共查询到20条相似文献,搜索用时 31 毫秒
1.
We investigate the influence of an interaction between dark energy and dark matter upon the dynamics of galaxy clusters. We obtain the general Layser–Irvine equation in the presence of interactions, and find how, in that case, the virial theorem stands corrected. Using optical, X-ray and weak lensing data from 33 relaxed galaxy clusters, we put constraints on the strength of the coupling between the dark sectors. Available data suggests that this coupling is small but positive, indicating that dark energy might be decaying into dark matter. Systematic effects between the several mass estimates, however, should be better known, before definitive conclusions on the magnitude and significance of this coupling could be established. 相似文献
2.
Effects of dark energy interacting with massive neutrinos and dark matter on universe evolution 下载免费PDF全文
In this paper we investigate the evolution of the
cosmology model with dark energy interacting with massive neutrinos
and dark matter. Using the numerical method to investigate the
dynamical system, we find that the stronger the interaction between
dark energy and dark matter, the lower the ratio of dark matter
in the universe is; also, the stronger the interaction between dark
energy and massive neutrinos, the lower the ratio of massive
neutrinos in the universe is. On the other hand, the interaction
between dark energy and dark matter or massive neutrinos has an
effect on disturbing the universe's acceleration; we also find that
our universe is still accelerating. 相似文献
3.
In this work we perform some studies related to dark energy. Firstly, we propose a dynamical approach to explain the dark
energy contents of the universe. We assume that a massless scalar field couples to the Hubble parameter with some Planck-mass
suppressed interactions. This scalar field develops a Hubble parameter-dependent (thus time-dependent) vacuum expectation
value, which renders a time-independent relative density for the dark energy and thus can explain the coincidence of the dark
energy density of the universe. Furthermore, we assume that the dark matter particle is metastable and decays very late into
the dark energy scalar field. Such a conversion of matter to dark energy can give an explanation for the starting time of
the accelerating expansion of the universe. Secondly, we introduce multiple Affleck-Dine fields to the landscape scenario
of dark energy in order to have the required baryon-asymmetrical universe.
PACS:
95.36. + x, 95.35. + d 相似文献
4.
Yin-Zhe Ma Yan Gong Xuelei Chen 《The European Physical Journal C - Particles and Fields》2010,69(3-4):509-519
We consider the interaction between dark matter and dark energy in the framework of holographic dark energy, and propose a natural and physically plausible form of interaction, in which the interacting term is proportional to the product of the powers of the dark matter and dark energy densities. We investigate the cosmic evolution in such models. The impact of the coupling on the dark matter and dark energy components may be asymmetric. While the dark energy decouples from the dark matter at late time, just as other components of the cosmic fluid become decoupled as the universe expands, interestingly, the dark matter may actually become coupled to the dark energy at late time. We shall call such a phenomenon incoupling. We use the latest type Ia supernovae data from the SCP team, baryon acoustics oscillation data from SDSS and 2dF surveys, and the position of the first peak of the CMB angular power spectrum to constrain the model. We find that the interaction term which is proportional to the first power product of the dark energy and dark matter densities gives an excellent fit to the current data. 相似文献
5.
Taking the flat rotation curve as input and treating the matter content in the galactic halo region as perfect fluid we obtain a space–time metric at the galactic halo region in the framework of general relativity. We find that the resultant space–time metric is a non-relativistic dark matter induced space–time embedded in a static Friedmann–Lemaître–Robertson–Walker universe i.e. the flat rotation curve not only leads to the existence of dark matter but also suggests about the background geometry of the universe. Within its range of validity the flat rotation curve and the demand that the dark matter to be non-exotic together indicate for a (nearly) flat universe as favored by the modern cosmological observations. We obtain the expressions for energy density and pressure of dark matter there and consequently the equation of state of dark matter. Various other aspects of the solutions are also analyzed. 相似文献
6.
By considering the logarithmic correction to the energy density, we study the behavior of Hubble parameter in the holographic
dark energy model. We assume that the universe is dominated by interacting dark energy and matter and the accelerated expansion
of the universe, which may be occurred in the early universe or late time, is studied. 相似文献
7.
We investigate several varying-mass dark matter particle models in the framework of phantom cosmology. We examine whether there exist late-time cosmological solutions, corresponding to an accelerating universe and possessing dark energy and dark matter densities of the same order. Imposing exponential or power-law potentials and exponential or power-law mass dependence, we conclude that the coincidence problem cannot be solved or even alleviated. Thus, if dark energy is attributed to the phantom paradigm, varying-mass dark matter models cannot fulfill the basic requirement that led to their construction. 相似文献
8.
SUN Cheng-Yi 《理论物理通讯》2011,56(1):193-198
In the paper, we apply the weak gravity conjecture to the holographic quintessence model of dark energy. Three different holographic dark energy models are considered: without the interaction in the non-flat universe; with interaction in the flat universe; with interaction in the non-flat universe. We find that
only in the models with the spatial curvature and interaction term proportional to the energy density of matter, it is possible for the weak gravity conjecture to be satisfied. And it seems that the weak gravity conjecture favors an open universe and the decaying of matter into dark energy. 相似文献
9.
Yousef Bisabr 《General Relativity and Gravitation》2009,41(2):305-313
We study the holographic dark energy model in a generalized scalar tensor theory. In a universe filled with cold dark matter
and dark energy, the effect of potential of the scalar field is investigated in the equation of state parameter. We show that
for a various types of potentials, the equation of state parameter is negative and transition from deceleration to acceleration
expansion of the universe is possible. 相似文献
10.
A cross-correlation technique of lensing tomography is developed to probe dark energy in the Universe. The variation of weak shear with redshift around foreground galaxies depends only on the angular distances and is robust to the dominant systematic error in lensing. We estimate the margin-alized accuracies that deep lensing surveys with photometric redshifts can provide on the dark energy density Omega(de), the equation of state parameter w, and its evolution w('): sigma(w) approximately equal 0.01f(-1/2)(sky) and sigma(w(')) approximately equal 0.03f(-1/2)(sky), where a prior of sigma(Omega(de))=0.03 is assumed in the marginalization. 相似文献
11.
We investigate the possibility that both the baryon asymmetry of the universe and the observed cold dark matter density are generated by decays of a heavy scalar field which dominates the universe before nucleosynthesis. Since baryons and cold dark matter have common origin, this mechanism yields a natural explanation of the similarity of the corresponding energy densities. The cosmological moduli and gravitino problems are avoided. 相似文献
12.
13.
14.
Piyali Bhar Farook Rahaman Tuhina Manna Ayan Banerjee 《The European Physical Journal C - Particles and Fields》2016,76(12):708
In this article, we study the possibility of sustaining static and spherically symmetric traversable wormhole geometries admitting conformal motion in Einstein gravity, which presents a more systematic approach to search a relation between matter and geometry. In wormhole physics, the presence of exotic matter is a fundamental ingredient and we show that this exotic source can be dark energy type which support the existence of wormhole spacetimes. In this work we model a wormhole supported by dark energy which admits conformal motion. We also discuss the possibility of the detection of wormholes in the outer regions of galactic halos by means of gravitational lensing. Studies of the total gravitational energy for the exotic matter inside a static wormhole configuration are also performed. 相似文献
15.
We consider a spatially homogeneous and totally anisotropic Bianchi-I space-time with perfect fluid (dark matter and standard
visible matter) and anisotropic dark energy, which has dynamical energy density. The two sources are assumed to interact minimally
and therefore their energy momentum tensors are conserved separately. Using suitable physical assumptions, the field equations
are solved exactly. Various dark energy models are studied and it is found that quintessence model is suitable for describing
the present evolution of the universe. The geometrical and kinematical features of the models and the behavior of the anisotropy
of the dark energy, are examined in detail. 相似文献
16.
To test modified Newtonian dynamics (MOND) on galactic scales, we study six strong gravitational lensing early-type galaxies from the CASTLES sample. Comparing the total mass (from lensing) with the stellar mass content (from a comparison of photometry and stellar population synthesis), we conclude that strong gravitational lensing on galactic scales requires a significant amount of dark matter, even within MOND. On such scales a 2 eV neutrino cannot explain the excess of matter in contrast with recent claims to explain the lensing data of the bullet cluster. The presence of dark matter is detected in regions with a higher acceleration than the characteristic MOND scale of approximately 10(-10) m/s(2). This is a serious challenge to MOND unless lensing is qualitatively different [possibly to be developed within a covariant, such as Tensor-Vector-Scalar (TeVeS), theory]. 相似文献
17.
Weak gravitational lensing of background galaxies by intervening matter directly probes the mass distribution in the Universe. This distribution is sensitive to both the dark energy and neutrino mass. We examine the potential of lensing experiments to measure features of both simultaneously. Focusing on the radial information contained in a future deep 4000 deg(2) survey, we find that the expected (1-sigma) error on a neutrino mass is 0.1 eV, if the dark-energy parameters are allowed to vary. The constraints on dark-energy parameters are similarly restrictive, with errors on w of 0.09. 相似文献
18.
M. Lubini C. Tortora J. Näf Ph. Jetzer S. Capozziello 《The European Physical Journal C - Particles and Fields》2011,71(12):1834
For a general class of analytic f(R)-gravity theories, we discuss the weak field limit in view of gravitational lensing. Though an additional Yukawa term in
the gravitational potential modifies dynamics with respect to the standard Newtonian limit of General Relativity, the motion
of massless particles results unaffected thanks to suitable cancellations in the post-Newtonian limit. Thus, all the lensing
observables are equal to the ones known from General Relativity. Since f(R)-gravity is claimed, among other things, to be a possible solution to overcome for the need of dark matter in virialized
systems, we discuss the impact of our results on the dynamical and gravitational lensing analyses. In this framework, dynamics
could, in principle, be able to reproduce the astrophysical observations without recurring to dark matter, but in the case
of gravitational lensing we find that dark matter is an unavoidable ingredient. Another important implication is that gravitational
lensing, in the post-Newtonian limit, is not able to constrain these extended theories, since their predictions do not differ
from General Relativity. 相似文献
19.
A general holographic relation between UV and IR cutoff of an effective field theory is proposed. Taking the IR cutoff relevant to the dark energy as the Hubble scale, we find that the cosmological constant is highly suppressed by a numerical factor and the fine tuning problem seems alleviative. We also use different IR cutoffs to study the case in which the universe is composed of matter and dark energy. 相似文献
20.
《Physics letters. [Part B]》2006,632(5-6):597-604
Phantom cosmology allows to account for dynamics and matter content of the universe tracing back the evolution to the inflationary epoch, considering the transition to the non-phantom standard cosmology (radiation/matter dominated eras) and recovering the today observed dark energy epoch. We develop the unified phantom cosmology where the same scalar plays the role of early time (phantom) inflaton and late-time dark energy. The recent transition from decelerating to accelerating phase is described too by the same scalar field. The (dark) matter may be embedded in this scheme, giving the natural solution of the coincidence problem. It is explained how the proposed unified phantom cosmology can be fitted against the observations which opens the way to define all the important parameters of the model. 相似文献