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We show how standard Newtonian N-body simulations can be interpreted in terms of the weak-field limit of general relativity by employing the recently developed Newtonian motion gauge. Our framework allows the inclusion of radiation…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-12 Christian Fidler , Thomas Tram , Cornelius Rampf , Robert Crittenden , Kazuya Koyama , David Wands

Observables of cosmic structures are usually not the underlying matter field but biased tracers of matter, such as galaxies or halos. We show how the bias found in Newtonian N-body simulations can be interpreted in terms of the weak-field…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-26 Christian Fidler , Nils Sujata , Cornelius Rampf

We present a framework for general relativistic N-body simulations in the regime of weak gravitational fields. In this approach, Einstein's equations are expanded in terms of metric perturbations about a Friedmann-Lema\^itre background,…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-18 Julian Adamek , Ruth Durrer , Martin Kunz

We present a numerical weak-lensing analysis that is fully relativistic and non-perturbative for the scalar part of the gravitational potential and first-order in the vector part, frame dragging. Integrating the photon geodesics backwards…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-26 Francesca Lepori , Julian Adamek , Ruth Durrer , Chris Clarkson , Louis Coates

We present $N$-body simulations in which either all, or a fraction of, the cold dark matter decays non-relativistically to a relativistic, non-interacting dark radiation component. All effects from radiation and general relativity are…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-19 Jeppe Dakin , Steen Hannestad , Thomas Tram

Initial conditions for (Newtonian) cosmological N-body simulations are usually set by re-scaling the present-day power spectrum obtained from linear (relativistic) Boltzmann codes to the desired initial redshift of the simulation. This…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-28 Christian Fidler , Thomas Tram , Cornelius Rampf , Robert Crittenden , Kazuya Koyama , David Wands

We present $N$-body simulations which are fully compatible with general relativity, with dark energy consistently included at both the background and perturbation level. We test our approach for dark energy parameterised as both a fluid,…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-21 Jeppe Dakin , Steen Hannestad , Thomas Tram , Mischa Knabenhans , Joachim Stadel

This is the first in a series of papers devoted to fully general-relativistic $N$-body simulations applied to late-time cosmology. The purpose of this paper is to present the combination of a numerical relativity scheme, discretization…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-29 David Daverio , Yves Dirian , Ermis Mitsou

We introduce the N-body simulation technique to follow structure formation in linear and nonlinear regimes for the extended quintessence models (scalar-tensor theories in which the scalar field has a self-interaction potential and behaves…

Cosmology and Nongalactic Astrophysics · Physics 2012-07-04 Baojiu Li , David F. Mota , John D. Barrow

On large-scales, comparable to the horizon, the observable clustering properties of galaxies are affected by various general relativistic effects. To calculate these effects one needs to consistently solve for the metric, densities and…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-21 Nora Elisa Chisari , Matias Zaldarriaga

Contrary to recent claims in the literature, Newtonian N-body simulations of collisionless Dark Matter in a LambdaCDM background are compatible with general relativity and are not invalidated by general relativistic effects at the linear…

Cosmology and Nongalactic Astrophysics · Physics 2012-11-02 Thomas Haugg , Stefan Hofmann , Michael Kopp

In this communication we discuss the Weak Field Approach, and in particular the Newtonian limit, applied to f(R)-Gravity. Particular emphasis is placed on the spherically symmetric solutions and finally, it is clearly shown that General…

General Relativity and Quantum Cosmology · Physics 2010-10-04 A. Stabile , S. Capozziello

Within a cosmological context, we study the behaviour of collisionless particles in the weak field approximation to General Relativity, allowing for large gradients of the fields and relativistic velocities for the particles. We consider a…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-03 Julian Adamek , Mateja Gosenca , Shaun Hotchkiss

The standard numerical tools for studying non-linear collapse of matter are Newtonian $N$-body simulations. Previous work has shown that these simulations are in accordance with General Relativity (GR) up to first order in perturbation…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-07 Christian Fidler , Thomas Tram , Cornelius Rampf , Robert Crittenden , Kazuya Koyama , David Wands

We use gauge-invariant cosmological perturbation theory to calculate the displacement field that sets the initial conditions for $N$-body simulations. Using first and second-order fully relativistic perturbation theory in the…

General Relativity and Quantum Cosmology · Physics 2016-03-02 Adam J. Christopherson , Juan Carlos Hidalgo , Cornelius Rampf , Karim A. Malik

We present the first calculation of an intrinsically relativistic quantity in fully non-linear cosmolog- ical large-scale structure studies. Traditionally, non-linear structure formation in standard {\Lambda}CDM cosmology is studied using…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-26 Marco Bruni , Daniel B. Thomas , David Wands

Until now, it has been common to use Newton's gravity to study the non-linear clustering properties of the large-scale structures. Without confirmation from Einstein's theory, however, it has been unclear whether we can rely on the…

Astrophysics · Physics 2009-11-11 J. Hwang , H. Noh

The initial conditions for Newtonian $N$-body simulations are usually generated by applying the Zel'dovich approximation to the initial displacements of the particles using an initial power spectrum of density fluctuations generated by an…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-23 Christian Fidler , Cornelius Rampf , Thomas Tram , Robert Crittenden , Kazuya Koyama , David Wands

In this paper we examine cosmological weak lensing on non-linear scales and show that there are Newtonian and relativistic contributions and that the latter can also be extracted from standard Newtonian simulations. We use the…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-06 Daniel B. Thomas , Marco Bruni , David Wands

We present a novel method for including the impact of massive neutrinos in cold dark matter N-body simulations. Our approach is compatible with widely employed Newtonian N-body codes and relies on only three simple modifications. First, we…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-05 Pol Heuschling , Christian Partmann , Christian Fidler
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