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In this work, two different models, one with cosmological constant $\Lambda$, and baryonic and dark matter (with $\omega_{dm} \neq 0$), and the other with an $X$ dark energy (with $\omega_{de} \neq -1$), and baryonic and dark matter (with…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-05 Emilio Elizalde , Janusz Gluza , Martiros Khurshudyan

Gravitational positivity bounds provide consistency conditions for effective field theories with gravity. They turn out to be phenomenologically useful by providing lower bounds in parameters of new physics beyond the Standard Models (BSM).…

High Energy Physics - Phenomenology · Physics 2025-01-24 Suro Kim , Pyungwon Ko

Geometrothermodynamics is a geometric theory which combines thermodynamics with contact and Riemannian geometry. In this work we use the formalism of geometrothermodynamics to infer cosmological models which predict the observed speed up.…

General Relativity and Quantum Cosmology · Physics 2025-11-12 Alessandro Bravetti , Orlando Luongo

We study constraints that anticipated DEEP survey galaxy counts versus redshift data will place on cosmological model parameters in models with and without a constant or time-variable cosmological constant $\Lambda$. This data will result…

Astrophysics · Physics 2011-07-19 Silviu Podariu , Bharat Ratra

Promptly after high-resolution experiments harbinger the field of precision cosmology low- and high-redshift observations abruptly gave rise to a tension in the measurement of the present-day expansion rate of the Universe ($H_0$) and the…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-08 Luis A. Anchordoqui , Ignatios Antoniadis , Dieter Lust , Neena T. Noble , Jorge F. Soriano

Planck data provide precise constraints on cosmological parameters when assuming the base $\Lambda$CDM model, including a $0.17\%$ measurement of the age of the Universe, $t_0=13.797 \pm 0.023\,{\rm Gyr}$. However, the persistence of the…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-28 Michael Boylan-Kolchin , Daniel R. Weisz

Even though the Dark Energy Spectroscopic Instrument (DESI) mission does not exclude a dynamical dark energy evolution, the concordance paradigm, i.e., the $\Lambda$CDM model, remains statistically favored, as it depends on the fewest…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-08 Anna Chiara Alfano , Orlando Luongo , Marco Muccino

We derive exact theoretical value of the constant cosmic background radiation (CBR) temperature $T_0$ using the interconnections between the Gamow, Alpher and Herman (GAH) hot Big Bang cosmology model of the expanding Universe and the…

General Physics · Physics 2010-12-06 Asger G. Gasanalizade

We explore the implications of finite-temperature quantum field theory effects on cosmological parameters within the framework of the $\L$CDM model and its modification. By incorporating temperature-dependent corrections to the cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-18 I. Y. Park , P. Y. Wui

In this investigation, we perform an observational statistical analysis in the theory of $ f(R, L_m) $ gravity. The proposed theoretical model is based on the Ricci scalar's non-linear contribution. We use a distinct parameterization for…

General Relativity and Quantum Cosmology · Physics 2024-08-30 J. K. Singh , Shaily , Akanksha Singh , Harshna Balhara , Joao R. L. Santos

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

One of the main science goals of the Large Synoptic Survey Telescope (LSST) is to uncover the nature of cosmic acceleration. In the base analysis, possible deviations from the Lambda-Cold-Dark-Matter ($\Lambda$CDM) background evolution will…

In this note, we explore the thermodynamic properties of the universe in the background of the generalized energy-momentum-squared gravity. We derive the energy density of matter from the non-standard continuity equation and use it in our…

General Relativity and Quantum Cosmology · Physics 2021-06-23 Prabir Rudra , Behnam Pourhassan

(Abridged) Fundamental tensions between observations and dark-matter based cosmological models have emerged. This updated review has two purposes: to explore new tensions that have arisen in recent years, compounding the unresolved tensions…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-27 Pavel Kroupa , Eda Gjergo , Elena Asencio , Moritz Haslbauer , Jan Pflamm-Altenburg , Nils Wittenburg , Nick Samaras , Ingo Thies , Wolfgang Oehm

We present improved constraints on an interacting vacuum model using updated astronomical observations including the first data release from Planck. We consider a model with one dimensionless parameter, $\alpha$, describing the interaction…

Cosmology and Nongalactic Astrophysics · Physics 2014-07-09 Yuting Wang , David Wands , Gong-Bo Zhao , Lixin Xu

The large-scale dynamics of the universe is generally described in terms of the time-dependent scale factor $a(t)$. To make contact with observational data, the $a(t)$ function needs to be related to the observable $z(r)$ function, redshift…

General Physics · Physics 2025-06-17 Jan Stenflo

The dark energy in the Universe is described in the context of modified Friedmann equations as a fluid parameterized by the density of dark matter and undergoing an adiabatic expansion. This formulation is applied to the Cardassian model.…

Astrophysics · Physics 2009-11-10 Tomi Koivisto , Hannu Kurki-Suonio , Finn Ravndal

This paper continues the building of the cosmological theory that was introduced in two earlier papers under the title A Dust Universe Solution to the Dark Energy Problem. The model introduced in this theory has existence before time zero…

General Physics · Physics 2010-02-21 James G. Gilson

We extend and apply a model-independent analysis method developed earlier by Daly & Djorgovski to new samples of supernova standard candles, radio galaxy and cluster standard rulers, and use it to constrain physical properties of the dark…

The considerable difference between early and late universe measurements of the Hubble constant, called the Hubble tension, poses a potential challenge to the standard $\Lambda$CDM cosmological model. We examine an interacting dark…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-11 Yismaw Wassie Ambelu , Amare Abebe , Solomon Belay Tessema , Shambel Sahlu