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This paper introduces a systematic treatment of the linear theory of scalar gravitational perturbations in the presence of a fully inhomogeneous magnetic field. The analysis is conducted both in the synchronous and in the conformally…

Astrophysics · Physics 2009-11-10 Massimo Giovannini

We consider a test of the Copernican Principle through observations of the large-scale structures, and for this purpose we study the self-gravitating system in a relativistic huge void universe model which does not invoke the Copernican…

General Relativity and Quantum Cosmology · Physics 2016-12-14 Ryusuke Nishikawa , Ken-ichi Nakao , Chul-Moon Yoo

We present a method to introduce relativistic corrections including linear dark energy perturbations in Horndeski theory into Newtonian simulations based on the N-body gauge approach. We assume that standard matter species (cold dark…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-20 Guilherme Brando , Kazuya Koyama , David Wands

We describe the irrotational dust component of the universe in terms of a relativistic gradient expansion and transform the resulting synchronous metric to a Newtonian coordinate system. The two metrics are connected via a space-like…

Cosmology and Nongalactic Astrophysics · Physics 2013-08-06 Cornelius Rampf , Gerasimos Rigopoulos

Numerical simulations are a versatile tool providing insight into the complicated process of structure formation in cosmology. This process is mainly governed by gravity, which is the dominant force on large scales. To date, a century after…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-04 Julian Adamek , David Daverio , Ruth Durrer , Martin Kunz

We derive non-relativistic equations of motion for the formation of cosmological structure in a Scalar Field Dark Matter (SFDM) model corresponding to a complex scalar field endowed with a quadratic scalar potential. Starting with the full…

Cosmology and Nongalactic Astrophysics · Physics 2014-07-29 L. Arturo Urena-Lopez

In this note we approach the classical, Newtonian, gravitational $N$-body problem by mean of a new, original numerical integration method. After a short summary of the fundamental characteristics of the problem, including a sketch of some…

Computational Physics · Physics 2020-01-08 V. Parisi , R. Capuzzo-Dolcetta

In cosmological $N$-body simulations, the representation of dark matter as discrete "macroparticles" suppresses the growth of structure, such that simulations no longer reproduce linear theory on small scales near $k_{\rm Nyquist}$. Marcos…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-04 Lehman H. Garrison , Daniel J. Eisenstein , Douglas Ferrer , Marc V. Metchnik , Philip A. Pinto

We investigate cosmological predictions on the early universe based on the noncommutative geometry models of gravity coupled to matter. Using the renormalization group analysis for the Standard Model with right handed neutrinos and Majorana…

High Energy Physics - Theory · Physics 2009-08-27 Matilde Marcolli , Elena Pierpaoli

We present a systematic treatment of the linear theory of scalar gravitational perturbations in the synchronous gauge and the conformal Newtonian (or longitudinal) gauge. We first derive the transformation law relating the two gauges. We…

Astrophysics · Physics 2009-10-22 Chung-Pei Ma , Edmund Bertschinger

The development of numerical N -body simulations have allowed to study formation process and evolution of galaxies at different scales. This paper presents the fundamental concepts of N-body systems applied to the cosmological evolution of…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-12 Jazhiel Chacon , J. Alberto Vazquez , Ruslan Gabbasov

We perform N-body simulations for $f(T)$ gravity using the ME-Gadget code, in order to investigate for the first time the structure formation process in detail. Focusing on the power-law model, and considering the model-parameter to be…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-12 Yiqi Huang , Jiajun Zhang , Xin Ren , Emmanuel N. Saridakis , Yi-Fu Cai

We study in detail how neutrino perturbations can be followed in linear theory by using only terms up to $l=2$ in the Boltzmann hierarchy. We provide a new approximation to the third moment and demonstrate that the neutrino power spectrum…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-15 Maria Archidiacono , Steen Hannestad

We present the Aemulus $\nu$ simulations: a suite of 150 $(1.05 h^{-1}\rm Gpc)^3$ $N$-body simulations with a mass resolution of $3.51\times 10^{10} \frac{\Omega_{cb}}{0.3} ~ h^{-1} M_{\odot}$ in a $w\nu$CDM cosmological parameter space.…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-02 Joseph DeRose , Nickolas Kokron , Arka Banerjee , Shi-Fan Chen , Martin White , Risa Wechsler , Kate Storey-Fisher , Jeremy Tinker , Zhongxu Zhai

We present a general framework for obtaining robust bounds on the nature of dark matter using cosmological $N$-body simulations and Lyman-alpha forest data. We construct an emulator of hydrodynamical simulations, which is a flexible,…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-23 Keir K. Rogers , Hiranya V. Peiris

In this paper we present preliminary results from cosmological simulations of modified gravity in the dark matter sector. Our results show improvements over standard cold dark matter cosmology. The abundance of low-mass haloes in the…

Astrophysics · Physics 2008-07-08 Wojciech A. Hellwing

We show that, in the presence of massive neutrinos, the Galileon gravity model provides a very good fit to the current CMB temperature, CMB lensing and BAO data. This model, which we dub ${\nu} \rm{Galileon}$, when assuming its stable…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Alexandre Barreira , Baojiu Li , Carlton Baugh , Silvia Pascoli

We study the dynamics of small inhomogeneities in an expanding universe collapsing to form bound structures using full solutions of the Einstein-Vlasov (N-body) equations. We compare these to standard Newtonian N-body solutions using…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-28 William E. East , Radosław Wojtak , Frans Pretorius

We show how the relativistic matter and velocity power spectra behave in different gauges. We construct a new gauge where both spectra coincide with Newtonian theory on all scales. However, in this gauge there are geometric quantities…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Samuel F. Flender , Dominik J. Schwarz

The cosmic large-scale structure (LSS) provides a unique testing ground for connecting fundamental physics to astronomical observations. Modeling the LSS requires numerical $N$-body simulations or perturbative techniques that both come with…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-20 Florian List , Oliver Hahn , Cornelius Rampf