3,710 research outputs found
A note on the quantization of a multi-horizon black hole
We consider the quasinormal spectrum of a charged scalar field in the
(charged) Reissner-Nordstrom spacetime, which has two horizons. The spectrum is
characterized by two distinct families of asymptotic resonances. We suggest and
demonstrate the according to Bohr's correspondence principle and in agreement
with the Bekenstein-Mukhanov quantization scheme, one of these resonances
corresponds to a fundamental change of Delta A=4hbar ln2 in the surface area of
the black-hole outer horizon. The second asymptotic resonance is associated
with a fundamental change of Delta Atot=4hbar ln3 in the total area of the
black hole (in the sum of the surface areas of the inner and outer horizons),
in accordance with a suggestion of Makela and Repo.Comment: 6 page
Dyonic Kerr-Newman black holes, complex scalar field and Cosmic Censorship
We construct a gedanken experiment, in which a weak wave packet of the
complex massive scalar field interacts with a four-parameter (mass, angular
momentum, electric and magnetic charges) Kerr-Newman black hole. We show that
this interaction cannot convert an extreme the black hole into a naked
sigularity for any black hole parameters and any generic wave packet
configuration. The analysis therefore provides support for the weak cosmic
censorship conjecture.Comment: Refined emphasis on the weak cosmic censorship conjecture,
conclusions otherwise unchanged. Also, two sections merged, literature review
updated, references added, a few typos correcte
Time-Dependent Random Walks and the Theory of Complex Adaptive Systems
Motivated by novel results in the theory of complex adaptive systems, we
analyze the dynamics of random walks in which the jumping probabilities are
{\it time-dependent}. We determine the survival probability in the presence of
an absorbing boundary. For an unbiased walk the survival probability is
maximized in the case of large temporal oscillations in the jumping
probabilities. On the other hand, a random walker who is drifted towards the
absorbing boundary performs best with a constant jumping probability. We use
the results to reveal the underlying dynamics responsible for the phenomenon of
self-segregation and clustering observed in the evolutionary minority game.Comment: 5 pages, 2 figure
Best Approximation to a Reversible Process in Black-Hole Physics and the Area Spectrum of Spherical Black Holes
The assimilation of a quantum (finite size) particle by a
Reissner-Nordstr\"om black hole inevitably involves an increase in the
black-hole surface area. It is shown that this increase can be minimized if one
considers the capture of the lightest charged particle in nature. The
unavoidable area increase is attributed to two physical reasons: the Heisenberg
quantum uncertainty principle and a Schwinger-type charge emission (vacuum
polarization). The fundamental lower bound on the area increase is ,
which is smaller than the value given by Bekenstein for neutral particles.
Thus, this process is a better approximation to a reversible process in
black-hole physics. The universality of the minimal area increase is a further
evidence in favor of a uniformly spaced area spectrum for spherical quantum
black holes. Moreover, this universal value is in excellent agreement with the
area spacing predicted by Mukhanov and Bekenstein and independently by Hod.Comment: 10 page
Kerr black hole quasinormal frequencies
Black-hole quasinormal modes (QNM) have been the subject of much recent
attention, with the hope that these oscillation frequencies may shed some light
on the elusive theory of quantum gravity. We compare numerical results for the
QNM spectrum of the (rotating) Kerr black hole with an {\it exact} formula
Re, which is based on Bohr's correspondence
principle. We find a close agreement between the two. Possible implications of
this result to the area spectrum of quantum black holes are discussed.Comment: 3 pages, 2 figure
Evidence for a null entropy of extremal black holes
We present some arguments in support of a {\it zero} entropy for {\it
extremal} black holes. These rely on a combination of both quantum,
thermodynamic, and statistical physics arguments. This result may shed some
light on the nature of these extreme objects. In addition, we show that within
a {\it quantum} framework the capture of a particle by an initially extremal
black hole always results with a final nonextremal black hole.Comment: 11 page
Black-hole radiation, the fundamental area unit, and the spectrum of particle species
Bekenstein and Mukhanov have put forward the idea that, in a quantum theory
of gravity a black hole should have a discrete mass spectrum with a concomitant
{\it discrete} line emission. We note that a direct consequence of this
intriguing prediction is that, compared with blackbody radiation, black-hole
radiance is {\it less} entropic. We calculate the ratio of entropy emission
rate from a quantum black hole to the rate of black-hole entropy decrease, a
quantity which, according to the generalized second law (GSL) of
thermodynamics, should be larger than unity. Implications of our results for
the GSL, for the value of the fundamental area unit in quantum gravity, and for
the spectrum of massless particles in nature are discussed.Comment: 4 page
Late-Time Evolution of Realistic Rotating Collapse and The No-Hair Theorem
We study analytically the asymptotic late-time evolution of realistic
rotating collapse. This is done by considering the asymptotic late-time
solutions of Teukolsky's master equation, which governs the evolution of
gravitational, electromagnetic, neutrino and scalar perturbations fields on
Kerr spacetimes. In accordance with the no-hair conjecture for rotating
black-holes we show that the asymptotic solutions develop inverse power-law
tails at the asymptotic regions of timelike infinity, null infinity and along
the black-hole outer horizon (where the power-law behaviour is multiplied by an
oscillatory term caused by the dragging of reference frames). The damping
exponents characterizing the asymptotic solutions at timelike infinity and
along the black-hole outer horizon are independent of the spin parameter of the
fields. However, the damping exponents at future null infinity are spin
dependent. The late-time tails at all the three asymptotic regions are
spatially dependent on the spin parameter of the field. The rotational dragging
of reference frames, caused by the rotation of the black-hole (or star) leads
to an active coupling of different multipoles.Comment: 16 page
Effects of Pair Creation on Charged Gravitational Collapse
We investigate the effects of pair creation on the internal geometry of a
black hole, which forms during the gravitational collapse of a charged massless
scalar field. Classically, strong central Schwarzschild-like singularity forms,
and a null, weak, mass-inflation singularity arises along the Cauchy horizon,
in such a collapse. We consider here the discharge, due to pair creation, below
the event horizon and its influence on the {\it dynamical formation} of the
Cauchy horizon. Within the framework of a simple model we are able to trace
numerically the collapse. We find that a part of the Cauchy horizon is replaced
by the strong space-like central singularity. This fraction depends on the
value of the critical electric field, , for the pair creation.Comment: LaTex, 27 pages, including 14 figures. Some points are clarified,
typos corrected. Version accepted for publication in Phys.Rev.
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