161 research outputs found
On the semiclassical treatment of Hawking radiation
In the context of the semiclassical treatment of Hawking radiation we prove
the universality of the reduced canonical momentum for the system of a massive
shell self gravitating in a spherical gravitational field within the Painlev\'e
family of gauges. We show that one can construct modes which are regular on the
horizon both by considering as hamiltonian the exterior boundary term and by
using as hamiltonian the interior boundary term. The late time expansion is
given in both approaches and their time Fourier expansion computed to reproduce
the self reaction correction to the Hawking spectrum.Comment: 18 pages, LaTeX, Corrected typo
Local temperature for dynamical black holes
A local Hawking temperature was recently derived for any future outer
trapping horizon in spherical symmetry, using a Hamilton-Jacobi tunneling
method, and is given by a dynamical surface gravity as defined geometrically.
Descriptions are given of the operational meaning of the temperature, in terms
of what observers measure, and its relation to the usual Hawking temperature
for static black holes. Implications for the final fate of an evaporating black
hole are discussed.Comment: 7 pages, contribution to Proceedings of ERE200
Hamilton-Jacobi Method and Gravitation
Studying the behaviour of a quantum field in a classical, curved, spacetime
is an extraordinary task which nobody is able to take on at present time.
Independently by the fact that such problem is not likely to be solved soon,
still we possess the instruments to perform exact predictions in special,
highly symmetric, conditions. Aim of the present contribution is to show how it
is possible to extract quantitative information about a variety of physical
phenomena in very general situations by virtue of the so-called Hamilton-Jacobi
method. In particular, we shall prove the agreement of such semi-classical
method with exact results of quantum field theoretic calculations.Comment: To appear in the proceedings of "Cosmology, the Quantum Vacuum, and
Zeta Functions": A workshop with a celebration of Emilio Elizalde's Sixtieth
birthday, Bellaterra, Barcelona, Spain, 8-10 Mar 201
What kinds of coordinate can keep the Hawking temperature invariant for the static spherically symmetric black hole?
By studying the Hawking radiation of the most general static spherically
symmetric black hole arising from scalar and Dirac particles tunnelling, we
find the Hawking temperature is invariant in the general coordinate
representation (\ref{arbitrary1}), which satisfies two conditions: a) its
radial coordinate transformation is regular at the event horizon; and b) there
is a time-like Killing vector.Comment: 10 page
Tunnelling through black rings
Hawking radiation of black ring solutions to 5-dimensional
Einstein-Maxwell-dilaton gravity theory is analyzed by use of the
Parikh-Wilczek tunnelling method. To get the correct tunnelling amplitude and
emission rate, we adopted and developed the Angheben-Nadalini-Vanzo-Zerbini
covariant approach to cover the effects of rotation and electronic discharge
all at once, and the effect of back reaction is also taken into account. This
constitute a unified approach to the tunnelling problem. Provided the first law
of thermodynamics for black rings holds, the emission rate is proportional to
the exponential of the change of Bekenstein-Hawking entropy. Explicit
calculation for black ring temperatures agree exactly with the results obtained
via the classical surface gravity method and the quasilocal formalism.Comment: 10 pages, V2: various modifications throughout the text, plus a lot
of newly added reference
On the Hawking radiation as tunneling for a class of dynamical black holes
The instability against emission of massless particles by the trapping
horizon of an evolving black hole is analyzed with the use of the
Hamilton-Jacobi method. The method automatically selects one special expression
for the surface gravity of a changing horizon. Indeed, the strength of the
horizon singularity turns out to be governed by the surface gravity as was
defined a decade ago by Hayward using Kodama's theory of spherically symmetric
gravitational fields. The theory also applies to point masses embedded in an
expanding universe, were the surface gravity is still related to Kodama-Hayward
theory. As a bonus of the tunneling method, we gain the insight that the
surface gravity still defines a temperature parameter as long as the evolution
is sufficiently slow that the black hole pass through a sequence of
quasi-equilibrium states.Comment: added references for section 1, corrected typos, some improvement in
notatio
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