DEUS full observable universe simulations: Numerical challenge and outlooks

Reverdy, Vincent; Alimi, Jean‐Michel; Bouillot, Vincent; Corasaniti, Pier-Stefano; Balmès, Irène; St,; Requena, phane; Delaruelle, Xavier; Richet, Jean-Noel

doi:10.1177/1094342015576845

Cited by 9 publications

(12 citation statements)

References 18 publications

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“…Sorting the vertices this way ensures that two points near to each other in 3D are mapped to close indices. Hilbert sorting is classical in high performance large scale cosmological simulation, for instance, it is a key component of the code used in the DEUS project (Reverdy et al 2015). Figure A2-B,C shows what the computed order looks like for a homogeneous point distribution.…”

Section: Data Availabilitymentioning

confidence: 99%

A fast semidiscrete optimal transport algorithm for a unique reconstruction of the early Universe

Lévy

Mohayaee

Hausegger

2021

Monthly Notices of the Royal Astronomical Society

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We leverage powerful mathematical tools stemming from optimal transport theory and transform them into an efficient algorithm to reconstruct the fluctuations of the primordial density field, built on solving the Monge-Ampère-Kantorovich equation. Our algorithm computes the optimal transport between an initial uniform continuous density field, partitioned into Laguerre cells, and a final input set of discrete point masses, linking the early to the late Universe. While existing early universe reconstruction algorithms based on fully discrete combinatorial methods are limited to a few hundred thousand points, our algorithm scales up well beyond this limit, since it takes the form of a well-posed smooth convex optimization problem, solved using a Newton method. We run our algorithm on cosmological N-body simulations, from the AbacusCosmos suite, and reconstruct the initial positions of $\mathcal {O}(10^7)$ particles within a few hours with an off-the-shelf personal computer. We show that our method allows a unique, fast and precise recovery of subtle features of the initial power spectrum, such as the baryonic acoustic oscillations.

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Section: Data Availabilitymentioning

confidence: 99%

A fast semidiscrete optimal transport algorithm for a unique reconstruction of the early Universe

Lévy

Mohayaee

Hausegger

2021

Monthly Notices of the Royal Astronomical Society

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“…DEUS-FUR comprises three N-body simulations of a (21 Gpc/h) 3 volume with 8192 3 particles of a flat ΛCDM model and two DE scenarios with different expansion histories (see Table I). The simulations have been run using the application AMADEUS -'A Multi-purpose Application for Dark Energy Universe Simulation' expressively developed for the realization of the DEUS-FUR project [19,20]. This includes the code generating Gaussian initial conditions for which we use an optimized version of MPGRAFIC [31], the N-body solver for which we use a specifically modified version of the RAMSES code [32] such as to run on a very large number of cores (≈ 80000) and a parallel friends-of-friends halo finder pFoF as described in [33].…”

Section: B Simulationsmentioning

confidence: 99%

“…We also investigate the imprint of non-linearities on the CMB-LSS correlation and its cosmological dependence on the DE model. To this end we use the full-sky lightcone data from the Dark Energy Universe Simulation -Full Universe Runs (DEUS-FUR) [19,20] in combination with a sophisticated ray-tracing technique that solves the photon geodesic equations along the photon trajectory. Our approach takes advantage of the fact that the DEUS-FUR simulations cover the volume of the entire observable universe allowing to generate full-sky lightcone data without the need of recurring to any replica method.…”

Section: Introductionmentioning

confidence: 99%

Ray tracing the integrated Sachs-Wolfe effect through the light cones of the Dark Energy Universe Simulation -- Full Universe Runs

Adamek,

Rasera,

Corasaniti

et al. 2019

Preprint

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The late integrated Sachs-Wolfe (ISW) effect correlates the Cosmic Microwave Background (CMB) temperature anisotropies with foreground cosmic large-scale structures. As the correlation depends crucially on the growth history in the era of dark energy, it is a key observational probe for constraining the cosmological model. Here we present a detailed study based on full-sky and deep light cones generated from very large volume numerical N-body simulations, which allow us to avoid the use of standard replica techniques, while capturing the entirety of the late ISW effect on the large scales. We post-process the light cones using an accurate ray-tracing method and construct full-sky maps of the ISW temperature anisotropy for three different dark energy models. We quantify in detail the extent to which the ISW effect can be used to discriminate between different dark energy scenarios when cross-correlated with the matter distribution or the CMB lensing potential. We also investigate the onset of non-linearities, the so-called Rees-Sciama effect which provides a complementary probe of the dark sector. We find the signal of the lensing-lensing and ISW-lensing correlation of the three dark energy models to be consistent with measurements from the Planck satellite. Future surveys of the large scale structures may provide cross-correlation measurements that are sufficiently precise to distinguish the signal of these models. Our methodology is very general and can be applied to any dark energy or modified gravity scenario.

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“…They consist of N-body simulations of Dark Matter (DM) for realistic dark energy models. For more details we refer the interested reader to dedicated sections in Alimi et al (2010); Rasera et al (2010); Courtin et al (2010); Alimi et al (2012); Reverdy et al (2015). These simulations have been realized with an optimized version (Alimi et al 2012;Reverdy et al 2015) of the adaptive mesh refinement code RAMSES based on a multigrid Poisson solver (Teyssier 2002;Guillet & Teyssier 2011) for Gaussian initial conditions generated using the Zel'dovich approximation with MPGRAFIC code (Prunet et al 2008) and input linear power spectrum from CAMB (Lewis et al 2000).…”

Section: N-body Deus Simulationsmentioning

confidence: 99%

Reconstructing matter profiles of spherically compensated cosmic regions in ΛCDM cosmology

Fromont

Alimi

2017

Monthly Notices of the Royal Astronomical Society

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The absence of a physically motivated model for large scale profiles of cosmic voids limits our ability to extract valuable cosmological information from their study. In this paper, we address this problem by introducing the spherically compensated cosmic regions, named CoSpheres. Such cosmic regions are identified around local extrema in the density field and admit a unique compensation radius R 1 where the internal spherical mass is exactly compensated. Their origin is studied by extending the standard peak model and implementing the compensation condition. Since the compensation radius evolves as the Universe itself, R 1 (t) ∝ a(t), CoSpheres behave as bubble Universes with fixed comoving volume. Using the spherical collapse model, we reconstruct their profiles with a very high accuracy until z = 0 in N-body simulations. CoSpheres are symmetrically defined and reconstructed for both central maximum (seeding haloes and galaxies) and minimum (identified with cosmic voids). We show that the full non linear dynamics can be solved analytically around this particular compensation radius, providing useful predictions for cosmology. This formalism highlights original correlations between local extremum and their large scale cosmic environment. The statistical properties of these spherically compensated cosmic regions and the possibilities to constrain efficiently both cosmology and gravity will be investigated in companion papers.

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DEUS full observable universe simulations: Numerical challenge and outlooks

Cited by 9 publications

References 18 publications

A fast semidiscrete optimal transport algorithm for a unique reconstruction of the early Universe

A fast semidiscrete optimal transport algorithm for a unique reconstruction of the early Universe

Ray tracing the integrated Sachs-Wolfe effect through the light cones of the Dark Energy Universe Simulation -- Full Universe Runs

Reconstructing matter profiles of spherically compensated cosmic regions in ΛCDM cosmology

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