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1.
In this work, I consider the logarithmic-corrected and the power-law corrected versions of the holographic dark energy (HDE) model in the non-flat FRW universe filled with a viscous Dark Energy (DE) interacting with Dark Matter (DM). I propose to replace the infra-red cut-off with the inverse of the Ricci scalar curvature R. I obtain the equation of state (EoS) parameter ω Λ , the deceleration parameter q and the evolution of energy density parameter $\varOmega_{D}'$ in the presence of interaction between DE and DM for both corrections. I study the correspondence of the logarithmic entropy corrected Ricci Dark Dnergy (LECRDE) and power-law entropy corrected Ricci Dark Energy (PLECRDE) models with the the Modified Chaplygin Gas (MCG) and some scalar fields including tachyon, K-essence, dilaton and quintessence. I also make comparisons with previous results.  相似文献   

2.
We provide a new way of constraining the relative scintillation efficiency Leff for liquid xenon. Using a simple estimate for the electronic and nuclear stopping powers together with an analysis of recombination processes we predict both the ionization and the scintillation yields. Using presently available data for the ionization yield, we can use the correlation between these two quantities to constrain Leff from below. Moreover, we argue that more reliable data on the ionization yield would allow to verify our assumptions on the atomic cross sections and to predict the value of Leff. We conclude that the relative scintillation efficiency should not decrease at low nuclear recoil energies, which has important consequences for the robustness of exclusion limits for low WIMP masses in liquid xenon Dark Matter searches.  相似文献   

3.
The recently released Planck data have constrained 4-dimensional inflationary parameters even more accurately than ever. We consider an extension of the braneworld model with induced gravity and a non-minimally coupled scalar field on the brane. We constraint the inflation parameters in this setup, by adopting six types of potential, in confrontation with the joint Planck + WMAP9 + BAO data. We show that a potential of the type V(φ)=V 0exp(?βφ) has the best fit with newly released observational data.  相似文献   

4.
In this work, we study the New Agegraphic Dark Energy (NADE) model (which contains the conformal time η as infrared cut-off) in the framework of Brans-Dicke cosmology with chameleon scalar field which is non-minimally coupled to the matter field. Considering interacting Dark Energy and Dark Matter (DM), we calculate some relevant cosmological parameters, i.e. the equation of state (EoS) parameter, the deceleration parameter q and the evolution of the energy density parameter $\varOmega_{D}'$ for different forms of scale factors, i.e. the power-law, the emergent, the intermediate and the logamediate ones, which leads to different expressions of η.  相似文献   

5.
We propose a model of the evolution of the tachyonic scalar field over two phases in the universe. The field components do not interact in phase I, while in the subsequent phase II, they change flavours due to relative suppression of the radiation contribution. In phase II, we allow them to interact mutually with time-independent perturbation in their equations of state, as Shifted Cosmological Parameter (SCP) and Shifted Dust Matter (SDM). We determine the solutions of their scaling with the cosmic redshift in both phases. We further suggest the normalised Hubble function diagnostic, which, together with the low- and high-redshift H(z) data and the concordance values of the present density parameters from the CMBR, BAO statistics etc., constrain the strength of interaction by imposing the viable conditions to break degeneracy in 3-parameter $(\gamma, \varepsilon, \dot{\phi}^{2})$ space. The range of redshifts (z=0.1 to z=1.75) is chosen to highlight the role of interaction during structure formation, and it may lead to a future analysis of power spectrum in this model vis a vis Warm Dark Matter (WDM) or ΛCDM models. We further calculate the influence of interaction in determining the age of the universe at the present epoch, within the degeneracy space of model parameters.  相似文献   

6.
We have succeeded in establishing a cosmological model with a non-minimally coupled scalar field φ that can account not only for the spatial periodicity or the picket-fence structure exhibited by the galaxy N-z relation of the 2dF survey but also for the spatial power spectrum of the cosmic microwave background radiation (CMB) temperature anisotropy observed by the WMAP satellite. The Hubble diagram of our model also compares well with the observation of Type Ia supernovae. The scalar field of our model universe starts from an extremely small value at around the nucleosynthesis epoch, remains in that state for sufficiently long periods, allowing sufficient time for the CMB temperature anisotropy to form, and then starts to grow in magnitude at the redshift z of ～1, followed by a damping oscillation which is required to reproduce the observed picket-fence structure of the N-z relation. To realize such behavior of the scalar field, we have found it necessary to introduce a new form of potential V(φ)∝ φ 2exp?(?q φ 2), with q being a constant. Through this parameter q, we can control the epoch at which the scalar field starts growing.  相似文献   

7.
Among different candidates to play the role of Dark Energy (DE), modified gravity has emerged as offering a possible unification of Dark Matter (DM) and DE. The purpose of this work is to develop a reconstruction scheme for the modified gravity with f(T) action using holographic energy density. In the framework of the said modified gravity we have considered the equation of state of the Holographic DE (HDE) density. Subsequently we have developed a reconstruction scheme for modified gravity with f(T) action. Finally we have obtained a modified gravity action consistent with the HDE scenario.  相似文献   

8.
A cryogenic search for WIMP Dark Matter with small sapphire bolometers through the WIMP scattering off Al2O3 nuclei, the ROSEBUD (Rare Objects SEarch with Bolometers UndergrounD) experiment, is being installed in the Canfranc Underground Laboratory (Spain) at 2450 m water equivalent. The performances of the bolometers, the radioactive background expected from the measurement of the radiopurity of the ROSEBUD components and the estimated sensitivity of the experiment for low mass WIMP detection are presented.  相似文献   

9.
In this paper, we study the dynamics of warm inflation in which slow-roll inflation is driven by non-Abelian gauge fields. To this end, we use the geometry of locally rotationally symmetric Bianchi type I universe model. We construct dynamical equations, i.e., first model field equation, energy conservation equations and equation of motion under slow-roll approximation. In order to discuss inflationary perturbations, we evaluate parameters like scalar and tensor power spectra as well as scalar and tensor spectral indices. We also evaluate inflaton, directional Hubble parameter, slow-roll and perturbation parameters as well as tensor-scalar ratio as a function of inflaton during intermediate and logamediate inflationary eras. It is concluded that anisotropic inflationary universe model with non-Abelian gauge fields remains compatible with WMAP7.  相似文献   

10.
Annual modulation due to the Earth's motion around the Sun is a well-known signature of the expected weakly interacting massive particle (WIMP) signal induced in a solid state underground detector. In the present paper, we discuss the prospects of this technique on statistical grounds, introducing annual-modulation sensitivity plots for the WIMP–nucleon scalar cross-section for different materials and experimental conditions. The highest sensitivity to modulation is found in the WIMP mass interval 10mW130 GeV, the actual upper limit depends on the choice of the astrophysical parameters, while the lowest values of the explorable WIMP–nucleon elastic cross-sections fall in most cases within one order of magnitude of the sensitivities of the present direct detection WIMP searches.  相似文献   

11.
Motivated by the holographic principle, it has been suggested that the dark energy density may be inversely proportional to the area A of the event horizon of the universe. However, such a model would have a causality problem. In this work, we consider the entropy-corrected version of the holographic dark energy model in the non-flat FRW universe and we propose to replace the future event horizon area with the inverse of the Ricci scalar curvature. We obtain the equation of state (EoS) parameter ω Λ, the deceleration parameter q and WD￠\Omega_{D}' in the presence of interaction between Dark Energy (DE) and Dark Matter (DM). Moreover, we reconstruct the potential and the dynamics of the tachyon, K-essence, dilaton and quintessence scalar field models according to the evolutionary behavior of the interacting entropy-corrected holographic dark energy model.  相似文献   

12.
In this paper, we study the domain wall with time dependent displacement vectors based on Lyra geometry in normal gauge i.e. displacement vector φ i * =[β(t),0,0,0]. The field theoretic energy momentum tensor is considered with zero pressure perpendicular to the wall. We find an exact solutions of Einstein’s equation for a scalar field φ with a potential V(φ) describing the gravitational field of a plane symmetric domain wall. We have seen that the hyper surfaces parallel to the wall (z=constant) are three dimensional de-sitter spaces. It is also shown that the gravitational field experienced by test particle is attractive.  相似文献   

13.
The very early universe must have been extremely homogeneous, even on scales far exceeding the particle horizon. Within the framework of the standard Friedmann cosmology, homogenization can only be achieved by quantum effects which violate classical causality. This could happen when the particle horizon was smaller than the Compton wavelength of the pion. The assumption that statistical departures from equilibrium started to grow after this epoch leads to a prediction of the density fluctuations at recombination. The amplitude ν of the fluctuations should have a maximum of about 0.007 on scales of 81017M. For smaller scales, ν ∝M +1/6, and for larger scales, ν ∝M ?1/2. This suggests that superclusters condense out at a red shift of about 11, and clusters and then galaxies form shortly after by fragmentation.  相似文献   

14.
We show that in the framework of R2 gravity and in the linearized approach it is possible to obtain spherically symmetric stationary states that can be used as a model for galaxies. Such approach could represent a solution to the Dark Matter Problem. In fact, in the model, the Ricci curvature generates a high energy term that can in principle be identified as the dark matter field making up the galaxy. The model can also help to have a better understanding on the theoretical basis of Einstein-Vlasov systems. Specifically, we discuss, in the linearized R2 gravity, the solutions of a Klein-Gordon equation for the spacetime curvature. Such solutions describe high energy scalarons, a field that in the context of galactic dynamics can be interpreted like the no-light-emitting galactic component. That is, these particles can be figured out like wave-packets showing stationary solutions in the Einstein-Vlasov system. In such approximation, the energy of the particles can be thought of as the galactic dark matter component that guarantees the galaxy equilibrium. Thus, because of the high energy of such particles the coupling constant of the R2-term in the gravitational action comes to be very small with respect to the linear term R. In this way, the deviation from standard General Relativity is very weak, and in principle the theory could pass the Solar System tests. As pertinent to the issue under analysis in this paper, we present an analysis on the gravitational lensing phenomena within this framework.Although the main goal of this paper is to give a potential solution to the Dark Matter Problem within galaxies, we add a section where we show that an important property of the Bullet Cluster can in principle be explained in the scenario introduced in this work.To the end, we discuss the generic prospective to give rise to the Dark Matter component of most galaxies within extended gravity.  相似文献   

15.
We examine the effects of NH3 ice particle clouds in the atmosphere of Jupiter on outgoing thermal radiances. The cloud models are characterized by a number density at the cloud base, by the ratio of the scale height of the vertical distribution of particles (Hp) to the gas scale height (Hg), and by an effective particle radius. NH3 ice particle-scattering properties are scaled from laboratory measurements. The number density for the various particle radius and scale height models is inferred from the observed disk average radiance at 246 cm?1, and preliminary lower limits on particle sizes are inferred from the lack of apparent NH3 absorption features in the observed spectral radiances as well as the observed minimum flux near 2100 cm?1. We find lower limits on the particle size of 3 μm if Hp/Hg = 0.15, or 10μmif Hp/Hg = 0.50 or 0.05. NH3 ice particles are relatively dark near the far-infrared and 8.5-μm atmospheric windows, and the outgoing thermal radiances are not very sensitive to various assumptions about the particle-scattering function as opposed to radiances at 5 μm, where particles are relatively brighter. We examined observations in these three different spectral window regions which provide, in principle, complementary constraints on cloud parameters. Characterization of the cloud scale height is difficult, but a promising approach is the examination of radiances and their center-to-limb variation in spectral regions where there is significant opacity provided by gases of known vertical distribution. A blackbody cloud top model can reduce systematic errors due to clouds in temperature sounding to the level of 1K or less. The NH3 clouds provide a substantial influence on the internal infrared flux field near the 600-mbar level.  相似文献   

16.
Based on Das and Banerjee (Phys. Rev D 78:043512, 2008), we assume there is a non-minimal coupling between scalar field and matter in the Brans-Dicke model. We analyzes the motion of different matter such as, massless scalar field, photon, massless perfect fluid (dust), massive perfect fluid and point particle matter in this study. We show that the motion of massless scalar field and photon can satisfy null geodesic motion only in high frequency limit. Also we find that the motion of the dust and massive perfect fluid is geodesic for L m =?P and it is non-geodesic for L m =ρ. Finally, we study the motion of point particle and show that the motion of this kind of matter is like massive perfect fluid.  相似文献   

17.
Evolution of the universe is discussed in the framework of f(R) theory of gravity. The deceleration parameter is used to interpret various phases of the universe. We investigate the future evolution of the flat FRW universe by using observationally viable f(R) models. A numerical technique is applied to solve the evolution equation in terms of Hubble parameter which is used to explore late time acceleration of the universe. Some novel and interesting results based on the choice of coupling parameters in gravitational action are obtained. We can conclude that the considered f(R) models imply unification of matter dominated epoch with present accelerating phase of the universe.  相似文献   

18.
We study the effects of the non-minimal coupling on the dissipative dynamics of the warm inflation in a braneworld setup, where the inflaton field is non-minimally coupled to induced gravity on the warped DGP brane. A warped DGP scenario is a hybrid model containing both DGP and RSII character. We study with details the effects of the non-minimal coupling and dissipation on the inflationary dynamics on the normal DGP branch of this hybrid scenario in the high-dissipation and high-energy regime. We show that incorporation of the non-minimal coupling in this setup decreases the number of e-folds relative to the minimal case. We also compare our model parameters with recent observational data.  相似文献   

19.
The aim of this paper is to study the warm inflation during intermediate era in the framework of locally rotationally symmetric Bianchi type I universe model. We assume that the universe is composed of inflaton and imperfect fluid having radiation and bulk viscous pressure. To this end, dynamical equations (first model field equation and energy conservation equations) under slow-roll approximation and in high dissipative regime are constructed. A necessary condition is developed for the realization of this anisotropic model. We assume both dissipation and bulk viscous coefficients variable as well as constant. We evaluate entropy density, scalar (tensor) power spectra, their corresponding spectral indices, tensor–scalar ratio and running of spectral index in terms of inflaton. These cosmological parameters are constrained using recent Planck and WMAP7 probe.  相似文献   

20.
In this paper, we investigate the model with a new type of interaction between generalized Chaplygin gas (GCG) and dark matter. It is shown that there exists a stable scaling attractor, which provides the possibility to alleviate the coincidence problem. The equation of state (EoS) of GCG approaches the attractor phase from either w g >?1 or w g w g w g w g >?1), and next cross again the phantom divide (the transition from w g >?1 to w g Q can change its sign from Q<0 to Q>0 as the universe expands, which is different from the usual interaction. Moreover, we investigate the model from statefinder viewpoint. The statefinder diagnostic can not only discriminate the model with different coupling constant but also distinguish the model from other dark energy models.  相似文献   

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