The characteristics of black-hole X-ray binaries can be used to obtain information about their evolutionary history and the process of black-hole formation. In this paper I focus on systems with donor masses lower than the inferred black-hole masses. Current models for the evolution of hydrogen-rich, massive stars and of helium stars losing mass in a wind cannot explain the current sample of bl...

We review the present status of black hole thermodynamics. Our review includes discussion of classical black hole thermodynamics, Hawking radiation from black holes, the generalized second law, and the issue of entropy bounds. A brief survey also is given of approaches to the calculation of black hole entropy. We conclude with a discussion of some unresolved open issues.

When some magnetic field lines connect a Kerr black hole with a disk rotating around it, energy and angular momentum are transferred between them. If the black hole rotates faster than the disk, ca&solm0;GMH>0.36 for a thin Keplerian disk, then energy and angular momentum are extracted from the black hole and transferred to the disk (MH is the mass and aMH is the angular momentum of the black h...

In recent years mobile networks have expanded dramatically, compared with other wireless networks. Routing protocols in these networks are designed with the assumption that there is no attacker node, so routing protocols are vulnerable to various attacks in these networks. In this paper, we review the network layer attacks and then we simulate the impact of black hole attack on ad hoc on demand...

We construct a model for black hole formation in galactic bulges. The initial state is a slowly rotating isothermal sphere, with an effective transport speed and rotation rate Q. The black hole mass is determined when the aeff centrifugal radius of the collapse flow exceeds the capture radius of the central black hole. This model reproduces the observed correlation between black hole masses and...

A black hole is a highly harmful stationary process residing in a node of a network and destroying all mobile agents visiting the node, without leaving any trace. We consider the task of locating a black hole in a (partially) synchronous network, assuming an upper bound on the time of any edge traversal by an agent. The minimum number of agents capable to identify a black hole is two. For a giv...

We follow the evolution of IC10 X-1, the extragalactic binary hosting the most massive known stellar black hole with the mass of at least 23 M⊙. A massive companion of this black hole is a 35 M⊙ helium star that will very soon form another black hole. We demonstrate that this system will become a close double black hole binary with coalescence time of ∼ 2 − 3Gyr. We estimate that a detection ra...

The central black-hole masses of 85 radio-loud quasars are estimated using available data of Hβ line-width and optical continuum luminosity. The vast majority of the quasars in this sample have black-hole masses larger than 108M⊙, while a few quasars may contain relatively smaller black-holes. It is found that the radio-loudness decreases with the black-hole mass.

The stability of the Schwarzschild black hole is studied. Using the Painlevé coordinate, our region can be defined as the black-hole-connected region (r > 2m, see text) of the Schwarzschild black hole or the white-hole-connected region (r > 2m, see text) of the Schwarzschild black hole. We study the stable problems of the black-holeconnected region . The conclusions are: (1) in the black-hole-c...

A black hole considered as a part of a thermodynamical system possesses the Bekenstein-Hawking entropy SH = AH/(4l 2 P), where AH is the area of a black hole surface and lP is the Planck length. Recent attempts to connect this entropy with dynamical degrees of freedom of a black hole generically did not provide the universal mechanism which allows one to obtain this exact value. We discuss the ...