Bardeen black hole surrounded by perfect fluid dark matter

We derive an exact solution for a spherically symmetric Bardeen black hole surrounded by perfect fluid dark matter (PFDM). By treating the magnetic charge g and dark matter parameter \begin{document}$\alpha$\end{document} as thermodynamic variables, we find that the first law of thermodynamics and the corresponding Smarr formula are satisfied. The thermodynamic stability of the black hole is also studied. The results show that there exists a critical radius \begin{document}$r_{+}^{C}$\end{document} where the heat capacity diverges, suggesting that the black hole is thermodynamically stable in the range \begin{document}$0<r_{+}<r_{+}^{C}$\end{document} . In addition, the critical radius \begin{document}$r_{+}^{C}$\end{document} increases with the magnetic charge g and decreases with the dark matter parameter \begin{document}$\alpha$\end{document} . Applying the Newman-Janis algorithm, we generalize the spherically symmetric solution to the corresponding rotating black hole. With the metric at hand, the horizons and ergospheres are studied. It turns out that for a fixed dark matter parameter \begin{document}$\alpha$\end{document} , in a certain range, with the increase of the rotation parameter a and magnetic charge g, the Cauchy horizon radius increases while the event horizon radius decreases. Finally, we investigate the energy extraction by the Penrose process in a rotating Bardeen black hole surrounded by PFDM.     

Integrability of spinning particle motion in higher-dimensional rotating black hole spacetimes

We study the motion of a classical spinning particle (with spin degrees of freedom described by a vector of Grassmann variables) in higher-dimensional general rotating black hole spacetimes with a cosmological constant. In all dimensions n we exhibit n bosonic functionally independent integrals of spinning particle motion, corresponding to explicit and hidden symmetries generated from the principal conformal Killing-Yano tensor. Moreover, we demonstrate that in 4-, 5-, 6-, and 7-dimensional black hole spacetimes such integrals are in involution, proving the bosonic part of the motion integrable. We conjecture that the same conclusion remains valid in all higher dimensions. Our result generalizes the result of Page et?al. [Phys. Rev. Lett. 98, 061102 (2007)] on complete integrability of geodesic motion in these spacetimes.     

Classical non-Abelian particle in the field of a rotating colored black hole

The Hamilton-Jacobi method is used to derive and investigate the equations of motion of a classical non-Abelian particle in the field of a rotating colored black hole.Astrophysical Institute, Kazakh Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 3–7, May, 1993.     

Joule-Thomson expansion of the regular(Bardeen)-AdS black hole

We study the Joule-Thomson expansion of the regular black hole in an anti-de Sitter background,and obtain the inversion temperature for the Bardeen-AdS black hole in the extended phase space.We investigate the isenthalpic and inversion curves for the Bardeen-AdS black hole in the T-P plane and find that the intersection points between them are exactly the inversion points discriminating the heating from the cooling process.The inversion curve for the regular(Bardeen)-AdS black hole is not closed and there is only a lower inversion curve,in contrast to the Van der Waals fluid.Most importantly,we find that the ratio between the minimum inversion temperature and the critical temperature for the regular(Bardeen)-AdS black hole is 0.536622,which is larger than any known ratio for the singular black hole.The large ratio for the Bardeen-AdS black hole may be due to the repulsive de Sitter core near the origin of the regular black hole.     

Effects of acceleration on the collision of particles in the rotating black hole spacetime

We study the collision of two geodesic particles in the accelerating and rotating black hole spacetime and probe the effects of the acceleration of black hole on the center-of-mass energy of the colliding particles and on the high-velocity collision belts. We find that the dependence of the center-of-mass energy on the acceleration in the near event-horizon collision is different from that in the near acceleration-horizon case. Moreover, the presence of the acceleration changes the shape and position of the high-velocity collision belts. Our results show that the acceleration of black holes brings about richer physics for the collision of particles.     

P-v criticality and heat engine efficiency for Bardeen Einstein-Gauss-Bonnet AdS black hole

In this paper,we discuss the P-v criticality and the heat engine efficiency in the Bardeen EinsteinGauss-Bonnet (EGB) AdS black hole space-time.From the P-v plane in the extended phase space,we find that the Bardeen EGB-AdS black hole conforms to Van der Waals (VdW) liquid-gas systems in the extended phase space,and P_cv_/T_c=0.369 of the Bardeen EGB-AdS black hole system is between 0.3333 of the Gauss-Bonnet AdS black hole system and 0.375 of the VdW gas system in the 5-dimensions.Then we construct a heat engine by taking the Bardeen EGB-AdS black hole as the working substance,and consider a rectangle heat cycle in the P-v plane.We find that two cases with different Bardeen parameter e and Gauss-Bonnet parameter a both have the same situation,i.e.as the entropy difference between small black hole and large black hole S2 increases,the heat engine efficiency will increase.Furthermore,as the Bardeen parameter e increases,the efficiency will decrease.However,for the Gauss-Bonnet parameter a,the result is contrary.By comparing with the well-know Carnot heat engine efficiency,we have found the efficiency ratioη/η_c versus entropy S_2 is bounded below l,so it is coincided with the thermodynamical second law.     

Distribution of entropy of Bardeen regular black hole with corrected state density

We consider corrections to all orders in the Planck length on the quantum state density, and calculate the statistical entropy of the scalar field on the background of the Bardeen regular black hole numerically. We obtain the distribution of entropy which is inside the horizon of black hole and the contribution of the vicinity of horizon takes a great part of the whole entropy.     

Energy loss of a heavy particle near 3D charged rotating hairy black hole

In this paper, we start with a black brane and construct a specific space-time which violates hyperscaling. To obtain the string solution, we apply the Null-Melvin Twist and KK reduction. Using the difference action method, we study the thermodynamics of the system to obtain a Hawking–Page phase transition. To have hyperscaling violation, we need to consider $\theta =\frac{d}{2}.$ In this case, the free energy $F$ is always negative and our solution is thermal radiation without a black hole. Therefore, we find that there is no Hawking–Page transition. Also, we discuss the stability of the system and all thermodynamical quantities.     

Shadow images and observed luminosity of the Bardeen black hole surrounded by different accretions

In this paper, by exploring photon motion in the region near a Bardeen black hole, we studied the shadow and observed properties of the black hole surrounded by various accretion models. We analyzed the changes in shadow imaging and observed luminosity when the relevant physical parameters are changed. For the different spherical accretion backgrounds, we find that the radius of shadow and the position of the photon sphere do not change, but the observed intensity of shadow in the infalling accretion model is significantly lower than that in the static case. We also studied the contribution of the photon rings, lensing rings and direct emission to the total observed flux when the black hole is surrounded by an optically thin disk accretion. Under the different forms of the emission modes, the results show that the observed brightness is mainly determined by direct emission, while the lensing rings will provide a small part of the observed flux, and the flux provided by the photon ring is negligible. By comparing our results with the Schwarzschild spacetime, we find that the existence or change of relevant status parameters will greatly affect the shape and observed intensity of the black hole shadow. These results support the theory that the change of state parameter will affect the spacetime structure, thus affecting the observed features of black hole shadows.     

Hawking radiation of five-dimensional rotating black hole

Applying the Damour–Ruffini method, we have considered the Hawking radiation of the five-dimensional rotating black hole. When taking the energy conservation and angular momentum conservation into consideration and considering the reaction of the radiation of the particle to spacetime, we see that the exact radiation spectrum is not purely thermal and the angular momentum of the black hole is quantized.     

Five-dimensional black hole string backgrounds and brane universe acceleration

We examine background solutions of black hole type arising from the string effective action in five dimensions. We derive the unique metric — dilaton vacuum which is a Schwarzschild type black hole. It is found that it can be extended to incorporate electric charge without changing the topology of the three space. Kalb–Ramond charge may also be introduced if the three space is closed. The basic features of the cosmology induced on a three brane evolving in this background are also discussed.     

Supersymmetry of the extreme rotating toroidal black hole

We study the supersymmetry of the charged rotating toroidal black hole solutions found by Lemos and Zanchin, and show that the only configurations that are supersymmetric are: (i) the non-rotating electrically charged naked singularities already studied by Caldarelli and Klemm, and (ii) an extreme rotating toroidal black hole with zero magnetic and electric charges. For this latter case, the extreme uncharged black hole, we calculate the Killing spinors and show that the configuration preserves the same supersymmetries as the background spacetime.