribution of peculiar velocities. The statistical uncertainty on the recovered velocity field is about 150 km s−1 depending on the location, and we study systematics coming from the selection function and calibration of distance indicators. The resulting velocity field and related density fields recover the cosmography of the Local Universe which is presented in an unprecedented volume of our Universe 10 times larger than previously reached. This methodology opens the doors to reconstruction of initial conditions for larger and more accurate constrained cosmological simulations. This work is also preparatory to larger peculiar velocity data sets coming from Wallaby, TAIPAN, or LSST.
Highlights
Peculiar motions of galaxies are due to the gravitational interaction with the underlying density field of matter
The Local Universe peculiar velocity field has been reconstructed from the expected response to the observed redshift distribution of galaxies taken as tracers of the mass distribution (Hudson et al E-mail romain.graziani@clermont.in2p3.fr (RG); h.courtois@ipnl.in2p3.fr (HMC)
The assumption is made with the Wiener Filter/Constrained Realizations methodology (WF/CR) methodology that the measured velocities have a Gaussian noise and that their two-point correlations are given by the Lambda cold dark matter ( CDM) model
Summary
Peculiar motions of galaxies are due to the gravitational interaction with the underlying density field of matter. Peculiar velocities of galaxies are a powerful and unbiased tool to study the dynamics and structure of the Local Universe. The Local Universe peculiar velocity field has been reconstructed from the expected response to the observed redshift distribution of galaxies taken as tracers of the mass distribution (Hudson et al.2004; Nusser & Davis 2011; Davis & Scrimgeour 2014; Hong et al 2014; Scrimgeour et al 2016). Cosmicflows catalogues (Tully et al 2008, 2013) have been analysed through the Wiener Filter/Constrained Realizations methodology (WF/CR; Zaroubi, Hoffman & Dekel 1999; Courtois et al 2012). The assumption is made with the WF/CR methodology that the measured velocities have a Gaussian noise and that their two-point correlations are given by the Lambda cold dark matter ( CDM) model
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