2,958 research outputs found
Generalization of the model of Hawking radiation with modified high frequency dispersion relation
The Hawking radiation is one of the most interesting phenomena predicted by
the theory of quantum field in curved space. The origin of Hawking radiation is
closely related to the fact that a particle which marginally escapes from
collapsing into a black hole is observed at the future infinity with infinitely
large redshift. In other words, such a particle had a very high frequency when
it was near the event horizon. Motivated by the possibility that the property
of Hawking radiation may be altered by some unknowned physics which may exist
beyond some critical scale, Unruh proposed a model which has higher order
spatial derivative terms. In his model, the effects of unknown physics are
modeled so as to be suppressed for the waves with a wavelength much longer than
the critical scale, . Surprisingly, it was shown that the thermal
spectrum is recovered for such modified models. To introduce such higher order
spatial derivative terms, the Lorentz invariance must be violated because one
special spatial direction needs to be chosen. In previous works, the rest frame
of freely-falling observers was employed as this special reference frame. Here
we give an extension by allowing a more general choice of the reference frame.
Developing the method taken by Corley, % and especially focusing on subluminal
case, we show that the resulting spectrum of created particles again becomes
the thermal one at the Hawking temperature even if the choice of the reference
frame is generalized. Using the technique of the matched asymptotic expansion,
we also show that the correction to the thermal radiation stays of order
or smaller when the spectrum of radiated particle around its peak is
concerned.Comment: 23 pages, 5 postscript figures, submitted to Physical Review
A matrix model for a quantum hall droplet with manifest particle-hole symmetry
We find that a gauged matrix model of rectangular fermionic matrices (a
matrix version of the fermion harmonic oscillator) realizes a quantum hall
droplet with manifest particle-hole symmetry. The droplet consists of free
fermions on the topology of a sphere. It is also possible to deform the
Hamiltonian by double trace operators, and we argue that this device can
produce two body potentials which might lead the system to realize a fractional
quantum hall state on the sphere. We also argue that a single gauged fermionic
quantum mechanics of hermitian matrices realizes a droplet with an edge that
has CFT on it.Comment: 25 pages, uses JHEP format, young.sty (included). v2: Updated
references, typos correcte
Origin of the Thermal Radiation in a Solid-State Analog of a Black-Hole
An effective black-hole-like horizon occurs, for electromagnetic waves in
matter, at a surface of singular electric and magnetic permeabilities. In a
physical dispersive medium this horizon disappears for wave numbers with
. Nevertheless, it is shown that Hawking radiation is still emitted if
free field modes with are in their ground state.Comment: 13 Pages, 3 figures, Revtex with epsf macro
Black hole radiation with high frequency dispersion
We consider one model of a black hole radiation, in which the equation of
motion of a matter field is modified to cut off high frequency modes. The
spectrum in the model has already been analytically derived in low frequency
range, which has resulted in the Planckian distributin of the Hawking
temperature. On the other hand, it has been numerically shown that its spectrum
deviates from the thermal one in high frequency range. In this paper, we
analytically derive the form of the deviation in the high frequency range. Our
result can qualitatively explain the nature of the numerically calculated
spectrum. The origin of the deviation is clarified by a simple discussion.Comment: 9 pages, 10 figures, submitted to Phys.Rev.
Euclidean analysis of the entropy functional formalism
The attractor mechanism implies that the supersymmetric black hole near
horizon solution is defined only in terms of the conserved charges and is
therefore independent of asymptotic moduli. Starting only with the near horizon
geometry, Sen's entropy functional formalism computes the entropy of an extreme
black hole by means of a Legendre transformation where the electric fields are
defined as conjugated variables to the electric charges. However, traditional
Euclidean methods require the knowledge of the full geometry to compute the
black hole thermodynamic quantities. We establish the connection between the
entropy functional formalism and the standard Euclidean formalism taken at zero
temperature. We find that Sen's entropy function 'f' (on-shell) matches the
zero temperature limit of the Euclidean action. Moreover, Sen's near horizon
angular and electric fields agree with the chemical potentials that are defined
from the zero-temperature limit of the Euclidean formalism.Comment: 37 pages. v3: Footnote and Reference added. Published versio
- âŠ