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The conceptual difficulties associated with a cosmological constant have led to the investigation of alternative models in which the equation of state parameter, $w=p/\rho$, of the dark energy evolves with time. We show that combining the…

Astrophysics · Physics 2007-05-23 H. K. Jassal , J. S. Bagla , T. Padmanabhan

I briefly review our current understanding of dark matter and dark energy. The first part of this paper focusses on issues pertaining to dark matter including observational evidence for its existence, current constraints and the `abundance…

Astrophysics · Physics 2022-07-19 Varun Sahni

We test the models of vacuum energy interacting with cold dark matter and try to probe the possible deviation from the $\Lambda$CDM model using current observations. We focus on two specific models, $Q=3\beta H\rho_{\Lambda}$ and $Q=3\beta…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-15 Yun-He Li , Jing-Fei Zhang , Xin Zhang

Dynamical models for dark energy are an alternative to the cosmological constant. It is important to investigate properties of perturbations in these models and go beyond the smooth FRLW cosmology. This allows us to distinguish different…

Cosmology and Nongalactic Astrophysics · Physics 2019-12-04 Manvendra Pratap Rajvanshi , J. S. Bagla

We investigate phenomenological interactions between dark matter and dark energy and constrain these models by employing the most recent cosmological data including the cosmic microwave background radiation anisotropies from Planck 2015,…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-25 André A. Costa , Xiao-Dong Xu , Bin Wang , E. Abdalla

We investigate a phenomenological non-gravitational coupling between dark energy and dark matter, where the interaction in the dark sector is parameterized as an energy transfer either from dark matter to dark energy or the opposite. The…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-11 Riccardo Murgia , Stefano Gariazzo , Nicolao Fornengo

We investigated the influence of \(\kappa\) Minkowski-type quantum spacetime on neutrino oscillations, revealing that spacetime fluctuations introduce a unique energy-dependent power law, \(E^{-4}\), in the decoherence effect for relic…

High Energy Physics - Phenomenology · Physics 2025-03-05 Partha Nandi , Tiasha Bhattacharyya

We make a comparison for ten typical, popular dark energy models according to their capabilities of fitting the current observational data. The observational data we use in this work include the JLA sample of type Ia supernovae observation,…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-08 Yue-Yao Xu , Xin Zhang

In this paper, we test the dark matter-dark energy interacting cosmological model with a dynamic equation of state $w_{DE}(z)=w_{0}+w_{1}z/(1+z)$, using type Ia supernovae (SNe Ia), Hubble parameter data, baryonic acoustic oscillation (BAO)…

Cosmology and Nongalactic Astrophysics · Physics 2015-04-16 J. S. Wang , F. Y. Wang

The concept of dark energy can be used as a possible option to prevent the gravitational collapse of compact objects into singularities. It affects the universe on the largest scale, as it is responsible for our universe's accelerated…

General Relativity and Quantum Cosmology · Physics 2023-08-15 Pramit Rej , Akashdip Karmakar

Current cosmological observations show a strong signature of the existence of a dark energy component with negative pressure. The most obvious candidate for this dark energy is the cosmological constant (with the equation of state…

Astrophysics · Physics 2008-11-26 T. Padmanabhan , T. Roy Choudhury

Since the discovery of the accelerated expansion of the Universe, the constraints on the equation of state $w_\text{DE}$ of dark energy, the stress-energy component responsible for the acceleration, have tightened significantly. These…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-09 Fabian Schmidt

Cosmological dark energy is a natural source of variation of the fine structure constant. Using a model-independent approach we show that once general assumptions about the alpha-varying interactions are made, astronomical probes of its…

Astrophysics · Physics 2015-06-24 David Parkinson , Bruce A. Bassett , John D. Barrow

To explain the currently observed accelerated expansion of the universe, a large number of different theoretical models are presently being discussed. In one way or another, all of these contain `new physics', though at different levels.…

Astrophysics · Physics 2015-06-24 Christian Beck

Dark energy and dark matter constitute 95% of the observable Universe. Yet the physical nature of these two phenomena remains a mystery. Einstein suggested a long-forgotten solution: gravitationally repulsive negative masses, which drive…

General Physics · Physics 2018-12-05 J. S. Farnes

The first and second year results of DESI provide consistent evidence that dark energy may not be quantum vacuum energy ($\Lambda$). If true, this would be an extraordinary development in the 25-year quest to understand cosmic acceleration.…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-17 Matilde L. Abreu , Michael S. Turner

In this work, we propose a new dark energy model by applying the Barrow entropy and the holographic principle, with a time scale as IR cut off. Analysing the conformal time as well as universe's age as infrared cut-offs, we explore the…

General Relativity and Quantum Cosmology · Physics 2020-12-29 Umesh Kumar Sharma , Gunjan Varshney , Vipin Chandra Dubey

It was recently understood that if the swampland conjectures are confronted to experiment they naturally point to a solution of the cosmological hierarchy problem in which the smallness of the dark energy is ascribed to an internal (dark)…

High Energy Physics - Phenomenology · Physics 2023-05-10 Luis A. Anchordoqui , Ignatios Antoniadis , Dieter Lust

The consideration of dark energy's quanta, required also by thermodynamics, introduces its chemical potential into the cosmological equations. Isolating its main contribution, we obtain solutions with dark energy decaying to matter or…

Astrophysics · Physics 2007-05-23 J. Besprosvany

Dark energy is one of the greatest scientific mysteries of today. The idea that dark energy originates from quantum vacuum fluctuations has circulated since the late '60s, but theoretical estimations of vacuum energy have disagreed with the…

General Relativity and Quantum Cosmology · Physics 2021-09-10 Dror Berechya , Ulf Leonhardt