Effects Of Quintessence Research Articles

Echoes from charged black holes influenced by quintessence

In this paper, we investigate the effective potential and echoes from dyonic black holes with quintessence. For a dyonic black hole, the quasi-topological electromagnetism provides proper matter energy–momentum tensor to curve the spacetime, and quintessence strengthens this force. We find that when the effect of quintessence becomes stronger, the black hole potential will experience a series of complex transition processes between single-peak and double-peak. This causes repeated appearance and disappearance of the black hole echoes. In particular, we find that observer will receive a sudden vanishment of high-frequency echoes when quintessence remains a relatively strong effect.

Effects of quintessence on scattering and absorption sections of black holes

Basing on the ideas used by Kiselev, we study three black holes surrounded by quintessence and the effects of quintessence on the classical and semiclassical scattering cross-sections. In contrast, the absorption section is studied with the sinc approximation in the eikonal limit. For Schwarzschild, Reissner-Nordstr\"{o}m and Bardeen black holes surrounded by quintessence, the values critical of charges and the normalization factor are obtained. We also described the horizons and the extremal condition of the black holes surrounded by quintessence. By setting for the quintessence state parameter in two the particular cases w=-2/3 and w=-1/2.

Effects of quintessence and configuration of strings on the black holes of Lovelock-scalar gravity

Lovelock gravity containing dimensionally continued Euler densities can be considered as a natural extension of Einstein’s theory of gravity in higher dimensions such that the associated differential equations of motion are still second order. In this paper, the Lovelock gravity is coupled with a scalar field and dimensionally continued hairy black holes in the presence of quintessential matter and cloud of strings are analyzed. Thermodynamics of these black holes is discussed as well. It is shown that the thermodynamic quantities satisfy the generalized first law. The generalized Smarr’s relation is also derived and thermodynamic stability checked. Finally, black holes of general Lovelock-scalar theory are also briefly discussed.

Scattering and absorption cross sections of Schwarzschild–anti-de Sitter black hole with quintessence

In this paper, we study the scattering and absorption cross sections of a Schwarzschild–anti-de Sitter black hole surrounded by quintessence. The critical values of the cosmological constant and the normalization factor are obtained. We describe the event horizons and the extremal condition of the black hole surrounded by quintessence. The effects of quintessence on the classical and semi-classical scattering cross sections have been estimated. Additionally, the absorption cross section is studied with the sinc approximation in the eikonal limit. We consider the quintessence state parameter in the particular cases ω = –2/3 and –1/2.

Bending of light in a universe filled with quintessential dark energy

As a local effect of dynamical dark energy, bending of light in the presence of a spherically symmetric and static black hole surrounded by quintessence has been studied. Having in mind recent observational data, we have treated the problem as a deviation from Kottler space-time. This deviation is measured by a perturbation parameter $\varepsilon$ included in the equation of state parameter of quintessence as $\omega_q=-1+\frac{1}{3}\varepsilon$. Here, the deflection angle is calculated and then the result is compared with \cite{Arakida:2011th} in the limit $\varepsilon\rightarrow 0$ where the quintessence behaves like the cosmological constant. It is shown that unlike the cosmological constant, the effect of quintessence on the photon energy equation can not be absorbed into the definition of impact parameter. Moreover in this paper, we generalize the Kiselev black hole to the case that there is a modified Chaplygin gas as the dark energy component of the universe and show that the resulted metric can be reduced to the Kiselev metric by adjusting some arbitrary parameters.

The effect of quintessence in black hole spacetime

A new method is introduced to study the classification of spacetime, and spacetime horizons and timelike geodesics are investigated in the background spacetime of Reissner-Nordstrom-(anti-)de Sitter black hole surrounded by the quintessence (Q-RN(A)dS). We find that, for Q-RNAdS metric, there are two types of black holes: two horizons and four horizons. In a black hole spacetime of two horizons, the angular precession of the aphelion per revolution increases with the increase of the quintessence parameter $r_\text{q}$; while the number of aphelion per revolution increases with the decrease of the quintessence equation of state parameter $w_\text{q}$. This shows that the quintessence parameters $r_\text{q}$ and $w_\text{q}$ can be determined by measuring the angular precession and number of aphelion per revolution, respectively. For Q-RNdS metric there are two cases: one horizon and three horizons. The Q-RNdS metric of one horizon describes the de Sitter-like spacetime, which has a naked singularity at $r=0$. It is interesting to note that any particle never reaches the singularity, since the effective potential is infinite at the point. On the other hand, the quintessence has no significant on the geodesics in de Sitter-like spacetime. It is worth pointing out that there are no bound states for the Q-RNAdS spacetime with four horizons and the Q-RNdS spacetime with three horizons.

Effects of dark energy on geodesics and thermodynamics of the Schwarzschild-de Sitter space-time

The effects of quintessence on geodesics and thermodynamics of the Schwarzschild-de Sitter black hole are studied and the results are compared with the case without the presence of quintessence. We show that the presence of quintessence increases the entropy and heat capacity of the Schwarzschild-de Sitter black hole and decreases the mass and temperature of this black hole. In particular, we focused on types of orbits and we found that the coordinate time, circular orbits, period of the circular orbits and the angle of deflection of light for this black hole increase in quintessence field while the quintessence decreases the effective potential, force on the massless particle, Lyapunov exponent $\lambda $ and closest approach.

State equations for massless spin fields in static spherical spacetime filled with quintessence

The entropy density, energy density, pressure and equation of state for the gases of massless particles with spin s ≤ 2 around the static spherical black hole with quintessence are investigated by using the brick-wall method. It is shown that the state equations for spin fields in curved spacetime do not take the same forms as that in flat spacetime and contain additional terms with spin dependence. Then the character of the terms and the effect of quintessence and spin on them are discussed.

Effects of quintessence on observations of Type Ia supernovae in the clumpy universe

We discuss the amplification dispersion in the observed luminosity of standard candles, such as supernovae (SNe) of Type Ia, induced by gravitational lensing in a universe with dark energy (quintessence). We derive the main features of the magnification probability distribution function (pdf) of SNe in the framework of on average Friedmann-Lemaitre-Robertson-Walker (FLRW) models for both lensing by large-scale structures and compact objects. Analytic expressions, in terms of hypergeometric functions, for luminosity distance-redshift relations in a flat universe with homogeneous dark energy have been corrected for the effects of inhomogeneities in the pressureless dark matter (DM). The magnification pdf is strongly dependent on the equation of state, ω Q , of the quintessence. With no regard to the nature of DM (microscopic or macroscopic), the dispersion increases with the redshift of the source and is maximum for dark energy with very large negative pressure; the effects of gravitational lensing on the magnification pdf, i.e. the mode biased towards de-amplified values and the long tail towards large magnifications, are reduced for both microscopic DM and quintessence with an intermediate ω Q . Different equations of state of the dark energy can deeply change the dispersion in amplification for the projected observed samples of SNe Ia by future space-borne missions. The 'noise' in the Hubble diagram due to gravitational lensing strongly affects the determination of the cosmological parameters from SNe data. The errors on the pressureless matter density parameter, Ω M , and on ω Q are maximum for quintessence with not very negative pressure. The effect of the gravitational lensing is of the same order as the other systematics affecting observations of SNe Ia. As a result of the lensing by large-scale structures, in a flat universe with Ω M = 0.4, at z = 1 a cosmological constant (ω Q = -1) can be interpreted as dark energy with ω Q < -0.84 (at 2a confidence limit).