جستجوی مقالات مرتبط با کلیدواژه "black hole" در نشریات گروه "فیزیک"

In this paper, null geodesics for a symmergent black hole are investigated. The geodesic equation of this space time are solved analytically according to the Weierstrass elliptic function. Also, the effective potential is obtained and plotted. Finally, using the form of effective potential and obtained analytical solution of geodesic equations, some possible types of orbits related to null geodesics are demonstrated.

This letter investigates non-perturbative corrections to the entropy of black holes and their impact on the associated statistical mechanics and thermodynamics. An exponential correction term to the entropy is proposed, modifying the standard Bekenstein-Hawking formula. The corrected partition function is derived, enabling calculations of thermodynamic quantities like the Helmholtz free energy. For the Schwarzschild black hole case, the free energy reduces to the standard result when the correction term vanishes, providing a consistency check. The implications of these non-perturbative entropy corrections for the statistical mechanics and thermodynamic descriptions of black holes are discussed.

In this paper, we consider an $\alpha^{\prime}$ corrected Reissner-Nordstr\"{o}m AdS black hole to study thermodynamics. We study the $P-V$ criticality and thermodynamical stability of black hole. We obtained a first-order phase transition which may be interpreted as the large/small black hole phase transition. Therefore, we obtained a van der Waals behaviour and obtained critical points. Finally, we calculate quantum work which is used to resolve the information loss paradox.

In this paper, we consider a metric of a rotating black hole in conformal gravity. We calculate the thermodynamical quantities for this rotating black hole including Hawking temperature and entropy in four-dimensional space-time, as we obtain the effective value of Komar angular momentum. The result is valid on the event horizon of the black hole and at any radial distance out of it. Also, we verify that the first law of thermodynamics will be held for this type of black hole.

Shear viscosity to entropy ratio has a universal lower bound which may be violated under some effects. This paper would like to consider non-perturbative quantum corrections on the mentioned ratio in a STU black hole background. The STU model is a gravitational background that is the holographic dual of $N=4$ super Yang-Mills quark-gluon plasma with the chemical potential. Non-perturbative corrections to the black hole entropy emerge as an exponential term which may affect the shear viscosity to entropy ratio. All possibilities will study in this paper to extract the shear viscosity of a quark-gluon plasma. We find that the universal lower bound the shear viscosity to entropy ratio may be violated due to the non-perturbative corrections.

In this paper, we consider a (2+1) D black hole conformally coupled to a masslessscalar. Then the geodesic motion of test particles and light rays in the vicinity of the spacetime ofthis black hole is studied. Moreover, the geodesic equations are solved analytically according toWeierstrass elliptic and derivatives of Kleinian sigma hyperelliptic functions. Also, the possibleorbits are discussed and classified according to the particle's energy and angular momentum.

In this work, we consider a static spherically symmetric charged regular black hole to investigate arbitrarily high centre of mass energy near the horizon with particle collision for extremal case in the equatorial plane ($theta=pi/2$). Here we also study circular geodesics and find the ISCO and MBCO redii. We analysis the two neutral particles collision with same masses and different masses. Also we analyze the particle collision with massless photon and photon-photon collision near the horizon of this regular black hole to calculate centre of mass energy.

The existence of outflow in the advection dominated accretion flows has been confirmed by both numerical simulations and observations. The outow models for ADAF have been investigated by several groups with a simple self similar solution. But this solution is inaccurate at the inner regions and can not explain the emitted spectrum of the flow; so, it is necessary to obtain a global solution for ADAFs with outflow. In this paper, we use a simplified global solution to study the structure of ADAF in the presence of outflow. In this method which is proposed by Yuan et al (2008, hereafter YMN08), the radial momentum equation is replaced by a simple algebraic relation between angular velocity and Keplerian angular velocity to avoid the difficulty of the calculation of global solution. We consider the radial dependence for mass accretion rate M =M out(r/rout)swhere s is a constant and we do not change the other dynamical equations. We investigate the variation of physical quantity of accretion flow which is caused by outflow. The results that we obtained comply with our expectations from the influence of outflow on the structure of accretion flow.