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Reconstructed from lensing tomography, the evolution of the dark matter density field in the well-understood linear regime can provide model-independent constraints on the growth function of structure and the evolution of the dark energy…

Astrophysics · Physics 2008-11-26 Wayne Hu

In order to explain the current acceleration of the Universe, the fine tuning problem of the cosmological constant $\Lambda$ and the cosmic coincidence problem, different alternative models have been proposed in the literature. We use the…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-13 Alexander Bonilla Rivera , Jorge García Farieta

We present a formalism to calculate the non-linear matter power spectrum in modified gravity models that explain the late-time acceleration of the Universe without dark energy. Any successful modified gravity models should contain a…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-03 Kazuya Koyama , Atsushi Taruya , Takashi Hiramatsu

Dark energy (DE) models with many free parameters are often considered excessive, as constraining all parameters poses a significant challenge. While such models offer greater flexibility to probe the DE sector in more detail. With the…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-25 Hanyu Cheng , Supriya Pan , Eleonora Di Valentino

We derive multiple constraints on dark energy and compare dynamical dark energy models with a time-varying equation of state ($w_0 w_a$CDM) versus a cosmological constant model ($\Lambda$CDM). We use Baryon Acoustic Oscillation (BAO) from…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-24 Mustapha Ishak , Leonel Medina-Varela

Within the framework of modified gravity model namely Slotheon model, inspired by the theory of extra dimensions, we explore the behaviour of Dark Energy and the perturbations thereof. The Dark Energy and matter perturbations equations are…

General Relativity and Quantum Cosmology · Physics 2020-07-15 Upala Mukhopadhyay , Debasish Majumdar , Debabrata Adak

In this paper, we combine the latest observational data, including the WMAP five-year data (WMAP5), BOOMERanG, CBI, VSA, ACBAR, as well as the Baryon Acoustic Oscillations (BAO) and Type Ia Supernoave (SN) "Union" compilation (307 sample)…

Astrophysics · Physics 2008-11-26 Jun-Qing Xia , Hong Li , Gong-Bo Zhao , Xinmin Zhang

Nonlinear ordinary differential equations (ODEs) are powerful tools for modeling real-world dynamical systems. However, propagating initial state uncertainty through nonlinear dynamics, especially when the ODE is unknown and learned from…

Systems and Control · Electrical Eng. & Systems 2026-02-06 Peter Amorese , Morteza Lahijanian

Interpreting observations of the Lyman-$\alpha$ forest flux power spectrum requires interpolation between a small number of expensive simulations. We present a Gaussian process emulator modelling the 1D flux power spectrum as a function of…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-17 Christian Pedersen , Andreu Font-Ribera , Keir K. Rogers , Patrick McDonald , Hiranya V. Peiris , Andrew Pontzen , Anže Slosar

We present a Neural Network based emulator for the galaxy redshift-space power spectrum that enables several orders of magnitude acceleration in the galaxy clustering parameter inference, while preserving 3$\sigma$ accuracy better than…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-03 Svyatoslav Trusov , Pauline Zarrouk , Shaun Cole

The present work is based upon a parametric reconstruction of the effective or total equation of state in a model for the universe with accelerated expansion. The constraints on the model parameters are obtained by maximum likelihood…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-27 Ankan Mukherjee

In this work we introduce a new set of parameters $(r_{g}, s_{g})$ involving the linear growth of matter perturbation that can distinguish and constrain different dark energy models very efficiently. Interestingly, for $\Lambda$CDM model…

Cosmology and Nongalactic Astrophysics · Physics 2013-12-24 Sampurnanand , Anjan A. Sen

A nonlinear extension of Schr\"odinger's wave equation is proposed that ensures non-signaling by keeping linear the evolution of \textit{coordinate-diagonal} elements of the density matrix. The equation contains a negative kinetic energy…

Quantum Physics · Physics 2024-03-04 Tamás Geszti

In future power systems, the detailed structure and dynamics may not always be fully known. This is due to an increasing number of distributed energy resources, such as photovoltaic generators, battery storage systems, heat pumps and…

Systems and Control · Electrical Eng. & Systems 2024-11-14 Hannes M. H. Wolf , Christian A. Hans

We provide a model-independent reconstruction of dark energy from $z=0$ to $ \gtrsim 10^5$. We parameterise the model by a perfect fluid with a series of physically well-motivated bins in energy-density, such that the equation of state is…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-01 Adam Moss , Edmund Copeland , Steven Bamford , Thomas Clarke

We study the problem of estimating the coefficients in linear ordinary differential equations (ODE's) with a diverging number of variables when the solutions are observed with noise. The solution trajectories are first smoothed with local…

Statistics Theory · Mathematics 2008-04-29 Heng Lian

We explore an extension of the $\Lambda$CDM model in which the pressure $p$ of the dark energy (DE) fluid evolves with the expansion of the Universe, expressed as a function of the scale factor $a$. The corresponding energy density $\rho$…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-22 Hanyu Cheng , Eleonora Di Valentino , Luis A. Escamilla , Anjan A. Sen , Luca Visinelli

We investigate dynamical behavior of the equation of state of dark energy $w_{de}$ by employing the linear-spline method in the region of low redshifts from observational data (SnIa, BAO, CMB and 12 $H(z)$ data). The redshift is binned and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Rong-Gen Cai , Qiping Su , Hong-Bo Zhang

Abandoning the perfect fluid hypothesis, we investigate here the possibility that the dark energy equation of state (EoS) $w$ is a nonlinear function of the energy density $\rho$. To this aim, we consider four different EoS describing…

Astrophysics · Physics 2009-11-13 V. F. Cardone , C. Tortora , A. Troisi , S. Capozziello

The Lyman-$\alpha$ forest offers a unique avenue for studying the distribution of matter in the high redshift universe and extracting precise constraints on the nature of dark matter, neutrino masses, and other $\Lambda$CDM extensions.…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-29 Laura Cabayol-Garcia , Jonás Chaves-Montero , Andreu Font-Ribera , Christian Pedersen