264 research outputs found
On the "Universal" Quantum Area Spectrum
There has been much debate over the form of the quantum area spectrum for a
black hole horizon, with the evenly spaced conception of Bekenstein having
featured prominently in the discourse. In this letter, we refine a very
recently proposed method for calibrating the Bekenstein form of the spectrum.
Our refined treatment predicts, as did its predecessor, a uniform spacing
between adjacent spectral levels of in Planck units; notably, an outcome
that already has a pedigree as a proposed ``universal'' value for this
intrinsically quantum-gravitational measure. Although the two approaches are
somewhat similar in logic and quite agreeable in outcome, we argue that our
version is conceptually more elegant and formally simpler than its precursor.
Moreover, our rendition is able to circumvent a couple of previously unnoticed
technical issues and, as an added bonus, translates to generic theories of
gravity in a very direct manner.Comment: 7 Pages; (v2) now 9 full pages, significant changes to the text and
material added but the general theme and conclusions are unchange
Gravitational anomalies: a recipe for Hawking radiation
We explore the method of Robinson and Wilczek for deriving the Hawking
temperature of a black hole. In this method, the Hawking radiation restores
general covariance in an effective theory of near-horizon physics which
otherwise exhibits a gravitational anomaly at the quantum level. The method has
been shown to work for broad classes of black holes in arbitrary spacetime
dimensions. These include static black holes, accreting or evaporating black
holes, charged black holes, rotating black holes, and even black rings. In the
case of charged and rotating black holes, the expected super-radiant current is
also reproduced.Comment: 7 pages; This essay received an "Honorable Mention" in the 2007 Essay
Competition of the Gravity Research Foundation; (v2) Short comments and
references added; (v3) Minor revisions and updated references to agree with
published versio
Massive uncharged and charged particles' tunneling from the Horowitz-Strominger Dilaton black hole
Originally, Parikh and Wilczek's work is only suitable for the massless
particles' tunneling. But their work has been further extended to the cases of
massive uncharged and charged particles' tunneling recently. In this paper, as
a particular black hole solution, we apply this extended method to reconsider
the tunneling effect of the H.S Dilaton black hole. We investigate the behavior
of both massive uncharged and charged particles, and respectively calculate the
emission rate at the event horizon. Our result shows that their emission rates
are also consistent with the unitary theory. Moreover, comparing with the case
of massless particles' tunneling, we find that this conclusion is independent
of the kind of particles. And it is probably caused by the underlying
relationship between this method and the laws of black hole thermodynamics.Comment: 6 pages, no figure, revtex 4, accepted by Int. J. Mod. Phys
Tunnelling, Temperature and Taub-NUT Black Holes
We investigate quantum tunnelling methods for calculating black hole
temperature, specifically the null geodesic method of Parikh and Wilczek and
the Hamilton-Jacobi Ansatz method of Angheben et al. We consider application of
these methods to a broad class of spacetimes with event horizons, inlcuding
Rindler and non-static spacetimes such as Kerr-Newman and Taub-NUT. We obtain a
general form for the temperature of Taub-NUT-Ads black holes that is
commensurate with other methods. We examine the limitations of these methods
for extremal black holes, taking the extremal Reissner-Nordstrom spacetime as a
case in point.Comment: 22 pages, 3 figures; added references, fixed figures, added comments
to extremal section, added footnot
Hawking Radiation for Scalar and Dirac Fields in Five Dimensional Dilatonic Black Hole via Anomalies
We study massive scalar fields and Dirac fields propagating in a five
dimensional dilatonic black hole background. We expose that for both fields the
physics can be describe by a two dimensional theory, near the horizon. Then, in
this limit, by applying the covariant anomalies method we find the Hawking flux
by restoring the gauge invariance and the general coordinate covariance, which
coincides with the flux obtained from integrating the Planck distribution for
fermions.Comment: 10 page
On the energy of charged black holes in generalized dilaton-axion gravity
In this paper we calculate the energy distribution of some charged black
holes in generalized dilaton-axion gravity. The solutions correspond to charged
black holes arising in a Kalb-Ramond-dilaton background and some existing
non-rotating black hole solutions are recovered in special cases. We focus our
study to asymptotically flat and asymptotically non-flat types of solutions and
resort for this purpose to the M{\o}ller prescription. Various aspects of
energy are also analyzed.Comment: LaTe
Anomalies and Hawking radiation from the Reissner-Nordstr\"om black hole with a global monopole
We extend the work by S. Iso, H. Umetsu and F. Wilczek [Phys. Rev. Lett. 96
(2006) 151302] to derive the Hawking flux via gauge and gravitational anomalies
of a most general two-dimensional non-extremal black hole space-time with the
determinant of its diagonal metric differing from the unity () and use it to investigate Hawking radiation from the Reissner-Nordstrom
black hole with a global monopole by requiring the cancellation of anomalies at
the horizon. It is shown that the compensating energy momentum and gauge fluxes
required to cancel gravitational and gauge anomalies at the horizon are
precisely equivalent to the -dimensional thermal fluxes associated with
Hawking radiation emanating from the horizon at the Hawking temperature. These
fluxes are universally determined by the value of anomalies at the horizon.Comment: 18 pages, 0 figure. 1 footnote and 4 new reference adde
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