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It is shown that if a small negative cosmological constant is added to quintessence models with equation of state $p=\omega\rho$ on the range $-1 <\omega < -1/3$, the resulting scenarios could not contain any future event horizons.…

Astrophysics · Physics 2007-05-23 Pedro F. Gonzalez-Diaz

Recent observations on the large-scale structure of the universe indicate that the cosmological constant cannot be the definitive answer to the nature of dark energy. Therefore, it is a good time to propose alternatives to understand the…

General Relativity and Quantum Cosmology · Physics 2024-09-12 I. A. Sarmiento Alvarado , Maribel Hernández Márquez , Tonatiuh Matos

In our present work, we study the evolution of the universe by assuming an interacting dark energy model, where dark energy interacts with matter. Basing on this model, first we calculated the dark energy density parameter and using this we…

General Relativity and Quantum Cosmology · Physics 2019-12-30 Debasis Sahu , Bibekananda Nayak

The paper presents the transition of universe from early decelerating phase to current accelerating phase with viscous fluid and time dependent cosmological constant $(\Lambda)$ as source of matter in Bianchi-V space-time. To study the…

General Physics · Physics 2012-07-06 Anil Kumar Yadav

We propose a model universe, in which the dimension of the space is a continuous variable, which can take any real positive number. The dynamics leads to a model in which the universe has no singularity. The difference between our model and…

General Relativity and Quantum Cosmology · Physics 2007-05-23 M. Khorrami , R. Mansouri , M. Mohazzab , M. R. Ejtehadi

Based on the assumption that the dark energy possessing bulk viscosity is homogenously and isotropically permeated in the universe, we propose three new viscous dark energy (VDE) models to characterize the accelerating universe. By…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-30 Deng Wang , Yang-Jie Yan , Xin-He Meng

Recently we proposed a mechanism for sequestering the Standard Model vacuum energy that predicts that the universe will collapse. Here we present a simple mechanism for bringing about this collapse, employing a scalar field whose potential…

High Energy Physics - Theory · Physics 2015-04-03 Nemanja Kaloper , Antonio Padilla

Recent observations confirm that our universe is flat and consists of a dark energy component $\Omega_{DE}\simeq 0.7$. This dark energy is responsible for the cosmic acceleration as well as determines the feature of future evolution of the…

High Energy Physics - Theory · Physics 2007-05-23 Mian Wang

The model where the universe is considered as an expanding spherical 3-brane allows us to explain its expansion rate without a dark energy component. In this scenario the computed redshift that corresponds to the transition from cosmic…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Merab Gogberashvili

A new expression to the total age of the Universe is derived in terms of the average deceleration parameter. This kinematic result holds regardless of the curvature of the universe as well as of the underlying gravity theory. It remains…

Astrophysics · Physics 2008-06-11 J. A. S. Lima

In this paper, a general entropy-corrected FRW cosmological model has been presented in which a deceleration-to-acceleration transition occurs according to recent observations. We found that the case for the flat universe ($k=0$), supported…

General Relativity and Quantum Cosmology · Physics 2019-10-23 Nasr Ahmed , Sultan Z. Alamri

Understanding the accelerating expansion of the Universe remains a fundamental challenge in modern cosmology. In this paper, we investigate a cosmological model parametrized by a generalized variable deceleration parameter to elucidate the…

General Relativity and Quantum Cosmology · Physics 2023-09-29 M. Koussour , N. Myrzakulov , Alnadhief H. A. Alfedeel , F. Awad , M. Bennai

We introduce a new proposal for the onset of cosmic acceleration based on mass-varying neutrinos. When massive neutrinos become nonrelativistic, the $Z_2$ symmetry breaks, and the quintessence potential becomes positive from its initially…

General Relativity and Quantum Cosmology · Physics 2017-06-21 H. Mohseni Sadjadi , V. Anari

Recent observations of Type Ia supernovae provide evidence for the acceleration of our universe, which leads to the possibility that the universe is entering an inflationary epoch. We simulate it under a ``big bounce'' model, which contains…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Beili Wang , Hongya Liu , Lixin Xu

We have observed the acceleration of the expansion of the universe. To explain this phenomenon, we usually introduce the dark energy (DE) which has a negative pressure or we need to modify the Einstein's equation to produce a term which is…

Cosmology and Nongalactic Astrophysics · Physics 2011-11-04 Dong-Biao Kang

The consensus of opinion in cosmology is that the Universe is currently undergoing a period of accelerated expansion. With current and proposed high precision experiments it offers the hope of being able to discriminate between the two…

Astrophysics · Physics 2011-02-09 P. S. Corasaniti , E. J. Copeland

In this work we show that the presence of a vector field on cosmological scales could explain the present phase of accelerated expansion of the universe. The proposed theory contains no dimensional parameters nor potential terms and does…

Astrophysics · Physics 2008-12-18 Jose Beltran Jimenez , Antonio L. Maroto

Current cosmological data indicate that our universe contains a substantial component of dark vacuum energy that is driving the cosmos to accelerate. We examine the immediate and longer term consequences of this dark energy (assumed here to…

Astrophysics · Physics 2010-12-09 Michael T. Busha , Fred C. Adams , Risa H. Wechsler , August E. Evrard

Assuming a cellular structure for the space-time, we propose a model in which the expansion of the universe is understood as a decrumpling process, much like the one we know from polymeric surfaces. The dimension of space is then a…

General Relativity and Quantum Cosmology · Physics 2007-05-23 M. Khorrami , M. Mansouri , M. Mohazzab

In this talk we present a model of the universe in which dark energy is modelled explicitely with both a dynamical quintessence field and a cosmological constant. Our results confirm the possibility of a collapsing universe (for a given…

Astrophysics · Physics 2007-05-23 Rolando Cardenas , Tame Gonzalez , Osmel Martin , Israel Quiros
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