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In this work, we study a cosmological model of spatially homogeneous and isotropic accelerating universe which exhibits a transition from deceleration to acceleration. For this, Friedmann Robertson Walker(FRW) metric is taken and Hybrid…

General Relativity and Quantum Cosmology · Physics 2021-08-02 G. K. Goswami , Anirudh Pradhan , Meena Mishra , A. Beesham

Determination of the expansion and acceleration history of the universe is one of the fundamental goals of cosmology. Detailed measurements of these rates as a function of redshift can provide new physical insights into the nature and…

Astrophysics · Physics 2009-11-07 Ruth A. Daly , S. G. Djorgovski

Observations of redshift-space distortions in spectroscopic galaxy surveys offer an attractive method for observing the build-up of cosmological structure. In this paper we develop and test a new statistic based on anisotropies in the…

Astrophysics · Physics 2009-11-13 Will J Percival , Martin White

We explore transformations of the Friedman-Lema\^itre-Robertson-Walker (FLRW) metric and cosmological parameters that align with observational data, aiming to gain insights into potential extensions of standard cosmological models. We…

We show that detailed exploration of the $1<z<2$ redshift region can provide for definitive testing not only of the standard inflationary cosmological paradigm with its fine-tuned cosmological constant and its mysteriously late ($z<1$)…

Astrophysics · Physics 2009-11-07 Philip D. Mannheim

In this work we present the first results from a new ray-tracing tool to calculate cosmological distances in the context of fully nonlinear general relativity. We use this tool to study the ability of the general cosmographic representation…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-15 Hayley J. Macpherson

Assuming that the cosmological principle holds, Maartens, Ellis and Stoeger (MES) recently constructed a detailed scheme linking anisotropies in the cosmic background radiation (CMB) with anisotropies and inhomogeneities in the large scale…

Astrophysics · Physics 2008-12-01 William Stoeger , Marcelo Araujo , Tim Gebbie

We use three samples (3CRR, 6CE and 6C*) selected at low radio frequency to constrain the cosmic evolution in the radio luminosity function (RLF) for the `most luminous' steep-spectrum radio sources. Although intrinsically rare, such…

In this work, we explore the phenomenon of cosmic evolution using curved FLRW space-time bounded by apparent horizon with a specific holographic cut-off. To this end, we use the framework of Rastall gravity (RG) and universe is assumed to…

General Relativity and Quantum Cosmology · Physics 2021-05-14 Rabia Saleem , Shahnila

One possibility for explaining the apparent accelerating expansion of the universe is that we live in the center of a spherically inhomogeneous universe. Although current observations cannot fully distinguish $\Lambda$CDM and these…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Kent Yagi , Atsushi Nishizawa , Chul-Moon Yoo

We have considered a spatially flat, homogeneous and isotropic FLRW Universe filled with a single fluid, known as logotropic dark fluid (LDF), whose pressure evolves through a logarithmic equation of state. We use the recent Pantheon SNIa…

General Relativity and Quantum Cosmology · Physics 2021-01-15 Abdulla Al Mamon , Subhajit Saha

We present the time drift of the cosmological redshift in a general spherically symmetric spacetime. We demonstrate that its observation would allow us to test the Copernican principle and so determine if our universe is radially…

Astrophysics · Physics 2009-06-23 Jean-Philippe Uzan , Chris Clarkson , George F. R. Ellis

We present a unified dynamical systems framework for spatially flat FLRW cosmology in $f(Q)$ gravity, covering all three connection branches via a single set of Hubble-normalised variables without fixing $f(Q)$ \textit{a priori}. This…

General Relativity and Quantum Cosmology · Physics 2025-12-17 Jibitesh Dutta , Wompherdeiki Khyllep , Saikat Chakraborty , Daniele Gregoris , Khamphee Karwan

The Einstein Telescope and other third generation interferometric detectors of gravitational waves are projected to be operational post $2030$. The cosmological signatures of gravitational waves would undoubtedly shed light on any departure…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-27 Ayan Mitra , Jurgen Mifsud , David F. Mota , David Parkinson

The assumption of a Friedmann-Lema\^itre-Roberton-Walker (FLRW) Universe is one of the fundamental pillars of modern Cosmology. It is crucial to confront it against cosmological observations in order to confirm (or rule out) the validity of…

General Relativity and Quantum Cosmology · Physics 2022-02-16 Carlos Bengaly

We present results from end-to-end simulations of observations designed to constrain the rate of change in the expansion history of the Universe using the redshift drift of the Lyman-$\alpha$ forest absorption lines along the lines-of-sight…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-19 Chenxing Dong , Anthony Gonzalez , Stephen Eikenberry , Sarik Jeram , Manunya Likamonsavad , Jochen Liske , Deno Stelter , Amanda Townsend

The $\Lambda$CDM cosmological model faces increasingly significant and robust tensions among independent cosmological probes, prompting renewed scrutiny of its foundational assumptions. While General Relativity and the nature of dark energy…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-08 S. M. Koksbang , A. Heinesen

The isotropy of the Lyman-alpha forest in real-space uniquely provides a measurement of cosmic geometry at z > 2. The angular diameter distance for which the correlation function along the line of sight and in the transverse direction agree…

This paper aims to put constraints on the transition redshift $z_t$, which determines the onset of cosmic acceleration, in cosmological-model independent frameworks. In order to perform our analyses, we consider a flat universe and {assume}…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-31 J. F. Jesus , R. F. L. Holanda , S. H. Pereira

We study flat Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) models with a perfect fluid matter source and a scalar field minimally coupled to matter with power-law-exponential \textquotedblleft hybrid\textquotedblright potential. Using…

General Relativity and Quantum Cosmology · Physics 2026-04-20 Koralia Tzanni , John Miritzis