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We investigated a time-varying cosmological constant model using recent BAO measurements from DESI DR2, combined with Type Ia supernova samples (Pantheon$^{+}$, DES-Dovekie, and Union3) and CMB shift parameters, to constrain the…

General Relativity and Quantum Cosmology · Physics 2026-02-17 Himanshu Chaudhary , Ratul Mandal , Masroor Bashir , Vipin Kumar Sharma , Ujjal Debnath

Observational constraints guide one forcefully to examine models in which the matter density is substantially less than critical density. Particularly noteworthy are those which are consistent with inflation. For these models, microwave…

Astrophysics · Physics 2007-05-23 J. P. Ostriker , Paul J. Steinhardt

We study the time evolution of the mutual information between the mass distributions in spatially separated but casually connected regions in an expanding universe. The evolution of the mutual information is primarily determined by the…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-25 Biswajit Pandey

Recent cosmological tensions pose difficulties for $\Lambda$CDM. Forthcoming facilities will be able to check whether these tensions result from systematic effects or indeed with the $\Lambda$CDM model itself. However, these new data will…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-12 Dinko Milaković , John K. Webb

We consider the entropy associated with the large-scale structure of the Universe in the linear regime, where the Universe can be described by a perturbed Friedmann-Lema\^itre spacetime. In particular, we compare two different definitions…

General Relativity and Quantum Cosmology · Physics 2015-09-23 Giovanni Marozzi , Jean-Philippe Uzan , Obinna Umeh , Chris Clarkson

Models of the very early universe, including inflationary models, are argued to produce varying universe domains with different values of fundamental constants and cosmic parameters. Using the cosmological hydrodynamical simulation code…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-10 Luke A. Barnes , Pascal J. Elahi , Jaime Salcido , Richard G. Bower , Geraint F. Lewis , Tom Theuns , Matthieu Schaller , Robert A. Crain , Joop Schaye

The tensions between the values of Hubble constant obtained from the early and the late Universe data pose a significant challenge to modern cosmology. Possible modifications of the flat homogeneous isotropic cosmological {\Lambda}CDM model…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-14 S. L. Parnovsky

This paper offers an original theoretical framework to quantify the information content associated with cosmological structure formation. By taking into account the growth in perturbations for the matter density field, we are able to…

Cosmology and Nongalactic Astrophysics · Physics 2024-08-28 Suman Sarkar

For a universe presently dominated by static or dynamic vacuum energy, cosmological constant (LCDM) or quintessence (QCDM), we calculate the asymptotic collapsed mass fraction as function of the present ratio of vacuum energy to clustered…

Astrophysics · Physics 2016-11-03 Sidney Bludman

The epoch of galaxy formation provides an important additional test of cosmological theories. Cold-dark-matter (CDM) models with cosmological constant ($\Lambda$) are designed to account for the observed excess power in galaxy distribution,…

Astrophysics · Physics 2009-10-28 A. Kashlinsky , R. Jimenez

It is demonstrated that entropy and its density play a significant role in solving the problem of the vacuum energy density (cosmological constant) of the Universe and hence the dark energy problem. Taking this in mind, two most popular…

General Relativity and Quantum Cosmology · Physics 2011-04-07 A. E. Shalyt-Margolin

Recent studies indicate that the configurational entropy is an useful tool to investigate the stability and (or) the relative dominance of states for diverse physical systems. Recent examples comprise the connection between the variation of…

High Energy Physics - Theory · Physics 2017-02-22 Nelson R. F. Braga , Roldao da Rocha

High-precision cosmological observations have revealed persistent tensions within the standard $\Lambda$CDM paradigm, most notably the discrepancy in the Hubble constant and the lower than predicted amplitude of late-time matter clustering…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-28 Biswajit Pandey

We propose a time-varying cosmological constant with a fixed equation of state, which evolves mainly through its interaction with the background during most of the long history of the universe. However, such interaction does not exist in…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-18 Murli Manohar Verma

We revisit a cosmological model where dark matter (DM) and dark energy (DE) follow barotropic equations of state, allowing deviations from the standard $\Lambda$CDM framework (i.e. $w_{dm} \neq 0$, $w_{de} \neq -1$), considering both flat…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-24 Dorian Araya , Cristian Castillo , Genly Leon , Juan Magaña , Angie Barr Domínguez , Miguel A. García-Aspeitia

The distance-redshift relation depends on the amount of matter of each type in the universe. Measurements at different redshifts constrain differing combinations of these matter densities and thus may be used in combination to constrain…

Astrophysics · Physics 2009-08-18 Martin White

The causal entropic principle aims to predict the unexpectedly small value of the cosmological constant Lambda using a weighting by entropy increase on causal diamonds. The original work assumed a purely isotropic and homogeneous cosmology.…

General Relativity and Quantum Cosmology · Physics 2012-01-20 Daniel Phillips , Andreas Albrecht

We consider the process of decay of symmetric vacuum state as evaporation of a Bose condensate of physical Higgs particles, defined over asymmetric vacuum state. Energy density of their selfinteraction is identified with cosmological…

Astrophysics · Physics 2009-11-06 Irina Dymnikova , Maxim Yu. Khlopov

An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant $\Lambda$ should be an approximation, certainly a good one for a fraction of a Hubble time, but it is most likely a temporary…

General Relativity and Quantum Cosmology · Physics 2015-03-19 Joan Sola

A key prediction of cosmological theories for the origin and evolution of structure in the Universe is the existence of a `Doppler peak' in the angular power spectrum of cosmic microwave background (CMB) fluctuations. We present new results…

Astrophysics · Physics 2020-11-25 S. Hancock , G. Rocha , A. N. Lasenby , C. M. Gutierrez