Parametrising non-linear dark energy perturbations

Hassani, Farbod; L’Huillier, Benjamin; Shafieloo, Arman; Kunz, M.; Adamek, Julian

doi:10.1088/1475-7516/2020/04/039

Cited by 21 publications

(17 citation statements)

References 28 publications

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“…Thus, let us consider the perturbation condition by means of the adiabatic sound speed, c s , i.e., we assume the sound speed definition in adiabatic perturbations, in analogy to what happens in fluid dynamics [39,40]. So, defining the adiabatic sound speed by [41][42][43]:…”

Section: The Stability Condition and The Sound Speedmentioning

confidence: 99%

Traversable wormholes with vanishing sound speed in f(R) gravity

2021

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We derive exact traversable wormhole solutions in the framework of f(R) gravity with no exotic matter and with stable conditions over the geometric fluid entering the throat. For this purpose, we propose power-law f(R) models and two possible approaches for the shape function b(r)/r. The first approach makes use of an inverse power-law function, namely $$b(r)/r\sim r^{-1-\beta }$$ b ( r ) / r ∼ r - 1 - β . The second one adopts Padé approximants, used to characterize the shape function in a model-independent way. We single out the P(0, 1) approximant where the fluid perturbations are negligible within the throat, if the sound speed vanishes at $$r=r_0$$ r = r 0 . The former guarantees an overall stability of the geometrical fluid into the wormhole. Finally, we get suitable bounds over the parameters of the model for the above discussed cases. In conclusion, we find that small deviations from general relativity give stable solutions.

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Section: The Stability Condition and The Sound Speedmentioning

confidence: 99%

Traversable wormholes with vanishing sound speed in f(R) gravity

2021

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“…Here, the ratio P DE /P m is more suppressed in k-evolution than in CLASS, as the matter non-linearity is more effective than dark energy non-linearity, while inside the sound-horizon (on the very right of the left-hand panel, for redshifts, z = 0 and z = 1) we see the k-evolution result becoming larger than the one of CLASS, due to the effective clustering of dark energy at those scales. A more detailed study of the power ratio can be found in a companion paper [33].…”

Section: K-evolution Versus Classmentioning

confidence: 99%

“…Using the back-scaling approach it is not possible to obtain good results for both the matter density and the gravitational potential simultaneously. In a related paper [33] we present a possible approach to include a correction for the gravitational potential that addresses this problem.…”

Section: Newtonian Simulations With "Back-scaled" Initial Conditionsmentioning

confidence: 99%

k-evolution: a relativistic N-body code for clustering dark energy

Hassani

Adamek

Kunz

et al. 2019

J. Cosmol. Astropart. Phys.

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We introduce k-evolution, a relativistic N -body code based on gevolution, which includes clustering dark energy among its cosmological components. To describe dark energy, we use the effective field theory approach. In particular, we focus on k-essence with a speed of sound much smaller than unity but we lay down the basis to extend the code to other dark energy and modified gravity models. We develop the formalism including dark energy non-linearities but, as a first step, we implement the equations in the code after dropping nonlinear self-coupling in the k-essence field. In this simplified setup, we compare k-evolution simulations with those of CLASS and gevolution 1.2, showing the effect of dark matter and gravitational non-linearities on the power spectrum of dark matter, of dark energy and of the gravitational potential. Moreover, we compare k-evolution to Newtonian N -body simulations with back-scaled initial conditions and study how dark energy clustering affects massive halos.

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“…• Modified gravity: Modified gravity N-body codes can be divided into two main categories: Newtonian codes with modified Poisson equation [2302][2303][2304], and relativistic codes [2305][2306][2307]. See Ref.…”

mentioning

confidence: 99%

Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies

Abdalla,

Abellán,

Aboubrahim

et al. 2022

Preprint

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This White Paper has been prepared to fulfill SNOWMASS 2021 requirements and it extends the material previously summarized in the four Letters of Interest [1][2][3][4]. The Particle Physics Community Planning Exercise (a.k.a. SNOWMASS ) is organized by the Division of Particles and Fields of the American Physical Society, and this is an effort to bring together the community of theoretical physicists and cosmologists and identify promising opportunities to address the questions described.This White Paper was initiated with the aim of identifying the opportunities in the cosmological field for the next decade, and strengthening the coordination of the community. It is addressed to identifying the most promising directions of investigation, and rather than attempting a long review of the current status of the whole field of research, it focuses on the upcoming theoretical opportunities and challenges described. The White Paper is a collaborative effort led by Eleonora Di Valentino and Luis Anchordoqui, and it is organized in the topics listed below, each of them coordinated by the scientists indicated (alphabetical order):

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Parametrising non-linear dark energy perturbations

Cited by 21 publications

References 28 publications

Traversable wormholes with vanishing sound speed in f(R) gravity

Traversable wormholes with vanishing sound speed in f(R) gravity

k-evolution: a relativistic N-body code for clustering dark energy

Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies

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