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70 - Molin Liu , Benhai Yu , Fei Yu 2010
After the previous work on gravitational frequency shift, light deflection (arXiv:1003.5296) and perihelion advance (arXiv:0812.2332), we calculate carefully the fourth gravity test, i.e. radar echo delay in a central gravity field surrounded by stat ic free quintessence matter, in this paper. Through the Lagrangian method, we find the influence of the quintessence matter on the time delay of null particle is presence by means of an additional integral term. When the quintessence field vanishes, it reduces to the usual Schwarzschild case naturally. Meanwhile, we also use the data of the Viking lander from the Mars and Cassini spacecraft to Saturn to constrain the quintessence field. For the Viking case, the field parameter $alpha$ is under the order of $10^{-9}$. However, $alpha$ is under $10^{-18}$ for the Cassini case.
108 - Fei Yu , Molin Liu , Yuanxing Gui 2010
We employ the metric of Schwarzschild space surrounded by quintessential matter to study the trajectories of test masses on the motion of a binary system. The results, which are obtained through the gradually approximate approach, can be used to sear ch for dark energy via the difference of the azimuth angle of the pericenter. The classification of the motion is discussed.
62 - Jianbo Lu , Lixin Xu , Molin Liu 2008
We use recently observed data: the 192 ESSENCE type Ia supernovae (SNe Ia), the 182 Gold SNe Ia, the 3-year WMAP, the SDSS baryon acoustic peak, the X-ray gas mass fraction in clusters and the observational $H(z)$ data to constrain models of the acce lerating universe. Combining the 192 ESSENCE data with the observational $H(z)$ data to constrain a parameterized deceleration parameter, we obtain the best fit values of transition redshift and current deceleration parameter $z_{T}=0.632^{+0.256}_{-0.127}$, $q_{0}=-0.788^{+0.182}_{-0.182}$. Furthermore, using $Lambda$CDM model and two model-independent equation of state of dark energy, we find that the combined constraint from the 192 ESSENCE data and other four cosmological observations gives smaller values of $Omega_{0m}$ and $q_{0}$, but a larger value of $z_{T}$ than the combined constraint from the 182 Gold data with other four observations. Finally, according to the Akaike information criterion it is shown that the recently observed data equally supports three dark energy models: $Lambda$CDM, $w_{de}(z)=w_{0}$ and $w_{de}(z)=w_{0}+w_{1}ln(1+z)$.
Based on the 4D momentum, the influence of quintessence on the gravitational frequency shift and the deflection of light are examined in modified Schwarzschild space. We find that the frequency of photon depends on the state parameter of quintessence $w_q$: the frequency increases for $-1<w_q<-1/3$ and decreases for $-1/3<w_q<0$. Meanwhile, we adopt an integral power number $a$ ($a = 3omega_q + 2$) to solve the orbital equation of photon. The photons potentials become higher with the decrease of $omega_q$. The behavior of bending light depends on the state parameter $omega_q$ sensitively. In particular, for the case of $omega_q = -1$, there is no influence on the deflection of light by quintessence. Else, according to the H-masers of GP-A redshift experiment and the long-baseline interferometry, the constraints on the quintessence field in Solar system are presented here.
In this paper, we study the quantum statistical entropy in a 5D Ricci-flat black string solution, which contains a 4D Schwarzschild-de Sitter black hole on the brane, by using the improved thin-layer method with the generalized uncertainty principle. The entropy is the linear sum of the areas of the event horizon and the cosmological horizon without any cut-off and any constraint on the bulks configuration rather than the usual uncertainty principle. The systems density of state and free energy are convergent in the neighborhood of horizon. The small-mass approximation is determined by the asymptotic behavior of metric function near horizons. Meanwhile, we obtain the minimal length of the position $Delta x$ which is restrained by the surface gravities and the thickness of layer near horizons.
As one exact candidate of the higher dimensional black hole, the 5D Ricci-flat Schwarzschild-de Sitter black string space presents something interesting. In this paper, we give a numerical solution to the real scalar field around the Nariai black hol e by the polynomial approximation. Unlike the previous tangent approximation, this fitting function makes a perfect match in the leading intermediate region and gives a good description near both the event and the cosmological horizons. We can read from our results that the wave is close to a harmonic one with the tortoise coordinate. Furthermore, with the actual radial coordinate the waves pile up almost equally near the both horizons.
56 - Molin Liu , Hongya Liu 2008
In this paper, the statistical-mechanical entropies of 5D Ricci-flat black string is calculated through the wave modes of the quantum field with improved thin-layer brick-wall method. The modes along the fifth dimension are semi-classically quantized by Randall-Sundrum mass relationship. We use the two-dimensional area to describe this black strings entropy which, in the small-mass approximation, is a linear sum of the area of the black hole horizon and the cosmological horizon. The proportionality coefficients of entropy are discretized with quantized extra dimensional modes. It should be noted that the small-mass approximation used in our calculation is naturally justified by the assumption that the two branes are located far apart.
As one of the fitting methods, the polynomial approximation is effective to process sophisticated problem. In this paper, we employ this approach to handle the scattering of scalar field around the Schwarzschild-de Sitter black-hole. The complex rela tionship between tortoise coordinate and radial coordinate is replaced by the approximate polynomial. The Schr$ddot{o}$dinger-like equation, the real boundary conditions and the polynomial approximation construct a full Sturm-Liouville type problem. Then this boundary value problem can be solved numerically according to two limiting cases: the first one is the Nariai black-hole whose horizons are close to each other, the second one is when the horizons are widely separated. Compared with previous results (Brevik and Tian), the field near the event horizon and cosmological horizon can have a better description.
As one candidate of the higher dimensional black holes, the 5D Ricci-flat black string is considered in this paper. By means of a non-trivial potential $V_{n}$, the quasi-normal modes of a massless scalar field around this black string space is studi ed. By using the classical third order WKB approximation, we analyse carefully the evolution of frequencies in two aspects, one is the induced cosmological constant $Lambda$ and the other is the quantum number $n$. The massless scalar field decays more slowly because of the existences of the fifth dimension and the induced cosmological constant. If extra dimension has in fact existed near black hole, those quasi-normal frequencies may have some indication on it.
The Nariai black hole, whose two horizons are lying close to each other, is an extreme and important case in the research of black hole. In this paper we study the evolution of a massless scalar field scattered around in 5D Schwarzschild-de Sitter bl ack string space. Using the method shown by Brevik and Simonsen (2001) we solve the scalar field equation as a boundary value problem, where real boundary condition is employed. Then with convenient replacement of the 5D continuous potential by square barrier, the reflection and transmission coefficients ($R, T$) are obtained. At last, we also compare the coefficients with usual 4D counterpart.
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