Departures from the Friedmann-Lemaitre-Robertston-Walker Cosmological Model in an Inhomogeneous Universe: A Numerical Examination

Giblin, John T.; Mertens, James B.; Starkman, Glenn D.

doi:10.1103/physrevlett.116.251301

Cited by 92 publications

(113 citation statements)

References 31 publications

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“…Recently, there has been a growing interest in quantifying the importance of effects that are both nonlinear and relativistic on the large scale evolution and development of structure in the Universe [1][2][3][4][5][6][7][8][9]. This means studying effects that may be missed by the standard tool for studying cosmological structure formation: Newtonian N -body simulations.…”

Section: Introductionmentioning

confidence: 99%

Einstein-Vlasov calculations of structure formation

2019

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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 quantities defined with respect to fiducial observers in order to bound relativistic effects. We focus on simplified initial conditions containing a limited range of length scales, but vary the inhomogeneities from small magnitude, where the Newtonian and GR calculations agree quite well, to large magnitude, where the background metric receives an order one correction. For large inhomogeneities, we find that the collapse of overdensities tends to happen faster in Newtonian calculations relative to fully general-relativistic ones. Even in this extreme regime, the differences in the spacetime evolution outside the regions of large gravitational potential and velocity are small. For standard cosmological values, we corroborate the robustness of Newtonian N -body simulations to model large scale perturbations and the related cosmic variance in the local expansion rate.

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Section: Introductionmentioning

confidence: 99%

Einstein-Vlasov calculations of structure formation

2019

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“…Obviously, Eqs (44) and (48) are written according to the properties of the various local and integral terms. Hereafter for simplicity we will compress all these equations by writing…”

Section: I(1)mentioning

confidence: 99%

“…been studied in [38][39][40][41][42], and full numerical relativity simulations have been developed in [43][44][45].…”

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confidence: 99%

Relativistic wide-angle galaxy bispectrum on the light cone

et al. 2018

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Given the important role that the galaxy bispectrum has recently acquired in cosmology and the scale and precision of forthcoming galaxy clustering observations, it is timely to derive the full expression of the large-scale bispectrum going beyond approximated treatments which neglect integrated terms or higher-order bias terms or use the Limber approximation. On cosmological scales, relativistic effects that arise from observing the past light cone alter the observed galaxy number counts, therefore leaving their imprints on N-point correlators at all orders. In this paper we compute for the first time the bispectrum including all general relativistic, local and integrated, effects at second order, the tracers' bias at second order, geometric effects as well as the primordial non-Gaussianity contribution. This is timely considering that future surveys will probe scales comparable to the horizon where approximations widely used currently may not hold; neglecting these effects may introduce biases in estimation of cosmological parameters as well as primordial non-Gaussianity.

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“…Applying nonlinear gravity to cosmological scenarios is a recent advancement in high resolution and accurate numerical simulations. The formalisms employed to do full numerical relativity [5][6][7][8][9][10] have been recently applied to late universe scenarios [11][12][13][14][15][16][17][18][19][20][21] as well as preinflationary scenarios [22][23][24][25] and oscillons [26]. Other work along these lines include adding gravitational effects for scalar metric perturbations, beyond linear order, [27,28] during the preheating period.…”

Section: Introductionmentioning

confidence: 99%

Preheating in full general relativity

Giblin

Tishue

2019

Phys. Rev. D

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We investigate the importance of local gravity during preheating, the nonlinear dynamics that may be responsible for starting the process of reheating the Universe after inflation. We introduce three numerical methods that study a simple preheating scenario while relaxing gravitational assumptions, culminating in studying the process in full numerical relativity. We confirm that perturbation theory is no longer valid when one considers modes whose wavelengths are comparable to the size of the horizon at the end of inflation; however, this breakdown does not necessarily lead to a breakdown of the preheating process in nonlinear gravity. For the specific model we test we find no evidence for the creation of primordial black holes from the instabilities in this model. Finally, we remark on the opportunity for future numerical study of nonlinear gravitational dynamics in the early Universe.

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Departures from the Friedmann-Lemaitre-Robertston-Walker Cosmological Model in an Inhomogeneous Universe: A Numerical Examination

Cited by 92 publications

References 31 publications

Einstein-Vlasov calculations of structure formation

Einstein-Vlasov calculations of structure formation

Relativistic wide-angle galaxy bispectrum on the light cone

Preheating in full general relativity

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