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In the realm of thermodynamics of apparent horizon, we construct a dark energy (DE) model from 4-parameter generalized entropy of apparent horizon in a spatially non-flat universe. In particular, considering a non-zero spatial curvature of…

General Relativity and Quantum Cosmology · Physics 2025-04-07 Sergei D. Odintsov , Simone D'Onofrio , Tanmoy Paul

New Early Dark Energy (NEDE) is a component of vacuum energy at the electron volt scale, which decays in a first-order phase transition shortly before recombination [arXiv:1910.10739]. The NEDE component has the potential to resolve the…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-23 Florian Niedermann , Martin S. Sloth

A simple speed-up cosmology model is proposed to account for the dark energy puzzle. We condense contributions from dark energy and curvature term into one effective parameter in order to reduce parameter degeneracies and to find any…

Astrophysics · Physics 2007-10-10 Xin-He Meng , Meng Su , Zheng Wang

Recent analyses in the literature suggest that the concordance $\Lambda$CDM model with rigid cosmological term, $\Lambda=$const., may not be the best description of the cosmic acceleration. The class of "running vacuum models", in which…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-29 Joan Sola , Adria Gomez-Valent , Javier de Cruz Perez

This paper introduces a novel cosmological model aimed at probing the accelerated expansion of the late Universe through a unique parametrization of the deceleration parameter. We aim to constrain key cosmic parameters by integrating recent…

General Relativity and Quantum Cosmology · Physics 2024-08-14 Himanshu Chaudhary , Ujjal Debnath , G. Mustafa , S. K. Maurya , Farruh Atamurotov

We investigate the constraints on early dark energy (EDE) by combining the most recent CMB observations available, ACT DR4, SPT-3G, and Planck2018 ($\ell_\text{TT,max}=1000$) data. This combined CMB dataset favors non-zero EDE fractions and…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-25 Jun-Qian Jiang , Yun-Song Piao

Minimal dark energy models, described by the same number of free parameters of the standard cosmological model with cold dark matter plus a cosmological constant to parameterize the dark energy component, constitute very appealing scenarios…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-25 Eleonora Di Valentino , Stefano Gariazzo , Carlo Giunti , Olga Mena , Supriya Pan , Weiqiang Yang

Using various latest cosmological datasets including Type-Ia supernovae, cosmic microwave background radiation, baryon acoustic oscillations, and estimations of the Hubble parameter, we test some dark energy models with parameterized…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-28 Jing Yang , Xin-Yan Fan , Chao-Jun Feng , Xiang-Hua Zhai

The Hubble constant estimated from the CMB measurements shows large disagreement with the locally measured value. This inconsistency is called the Hubble tension and is vastly studied in recent years. Early Dark Energy (EDE) gives a few…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-13 Kentaro Kojima , Yuri Okubo

Consistent observations indicate that some of the important cosmological parameters measured through the local observations are in huge tension with their measurements from the global observations (within the minimal $\Lambda$CDM…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-22 Supriya Pan , Weiqiang Yang , Eleonora Di Valentino , Arman Shafieloo , Subenoy Chakraborty

The standard cosmological model currently in force, aka $\Lambda$CDM, has been plagued with a variety of tensions in the last decade or so, which puts it against the wall. At the core of the $\Lambda$CDM we have a rigid cosmological term,…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-19 Adria Gómez-Valent , Joan Solà Peracaula

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 introduce a holographic dark energy model that incorporates the first-order approximate Kaniadaski entropy, utilizing the Hubble horizon, $1/H$, as the infrared cutoff. We investigate the cosmological evolution within this framework. The…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-14 Wei Fang , Guo Chen , Chao-Jun Feng , Wei Du , Chenggang Shu

The standard cosmological model is in the midst of a stress test, thanks to the tension between supernovae-based measurements of the Hubble constant $H_{0}$ and inferences of its values from Cosmic Microwave Background (CMB) anisotropies.…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-05 K. Rezazadeh , A. Ashoorioon , D. Grin

The Phenomenologically Emergent Dark Energy model, a dark energy model with the same number of free parameters as the flat $\Lambda$CDM, has been proposed as a working example of a minimal model which can avoid the current cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-15 Weiqiang Yang , Eleonora Di Valentino , Supriya Pan , Olga Mena

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

It has been noted that with the pre-recombination early dark energy (EDE) resolution of Hubble tension, the preference of recent datasets for the evolving dark energy (DE) can be suppressed significantly. In this work, we clarify and…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-21 Hao Wang , Yun-Song Piao

Despite increasingly precise observations and sophisticated theoretical models, the discrepancy between measurements of H0 from the cosmic microwave background or from Baryon Acoustic Oscillations combined with Big-Bang Nucleosynthesis…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-15 S. Paradiso , M. DiMarco , M. Chen , G. McGee , W. J. Percival

In this study, we explore the impact of various combinations of CMB-independent datasets, including the recent DESI BAO measurements, on the equation of state (EoS) of dark energy and other cosmological parameters within the framework of…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-13 Manisg Yadav , Archana Dixit , M. S. Barak , Anirudh Pradhan

In this work we examine the possibility that the dark energy (DE) density, $\rho_{de}$ can be dynamical and appear as a power series expansion of the Hubble rate (and its derivatives), i.e.$\rho_{de}(H,\dot{H},...)$. For the present…

General Relativity and Quantum Cosmology · Physics 2019-07-30 Mehdi Rezaei , Mohammad Malekjani , Joan Sola