We examine the linear stability of various configurations in Bose-Einstein condensates with sonic horizons. These configurations are chosen in analogy with gravitational systems with a black hole horizon, a white hole horizon and a combination of both. We discuss the role of different boundary conditions in this stability analysis, paying special attention to their meaning in gravitational term...

Mobile Ad-hoc network (MANET) has become an individual part for communication for mobile device. Therefore, interest in research of Mobile Ad-hoc network has been growing since last few years. Due to the open medium, dynamic network topology, autonomous terminal, lack of centralized monitoring and lack of management point Mobile Ad-hoc network are highly vulnerable to security attacks compared ...

We relate various black hole solutions in the near-horizon region to black hole solutions in two-dimensional dilaton gravity theories in order to argue that the thermodynamics of black holes in D>4 can be effectively described by the thermodynamics of black holes in two-dimensional dilaton gravity theories. We show that the Bekenstein-Hawking entropies of single-charged dilatonic black holes an...

We describe some specific quantum black hole model. It is pointed out that the origin of a black hole entropy is the very process of quantum gravitational collapse. The quantum black hole mass spectrum is extracted from the mass spectrum of the gravitating source. The classical analog of quantum black hole is constructed.

We study the Hawking radiation in a monopole black hole background in SO(3) Einstein-Yang-Mills-Higgs system. We only consider a massless scalar field which does not couple with the Yang-Mills field or Higgs field around the black hole. Starting from a Reissner-Nortström black hole, and assuming that it transits into a monopole black hole at a critical point, we find that the evaporation rate w...

The term black hole is usually associated with a large astrophysical object that has formed due to huge gravitational fields that can arise in the center of massive concentrations (see, e.g., ). However, the black hole is an object in itself which should be studied within the domain of physics, irrespective of the interactions with exterior astrophysical plasmas which excite, and are excited by...

As a first step towards understanding the angular momentum evolutionary history of black holes in merging black-hole/neutron-star binaries, we perform population synthesis calculations to track the distribution of accretion histories of compact objects in such binaries. We find that there are three distinct processes can possibly contribute to the black-hole spin magnitude: a birth spin for the...

An exact energy expression for a physical black hole is derived by considering the escape of a photon from the black hole. The mass of the black hole within its horizon is found to be twice its mass as observed at infinity. This result is important in understanding gravitational waves in black hole collisions.

The origin of jets emitted from black holes is not well understood; however, there are two possible energy sources: the accretion disk or the rotating black hole. Magnetohydrodynamic simulations show a well-defined jet that extracts energy from a black hole. If plasma near the black hole is threaded by large-scale magnetic flux, it will rotate with respect to asymptotic infinity, creating large...

In general relativity, the spacetimes of black holes have three fundamental properties: (i) they are same, to lowest order in spin, as metrics stellar objects; (ii) independent mass when expressed geometric units; and (iii) described by Kerr metric. this paper, we quantify upper bounds on potential black-hole metric deviations imposed observations shadows binary inspirals explore current experi...