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Related papers: $k$-evolution: a relativistic N-body code for clus…

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We present KGB-evolution, a relativistic $N$-body simulation code that extends the $k$-evolution code by incorporating an effective field theory parameterization of kinetic gravity braiding, while also including the $k$-essence model as a…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-07 Ahmad Nouri-Zonoz , Farbod Hassani , Emilio Bellini , Martin Kunz

In this paper, we study the effective field theory (EFT) of dark energy for the $k$-essence model beyond linear order. Using particle-mesh $N$-body simulations that consistently solve the dark energy evolution on a grid, we find that the…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-19 Farbod Hassani , Julian Adamek , Martin Kunz , Pan Shi , Peter Wittwer

We present a new N-body code, gevolution, for the evolution of large scale structure in the Universe. Our code is based on a weak field expansion of General Relativity and calculates all six metric degrees of freedom in Poisson gauge.…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-05 Julian Adamek , David Daverio , Ruth Durrer , Martin Kunz

In this paper, we quantify the non-linear effects from $k$-essence dark energy through an effective parameter $\mu$ that encodes the additional contribution of a dark energy fluid or a modification of gravity to the Poisson equation. This…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-23 Farbod Hassani , Benjamin L'Huillier , Arman Shafieloo , Martin Kunz , Julian Adamek

We investigate the non-linear evolution of spherical density and velocity perturbations of dark matter and dark energy in the expanding Universe. For that we have used the conservation and Einstein equations to describe the evolution of…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-04 M. Tsizh , B. Novosyadlyj

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

Some of the dark matter in the Universe is made up of massive neutrinos. Their impact on the formation of large scale structure can be used to determine their absolute mass scale from cosmology, but to this end accurate numerical…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-09 Julian Adamek , Ruth Durrer , Martin Kunz

We review dark energy models which can present non-negligible fluctuations on scales smaller than Hubble radius. Both linear and nonlinear evolutions of dark energy fluctuations are discussed. The linear evolution has a well-established…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-27 Ronaldo C. Batista

We build an emulator based on the polynomial chaos expansion (PCE) technique to efficiently model the non-linear effects associated with the clustering of the $k$-essence dark energy in the effective field theory (EFT) framework. These…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-20 A. R. Nouri-Zonoz , F. Hassani , M. Kunz

Non-linear gravitational clustering in a universe dominated by dark energy, modelled by a `quintessence' scalar field, and cold dark matter with space-time varying mass is studied. Models of this type, where the variable mass is induced by…

Astrophysics · Physics 2009-11-07 S. Matarrese , M. Pietroni , C. Schimd

We consider a model of dark energy/matter unification based on a k-essence type of theory similar to tachyon condensate models. Using an extension of the general relativistic spherical model which incorporates the effects of both pressure…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Neven Bilic , Gary B. Tupper , Raoul D. Viollier

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

A ghost dark energy model has been recently put forward to explain the current accelerated expansion of the Universe. In this model, the energy density of ghost dark energy, which comes from the Veneziano ghost of QCD, is proportional to…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Alberto Rozas-Fernandez

N-body equations of motion in comoving system and expanding background are reformulated in a transformed system with static background and fixed damping. The energy and momentum evolution in dark matter flow are rigorously formulated for…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-22 Zhijie Xu

We investigate various dark energy models by taking into account the thermal effects induced from Hawking radiation on the apparent horizon of the Universe, for example near a finite-time future singularity. If the dark energy density…

General Relativity and Quantum Cosmology · Physics 2021-02-17 Artyom V. Astashenok , Sergei D. Odintsov , Vasilis K. Oikonomou

A dependence of the neutrino masses on the dark energy scalar field could provide a solution to the why now problem of dark energy. The dynamics of the resulting cosmological model, growing neutrino quintessence, include an attractive force…

Cosmology and Nongalactic Astrophysics · Physics 2012-07-11 Youness Ayaita , Maik Weber , Christof Wetterich

We consider a dark energy fluid with arbitrary sound speed and equation of state and discuss the effect of its clustering on the cold dark matter distribution at the non-linear level. We write the continuity, Euler and Poisson equations for…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-19 Stefano Anselmi , Guillermo Ballesteros , Massimo Pietroni

We present $\texttt{MG-evolution}$, an $N$-body code simulating the cosmological structure formation for parametrised modifications of gravity. It is built from the combination of parametrised linear theory with a parametrisation of the…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-03 Farbod Hassani , Lucas Lombriser

Relativistic effects are sensitive to subtle changes in dark energy. These effects grow on very large scales and at high redshifts, which will be the reach of upcoming surveys. We investigate these effects in both the linear and the angular…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-24 Didam Duniya , Isaac Opio , Bishop Mongwane , Hassan Abdalla

In this work, we propose a scheme for cosmic evolution in a generalized Rastall gravity. In our approach, the role of dark energy is taken by the non-conserved sector of the stress energy-momentum tensor. The resultant cosmic evolution is…

General Relativity and Quantum Cosmology · Physics 2020-06-08 Kai Lin , Wei-Liang Qian
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