Jennings, E and Jennings, D orcid.org/0000-0003-1201-3725 (2015) Non-linear stochastic growth rates and redshift space distortions. Monthly Notices of the Royal Astronomical Society, 449 (4). pp. 3407-3419. ISSN 0035-8711
Abstract
The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a non-linear, stochastic relation between θ=∇⋅v(x,t)/aH and δ. This provides a new phenomenological approach that examines the conditional mean 〈θ|δ〉, together with the fluctuations of θ around this mean. We measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ∼10 per cent at k < 0.2 h Mpc−1 to 25 per cent at k ∼ 0.45 h Mpc−1 at z = 0. Both the stochastic relation and non-linearity are more pronounced for haloes, M ≤ 5 × 1012 M⊙ h−1, compared to the dark matter at z = 0 and 1. Non-linear growth effects manifest themselves as a rotation of the mean 〈θ|δ〉 away from the linear theory prediction −fLTδ, where fLT is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second-order Lagrangian perturbation theory (2LPT) for k < 0.1 h Mpc−1. The stochasticity in the θ–δ relation is not so simply described by 2LPT, and we discuss its impact on measurements of fLT from two-point statistics in redshift space. Given that the relationship between δ and θ is stochastic and non-linear, this will have implications for the interpretation and precision of fLT extracted using models which assume a linear, deterministic expression.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | Published by Oxford University Press on behalf of The Royal Astronomical Society 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US. This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Keywords: | cosmology: theory, large-scale structure of Universe |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Theoretical Physics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 03 Jan 2019 15:40 |
Last Modified: | 03 Jan 2019 15:40 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | 10.1093/mnras/stv535 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:139392 |