相关论文: Black Hole versus Naked Singularity via Axial Pert…

Taking the extremal limit of a non-extremal Reissner-Nordstr\"om black hole (by externally varying the mass or charge), the region between the inner and outer event horizons experiences an interesting fate -- while this region is absent in…

We demonstrate the existence of spherically-symmetric truly naked black holes (TNBH) for which the Kretschmann scalar is finite on the horizon but some curvature components including those responsible for tidal forces as well as the energy…

While extreme black hole spacetimes with smooth horizons are known at the level of mathematics, we argue that the horizons of physical extreme black holes are effectively singular. Test particles encounter a singularity the moment they…

Motivated by cosmic censorship in general relativity and string theory, we extend Christodoulou's celebrated examples of naked singularity formation in the Einstein-massless scalar field system to include a positive or negative scalar…

It has recently been argued that extremal black holes can act as amplifiers of new physics, due to horizon instabilities that enhance the effects of ultraviolet corrections. In this paper, we revisit some of these claims and investigate the…

We consider particle collisions in the background of a nonextremal black hole. Two particles fall from infinity, particle 1 is fine-tuned (critical), collision occurs in its turning point. The first example is the Reissner-Nordstr\"{o}m…

The relationship between Hawking radiation emitted by non extremal and extremal Reissner Nordstrom black holes is critically analyzed. A careful study of a series of regular collapsing geometries reveals that the stress energy tensor stays…

We investigate the geometry near the horizon of a generic, four-dimensional extremal black hole. When the cosmological constant is negative, we show that (in almost all cases) tidal forces diverge as one crosses the horizon, and this…

The Hamiltonian actions for extreme and non-extreme black holes are compared and contrasted and a simple derivation of the lack of entropy of extreme black holes is given. In the non-extreme case the wave function of the black hole depends…

We study the Cauchy horizon (CH) singularity of a spherical charged black hole perturbed nonlinearly by a self-gravitating massless scalar field. We show numerically that the singularity is weak both at the early and at the late sections of…

Metrics representing black holes in General Relativity may exhibit naked singularities for certain values of their parameters. This is the case for super-extremal ($J^2 > M>0$) Kerr and super-extremal ($|Q|>M>0$) Reissner-N\"ordstrom…

We study 5-dimensional black holes in Einstein-Maxwell-Chern-Simons theory with free Chern-Simons coupling parameter. We consider an event horizon with spherical topology, and both angular momenta of equal magnitude. In particular, we study…

The singularitiy inside a spherical charged black hole, coupled to a spherical, massless scalar field is studied numerically. The profile of the characteristic scalar field was taken to be a power of advanced time with an exponent…

It is shown that the conserved charges on the event horizon and the Cauchy horizon associated to scalar perturbations on extremal black holes are externally measurable from null infinity. This suggests that these charges have the potential…

It was believed that when gravitational, electromagnetic and scalar waves interact, a spacelike curvature singularity or Cauchy horizon develops because of mutual focusing. We show with an exact solution that the collision of…

Non-extremal black holes are endowed with geometric invariants related to their horizon areas. We extend earlier work on hot attractor black holes to higher dimensions and add a scalar potential. In addition to the event and Cauchy…

We clarify the relation between gravitational entropy and the area of horizons. We first show that the entropy of an extreme Reissner-Nordstr\"om black hole is $zero$, despite the fact that its horizon has nonzero area. Next, we consider…

We provide evidence that ``super-extremal'' black hole space-times (either with charge larger than mass or angular momentum larger than mass), which contain naked singularities, are unstable under linearized perturbations. This is given by…

It is well known that an identical pair of extremal Reissner-Nordstrom black holes placed a large distance apart will exert no force on each other. In this paper, I establish that the same result holds in a very large class of…

We performed the first simulations of accretion onto the compact objects in the Reissner-Nordstr\"{o}m (RN) spacetime. The results obtained in general relativity are representative of those for spherically symmetric naked singularities and…