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A new way of setting the phases for cosmological multiscale Gaussian initial conditions

Jenkins, Adrian

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Abstract

We describe how to define an extremely large discrete realization of a Gaussian white noise field that has a hierarchical structure and the property that the value of any part of the field can be computed quickly. Tiny subregions of such a field can be used to set the phase information for Gaussian initial conditions for individual cosmological simulations of structure formation. This approach has several attractive features: (i) the hierarchical structure based on an octree is particularly well suited for generating follow-up resimulation or zoom initial conditions; (ii) the phases are defined for all relevant physical scales in advance so that resimulation initial conditions are, by construction, consistent both with their parent simulation and with each other; (iii) the field can easily be made public by releasing a code to compute it – once public, phase information can be shared or published by specifying a spatial location within the realization. In this paper, we describe the principles behind creating such realizations. We define an example called Panphasia and in a companion paper by Jenkins and Booth (2013) make public a code to compute it. With 50 octree levels Panphasia spans a factor of more than 1015 in linear scale – a range that significantly exceeds the ratio of the current Hubble radius to the putative cold dark matter free-streaming scale. We show how to modify a code used for making cosmological and resimulation initial conditions so that it can take the phase information from Panphasia and, using this code, we demonstrate that it is possible to make good quality resimulation initial conditions. We define a convention for publishing phase information from Panphasia and publish the initial phases for several of the Virgo Consortium's most recent cosmological simulations including the 303 billion particle MXXL simulation. Finally, for reference, we give the locations and properties of several dark matter haloes that can be resimulated within these volumes.

Citation

Jenkins, A. (2013). A new way of setting the phases for cosmological multiscale Gaussian initial conditions. Monthly Notices of the Royal Astronomical Society, 434(3), 2094-2120. https://doi.org/10.1093/mnras/stt1154

Journal Article Type Article
Publication Date Sep 1, 2013
Deposit Date Sep 13, 2013
Publicly Available Date Mar 29, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 434
Issue 3
Pages 2094-2120
DOI https://doi.org/10.1093/mnras/stt1154
Keywords Numerical methods, Cosmology theory.

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2013 The Author. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.





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