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The apparent accelerating expansion of the Universe is forcing us to examine the foundational aspects of the standard model of cosmology -- in particular, the fact that dark energy is a direct consequence of the homogeneity assumption. We…

宇宙学与河外天体物理 · 物理学 2014-11-21 Chris Clarkson , Roy Maartens

We compute the cosmic microwave background (CMB) anisotropy in a low-density, flat, cosmological constant, cold dark matter model which is normalized to the two-year COBE DMR sky map. Although conclusions regarding model viability must…

天体物理学 · 物理学 2015-06-24 Bharat Ratra , Naoshi Sugiyama

We discuss the thermodynamic and dynamical properties of a variable dark energy model with density scaling as $\rho_x \propto (1+z)^{m}$, z being the redshift. These models lead to the creation/disruption of matter and radiation, which…

宇宙学与河外天体物理 · 物理学 2015-06-04 Philippe Jetzer , Crescenzo Tortora

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.…

宇宙学与河外天体物理 · 物理学 2024-11-05 K. Rezazadeh , A. Ashoorioon , D. Grin

Many models have been studied that contain more than one species of dark matter and some of these couple the Cold Dark Matter (CDM) to a light scalar field. In doing this we introduce additional long range forces, which in turn can…

宇宙学与河外天体物理 · 物理学 2013-10-30 Sophie C. F. Morris , Anne M. Green , Antonio Padilla , Ewan R. M. Tarrant

An interaction between dark matter and dark energy, proportional to the product of their energy densities, results in a scaling behavior of the ratio of these densities with respect to the scale factor of the Robertson-Walker metric. This…

宇宙学与河外天体物理 · 物理学 2017-02-01 R. F. vom Marttens , L. Casarini , W. S. Hipólito-Ricaldi , W. Zimdahl

Imagine a scenario in which the dark energy forms via the condensation of dark matter at some low redshift. The Compton wavelength therefore changes from small to very large at the transition, unlike quintessence or metamorphosis. We study…

天体物理学 · 物理学 2009-11-07 Bruce A. Bassett , Martin Kunz , David Parkinson , Carlo Ungarelli

In this paper we review in detail a number of approaches that have been adopted to try and explain the remarkable observation of our accelerating Universe. In particular we discuss the arguments for and recent progress made towards…

高能物理 - 理论 · 物理学 2008-11-26 Edmund J. Copeland , M. Sami , Shinji Tsujikawa

We investigate cosmologies where the accelerated expansion of the Universe is driven by a field with an anisotropic equation of state. We model such scenarios within the Bianchi I framework, introducing two skewness parameters to quantify…

天体物理学 · 物理学 2009-06-23 Tomi Koivisto , David F. Mota

We describe the observable features of the recently proposed Extended Quintessence scenarios on the Cosmic Microwave Background (CMB) anisotropy spectra. In this class of models a scalar field $\phi$, assumed to provide most of the cosmic…

天体物理学 · 物理学 2016-11-03 Carlo Baccigalupi , Francesca Perrotta , Sabino Matarrese

We present a fully covariant and gauge-invariant calculation of the evolution of anisotropies in the cosmic microwave background (CMB) radiation. We use the physically appealing covariant approach to cosmological perturbations, which…

天体物理学 · 物理学 2008-11-26 Anthony Challinor , Anthony Lasenby

The thermodynamic and dynamical properties of a variable dark energy model with density scaling as rho_x \propto (1+z)^m, z being the redshift, are discussed following the outline of Jetzer et al. This kind of models are proven to lead to…

宇宙学与河外天体物理 · 物理学 2011-09-08 Philippe Jetzer , Crescenzo Tortora

We investigate the consequences of an imperfect dark energy component on the large scale structure. A phenomenological three parameter fluid description is used to study the effect of dark energy on the cosmic microwave background radiation…

天体物理学 · 物理学 2009-11-13 Tomi Koivisto , David F. Mota

In this paper, by analyzing the dynamics of the inhomogeneous quintessence dark energy, we find that the gradient energy of dark energy will oscillate and gradually vanish, which indicates the gradient energy of the scalar field present in…

宇宙学与河外天体物理 · 物理学 2017-05-31 Shuxun Tian , Shuo Cao , Zong-Hong Zhu

Cosmic microwave background (CMB) anisotropies and density fluctuations are calculated for flat cold dark matter (CDM) models with a wide range of parameters, i.e., $\Omega_0, h$ and $\Omega_B$ for both standard recombination and various…

天体物理学 · 物理学 2009-10-22 Naoshi Sugiyama

We consider the distribution of the non-Gaussian signal induced by weak lensing on the primary total intensity cosmic microwave background (CMB) anisotropies. Our study focuses on the three point statistics exploiting an harmonic analysis…

天体物理学 · 物理学 2009-11-10 Fabio Giovi , Carlo Baccigalupi , Francesca Perrotta

We present cosmological perturbation theory in neutrinos probe interacting dark-energy models, and calculate cosmic microwave background anisotropies and matter power spectrum. In these models, the evolution of the mass of neutrinos is…

天体物理学 · 物理学 2009-06-23 Kiyotomo Ichiki , Yong-Yeon Keum

We consider the influence of the dark energy dynamics at the onset of cosmic acceleration on the Cosmic Microwave Background (CMB) bispectrum, through the weak lensing effect induced by structure formation. We study the line of sight…

天体物理学 · 物理学 2009-11-10 F. Giovi , C. Baccigalupi , F. Perrotta

We use the cosmic microwave background temperature anisotropy to place limits on large-scale magnetic fields in an inhomogeneous (perturbed Friedmann) universe. If no assumptions are made about the spacetime geometry, only a weak limit can…

天体物理学 · 物理学 2017-08-23 C. A. Clarkson , A. A. Coley , R. Maartens , C. G. Tsagas