We consider the DBI action for the D-branes with the dynamic embeddings in the background produced by p-branes. For the D-brane with the special topology we obtain two Hublle parameters on this brane. The condition for the equality of these parameters is analyzed. In the special case a mass and a charge of the background p-branes are derived from this condition.
Holographic Thermodynamic on the Brane in Topological Reissner-Nordström de Sitter Space
我们考虑拓扑Reissner-Nordström de Sitter黑洞的体背景中的膜宇宙。当膜穿过黑洞视界或宇宙学视界时,对偶CFT的热力学量(包括熵)具有通常的特殊形式,用哈勃参数及其时间导数表示.对于Friedmann方程中的任意曲率参数$k$,我们得到了带电荷和宇宙学常数的CFT的广义Cardy-Verlinde公式.
We investigate the cosmological consequences of a two brane system embedded in a higher dimensional background spacetime with a compactified extra dimension described with an action that include the intrinsic curvature for each brane. We find that the dynamics of each brane is related to the other by means of cosmological restrictions that involve the scale factors, the equation of state parameters and the Hubble parameters of the two branes. We analyze the evolution of the scale factor and the equation of state parameter for the hidden brane when in the visible brane is present a cosmological…
When a brane-anti-brane system includes two tachyons, each of them produces a BIoninc wormhole. These wormholes interact with each other and form 4 regions. Two of the regions are related to the independent BIons which have been considered previously. However, two new regions correspond to the interacting BIons in which the cosmic parameters act oppositely to each other. We obtain the Hubble parameter and energy density of the universes in the new regions and show that by expanding a universe in one region, the universe in the other region contracts. Also, the evolution of the universes depend…
The cosmology of brane induced gravity in six infinite dimensions is investigated. It is shown that a brane with Friedmann-Robertson-Walker symmetries necessarily acts as a source of cylindrically symmetric gravitational waves, so called Einstein-Rosen waves. Their existence essentially distinguishes this model from its codimension-one counterpart and necessitates solving the nonlinear system of bulk and brane-matching equations. A numerical analysis is performed and two qualitatively different and dynamically separated classes of cosmologies are derived: degravitating solutions for which the …
Brane cosmology from observational surveys and its comparison with standard FRW cosmology
研究了膜上的几种暗能量模型。并在四维Friedmann-Robertson-Walker宇宙学框架下与相应的理论进行了比较。为了约束所考虑的模型的参数,最近的观测数据,包括SNIa视星等测量,重子声学振荡结果,哈勃参数演化数据和物质密度扰动。得到了远程平行理论中所谓的{ \it state finder}参数的显式公式,这可能有助于测试这些模型,并建立环量子宇宙学和膜宇宙学之间的联系。它的结论是,联合分析,因为这里开发的一个允许估计,在一个非常方便的方式,可能的偏差,从标准的弗里德曼-罗伯逊-沃克的真实宇宙宇宙学。
In recent years the discrepancy in the value of the Hubble parameter has been growing. Recently, there are works supporting the proposal that the uncertainty principles can solve the Hubble tension. Motivated by this proposal, we work with an isotropic and homogeneous FRW universe, obtain its Hamiltonian equations, and thus, the Hubble parameter through the first Friedmann equation. In the context of GUP and EUP models, the Hubble parameter is modified. Since the fingerprints of quantum gravity are imprinted on the CMB, we consider the GUP/EUP-modified Hubble parameter in the first Friedmann e…
We compare several well-known cosmological dark energy models using observational data coming both from type Ia supernovae and from Hubble parameter measurements. First we use supernovae data to determine the free parameters of each model except for the Hubble constant $H_0$. Then, we use the Hubble parameter measurements to determine $H_0$, and finally the age of the Universe for each model is computed. Our main numerical results are summarized in tables, and they are briefly discussed. The prediction for the decelerating parameter as a function of red-shift for each model is shown in the sam…
We present simple solutions of IKKT-type matrix models that can be viewed as quantized homogeneous and isotropic cosmological space-times, with finite density of microstates and a regular Big Bang (BB). The BB arises from a signature change of the effective metric on a fuzzy brane embedded in Lorentzian target space, in the presence of a quantized 4-volume form. The Hubble parameter is singular at the BB, and becomes small at late times. There is no singularity from the target space point of view, and the brane is Euclidean "before" the BB. Both recollapsing and expanding universe solutions ar…
Allowing for a nonvanishing spin tensor for cold dark matter ($ω_{\mathrm{DM}}=0$) has the consequence of giving rise to an effective $\mathrm{FLRW}$ dynamics with a small negative barotropic constant for an effective dark matter density ($-1/3<ω_{\mathrm{eff}}\leq0$). This turns out to solve the Hubble parameter tension in a straightforward way.
Cosmic microwave background (CMB) anisotropy (spatial inhomogeneity) data provide the tightest constraints on the Hubble constant, matter density, spatial curvature, and dark energy dynamics. Other data, sensitive to the evolution of only the spatially homogeneous part of the cosmological model, such as Type Ia supernova apparent magnitude, baryon acoustic oscillation distance, and Hubble parameter measurements, can be used in conjunction with the CMB data to more tightly constrain parameters. Recent joint analyses of CMB and such non-CMB data indicate that slightly closed spatial hypersurface…
In this paper we use all available baryon acoustic oscillation, Hubble parameter, and quasar angular size data to constrain six dark energy cosmological models, both spatially flat and non-flat. Depending on the model and data combination considered, these data mildly favor closed spatial hypersurfaces (by as much as $1.7σ$) and dark energy dynamics (up to a little over $2σ$) over a cosmological constant $Λ$. The data also favor, at $1.8σ$ to $3.4σ$, depending on the model and data combination, a lower Hubble constant than what is measured from the local expansion rate.
We use Pantheon Type Ia supernova (SN Ia) apparent magnitude, DES-3yr binned SN Ia apparent magnitude, Hubble parameter, and baryon acoustic oscillation measurements to constrain six spatially flat and non-flat cosmological models. These sets of data provide mutually consistent cosmological constraints in the six cosmological models we study. A joint analysis of these data sets provides model-independent estimates of the Hubble constant, $H_0=68.8\pm1.8\ \rm{km \ s^{-1} \ Mpc^{-1}}$, and the non-relativistic matter density parameter, $Ω_{\rm m_0}=0.294\pm0.020$. Although the joint constraints …