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We propose and construct a two-parameter perturbative expansion around a Friedmann-Lema\^{i}tre-Robertson-Walker geometry that can be used to model high-order gravitational effects in the presence of non-linear structure. This framework…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-15 Sophia R. Goldberg , Timothy Clifton , Karim A. Malik

In this work, we extend previous analyses of the structure formation in the $f(\Box^{-1}R)$ model of nonlocal gravity proposed by Deser and Woodard (DW), which reproduces the background expansion of $\Lambda$CDM with no need of a…

Cosmology and Nongalactic Astrophysics · Physics 2017-05-03 Henrik Nersisyan , Adrian Fernandez Cid , Luca Amendola

We discover a linear relation between two sets of galaxy-lensing cross-correlations. This linear relation holds, as long as light follows the geodesic and the metric is Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW). Violation of the…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-08 Hai Yu , Pengjie Zhang , Jiaxin Wang , Ji Yao , Fa-yin Wang

The dark energy dominated warm dark matter (WDM) model is a promising alternative cosmological scenario. We explore large-scale structure formation in this paradigm. We do this in two different ways: with the halo model approach and with…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Aurel Schneider , Robert E. Smith , Andrea V. Maccio , Ben Moore

We construct a compact phase space for flat FLRW spacetimes with standard matter described by a perfect fluid with a barotropic equation of state for general f(R) theories of gravity, subject to certain conditions on the function f. We then…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Mohamed Abdelwahab , Rituparno Goswami , Peter K. S. Dunsby

The origin of the accelerated expansion of the Universe remains an unsolved mystery in Cosmology. In this work we consider a spatially flat Friedmann-Robertson-Walker (FRW) Universe with non-relativistic matter and a single scalar field…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Remya Nair , Sanjay Jhingan , Deepak Jain

We study geodesics in Friedmann-Lema{\^\i}tre-Robertson-Walker (FLRW) cosmological models and give the full set of solutions. For azimuthal geodesics, in a closed universe, we give the angular distance travelled by a test particle moving…

General Relativity and Quantum Cosmology · Physics 2024-11-13 Christian G. Boehmer , Antonio d'Alfonso del Sordo , Betti Hartmann , Linus Elias Münch

In this methodological note we discuss several topics related to interpretation of some basic cosmological principles. We demonstrate that one of the key points is the usage of synchronous reference frames. The Friedmann-Robertson-Walker…

General Relativity and Quantum Cosmology · Physics 2015-11-20 A. V. Toporensky , S. B. Popov

This paper delves into the late-time accelerated expansion of the universe and the evolution of cosmic structures within the context of a specific \( f(R, L_m) \) gravity model, formulated as \( f(R, L_m) = \lambda R + \beta L_m^\alpha +…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-05 Shambel Sahlu , Alnadhief H. A. Alfedeel , Amare Abebe

According to the separate universe conjecture, spherically symmetric sub-regions in an isotropic universe behave like mini-universes with their own cosmological parameters. This is an excellent approximation in both Newtonian and general…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-14 Gábor Rácz , László Dobos , Róbert Beck , István Szapudi , István Csabai

In this paper we consider a spatially flat Friedmann-Robertson-Walker (FRW) cosmological model with cosmological constant, containing a stiff fluid and a classical Dirac field. The proposed cosmological scenario describes the evolution of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Mauricio Cataldo , Luis Chimento

The set-up of the initial conditions in cosmological N-body simulations is usually implemented by rescaling the desired low-redshift linear power spectrum to the required starting redshift consistently with the Newtonian evolution of the…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-18 Matteo Zennaro , Julien Bel , Francisco Villaescusa-Navarro , Carmelita Carbone , Emiliano Sefusatti , Luigi Guzzo

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

We combine model-independent reconstructions of the expansion history from the latest Pantheon supernovae distance modulus compilation and measurements from baryon acoustic oscillation to test some important aspects of the concordance model…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-25 Arman Shafieloo , Benjamin L'Huillier , Alexei A. Starobinsky

Evidence for almost spatial flatness of the Universe has been provided from several observational probes, including the Cosmic Microwave Background (CMB) and Baryon Acoustic Oscillations (BAO) from galaxy clustering data. However, other…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-14 Raul Jimenez , Ali Rida Khalife , Daniel F. Litim , Sabino Matarrese , Benjamin D. Wandelt

We construct an extension of standard flat FLRW cosmology with matter, possessing local D = 1, N = 1 proper-time supersymmetry. The fundamental equation for the resulting mini-superspace models of quantum universes is a Dirac-like analogue…

General Relativity and Quantum Cosmology · Physics 2015-11-24 M. P. Bogers , J. W. van Holten

The matter creation model of Prigogine--G\'eh\'eniau--Gunzig--Nardone is revisited in terms of a redefined creation pressure which does not lead to irreversible adiabatic evolution at constant specific entropy. With the resulting freedom to…

General Relativity and Quantum Cosmology · Physics 2022-09-15 Rossen I. Ivanov , Emil M. Prodanov

We use numerical relativity simulations to describe the spacetime evolution during nonlinear structure formation in $\Lambda$CDM cosmology. Fully nonlinear initial conditions are set at an initial redshift $z\approx 300$, based directly on…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-12 Robyn L. Munoz , Marco Bruni

In the present paper, we are considering a spatially-flat Friedmann-Robertson-Walker cosmological model, fueled with stiff matter and dust, treated as non-interacting ideal fluid sources. By solving the corresponding Friedmann equation with…

General Relativity and Quantum Cosmology · Physics 2017-04-27 Marina-Aura Dariescu , Denisa Andreea Mihu , Ciprian Dariescu

Using numerical methods, we examine the dynamics of nonlinear perturbations in the expanding time direction, under a Gowdy symmetry assumption, of FLRW fluid solutions to the Einstein-Euler equations with a positive cosmological constant…

General Relativity and Quantum Cosmology · Physics 2023-05-23 Florian Beyer , Elliot Marshall , Todd A. Oliynyk