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In cosmology, the cosmic curvature $K$ and the cosmological constant $\Lambda$ are two important parameters, and the values have strong influence on the behavior of the universe. In the context of normal cosmology, under the ordinary…

广义相对论与量子宇宙学 · 物理学 2017-08-11 Ying-Qiu Gu

A data-driven approach to elucidating the nature of the dark energy, in the form of a joint analysis of a full set of cosmological parameters, utilizing all available observational data is proposed. A parameterization of a generalized dark…

天体物理学 · 物理学 2007-05-23 Greg Huey

Is the universe finite or infinite, and what shape does it have? These fundamental questions, of which relatively little is known, are typically studied within the context of the standard model of cosmology where the universe is assumed to…

广义相对论与量子宇宙学 · 物理学 2022-06-02 Gregory J. Galloway , Marcus A. Khuri , Eric Woolgar

The interacting and holographic dark energy models involve two important quantities. One is the characteristic size of the holographic bound and the other is the coupling term of the interaction between dark energy and dark matter. Rather…

高能物理 - 理论 · 物理学 2008-11-26 Bo Hu , Yi Ling

We show that the assumption of a flat universe induces critically large errors in reconstructing the dark energy equation of state at z>~0.9 even if the true cosmic curvature is very small, O(1%) or less. The spuriously reconstructed w(z)…

天体物理学 · 物理学 2008-11-26 Chris Clarkson , Marina Cortes , Bruce A. Bassett

The dynamics of expansion and large scale structure formation of the Universe are analyzed for models with dark energy in the form of a phantom scalar field which initially mimics a $\Lambda$-term and evolves slowly to the Big Rip…

宇宙学与河外天体物理 · 物理学 2013-05-30 Bohdan Novosyadlyj , Olga Sergijenko , Ruth Durrer , Volodymyr Pelykh

Considered is spherical shell as a model for visible universe and parameters that such model must have to comply with the observable data. The topology of the model requires that motion of all galaxies and light must be confined inside a…

综合物理 · 物理学 2017-08-23 Branislav Vlahovic

In this work, we consider the cosmological constraints on the new agegraphic dark energy (NADE) proposed in arXiv:0708.0884, by using the observational data of type Ia supernovae (SNIa), the shift parameter from cosmic microwave background…

天体物理学 · 物理学 2008-11-26 Hao Wei , Rong-Gen Cai

I point out that an effective upper limit of approximately 20 Gyr (for a Hubble constant of 72 km/s/Mpc) or alternatively on the $H_0$-independent quantity $H_0t_0 < 1.47$, exists on the age of the Universe, essentially independent of the…

天体物理学 · 物理学 2009-11-07 Lawrence M. Krauss

We apply the technique of parameter-splitting to existing cosmological data sets, to check for a generic failure of dark energy models. Given a dark energy parameter, such as the energy density Omega_Lambda or equation of state w, we split…

天体物理学 · 物理学 2008-11-26 Sheng Wang , Lam Hui , Morgan May , Zoltan Haiman

Determining the spatial curvature $\Omega_K$ of the Universe has long been crucial in cosmology. In practice, this effort is often entangled with assumptions of dark energy. A combination of distance ($D_{\rm M}$, $D_{\rm L}$) and expansion…

宇宙学与河外天体物理 · 物理学 2024-12-30 Zhennan Li , Pengjie Zhang

We use WMAP5 and other cosmological data to constrain model parameters in quintessence cosmologies, focusing also on their shift when we allow for non-vanishing neutrino masses. The Ratra-Peebles (RP) and SUGRA potentials are used here, as…

宇宙学与河外天体物理 · 物理学 2010-05-28 G. La Vacca , J. R. Kristiansen

Dark energy (and its simplest model, the Cosmological Constant or $\Lambda$) acts as a repulsive force that opposes gravitational attraction. Assuming galaxies maintain a steady state over extended periods, the estimated upper limit on…

宇宙学与河外天体物理 · 物理学 2024-09-17 David Benisty , David Vasak , Jürgen Struckmeier , Horst Stöcker

The mean matter density within the turnaround radius, which is the boundary that separates a nonexpanding structure from the Hubble flow, was recently proposed as a novel cosmological probe. According to the spherical collapse model, the…

宇宙学与河外天体物理 · 物理学 2023-06-14 Giorgos Korkidis , Vasiliki Pavlidou , Konstantinos Tassis

The standard cosmological model assumes a homogeneous and isotropic universe as the background spacetime on large scales called the cosmological principle. However, some observations suggest the possibility of an inhomogeneous and…

宇宙学与河外天体物理 · 物理学 2022-07-08 Koki Yamashita , Yue Nan , Yuuki Sugiyama , Kazuhiro Yamamoto

We derive constraints on the parameter space of the unified model of dark energy and dark matter, the Generalized Chaplygin Gas (GCG), from the amplitudes and positions of the first few peaks and first trough of the cosmic microwave…

天体物理学 · 物理学 2008-11-26 T. Barreiro , O. Bertolami , P. Torres

Dark energy might interact with cold dark matter in a direct, nongravitational way. However, the usual interacting dark energy models (with constant $w$) suffer from some catastrophic difficulties. For example, the $Q\propto\rho_{\rm c}$…

宇宙学与河外天体物理 · 物理学 2014-04-28 Yun-He Li , Xin Zhang

Some problems of cosmology: the big bang singularity, the origin of conventional matter, of dark matter and of dark energy may be successfully described and treated in the framework of the Weyl-Dirac theory. This theory, being a minimal…

广义相对论与量子宇宙学 · 物理学 2013-08-07 Mark Israelit

The interacting dark energy model could propose a effective way to avoid the coincidence problem. In this paper, dark energy is taken as a fluid with a constant equation of state parameter $w_x$. In a general gauge, we could obtain two sets…

宇宙学与河外天体物理 · 物理学 2014-04-10 Weiqiang Yang , Lixin Xu

We use the non-linear spherical model in cold dark matter (CDM) cosmologies with dark energy to investigate the effects of dark energy on the growth of structure and the formation of virialised structures. We consider dark energy models…

天体物理学 · 物理学 2010-12-09 Cathy Horellou , Joel Berge
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