4,947 research outputs found
Quasi-local charges and asymptotic symmetry generators
The quasi-local formulation of conserved charges through the off-shell
approach is extended to cover the asymptotic symmetry generators. By
introducing identically conserved currents which are appropriate for asymptotic
Killing vectors, we show that the asymptotic symmetry generators can be
understood as quasi-local charges. We also show that this construction is
completely consistent with the on-shell method.Comment: 19 pages; v2 typos fixe
Thermodynamic Volume and the Extended Smarr Relation
We continue to explore the scaling transformation in the reduced action
formalism of gravity models. As an extension of our construction, we consider
the extended forms of the Smarr relation for various black holes, adopting the
cosmological constant as the bulk pressure as in some literatures on black
holes. Firstly, by using the quasi-local formalism for charges, we show that,
in a general theory of gravity, the volume in the black hole thermodynamics
could be defined as the thermodynamic conjugate variable to the bulk pressure
in such a way that the first law can be extended consistently. This, so called,
thermodynamic volume can be expressed explicitly in terms of the metric and
field variables. Then, by using the scaling transformation allowed in the
reduced action formulation, we obtain the extended Smarr relation involving the
bulk pressure and the thermodynamic volume. In our approach, we do not resort
to Euler's homogeneous scaling of charges while incorporating the would-be
hairy contribution without any difficulty.Comment: 1+21 pages, plain LaTeX; v2 typo fixed and references adde
Modeling the GeV emission of HESS J0632+057
The binary system HESS J0632+057 was recently detected by {Fermi} to possess
orbital modulated GeV emission. In this paper, we study the possibility that
the compact companion of HESS J0632+057 is a pulsar. Under such a presumption,
we focus on the high energy emission mechanism of this system, which is as
follows. The pulsar companion travels through the circumstellar disc of the
main sequence star twice in each orbit, when some of the matter is
gravity-captured. The captured matter develops an accretion disc around the
pulsar, and the soft photons from which are inverse Compton scattered by the
pulsar wind as the GeV emission from the system. With proper choice of
parameters, SED and light curve which are in accordance with observations can
be produced. We predict that the light curve of GeV emission has two peaks, the
larger one is at around 0.4 after the periastron (or 0.1 after the X-ray
maximum), while the smaller one is between phases 0 and 0.1, with integrated
flux one forth of the larger one.Comment: 7pages, 7 figures. Accepted for publication in MNRA
Transparentizing Black Holes to Eternal Traversable Wormholes
We present the gravity description of evaporating black holes that end up
with eternal traversable wormholes where every would-be behind horizon degree
is available in asymptotic regions. The transition is explicitly realized by a
time-dependent bulk solution in the two-dimensional Einstein-dilaton gravity.
In this solution, the initial AdS black hole is evolved into an eternal
traversable wormhole free of any singularity, which may be dubbed as
transparentization of black holes to eternal traversable wormholes. The bulk
construction completely matches with the boundary description governed by the
Schwarzian boundary theory. We also obtain solutions describing eternal
traversable wormholes as well as excitations by an additional matter and
graviton oscillations on eternal traversable wormholes, which show that the
eternal traversable wormhole states are gapped and non-chaotic. Embedding the
2d solution into a 4d traversable wormhole connecting two magnetically charged
holes, we discuss 4d scattering of a wave incident upon one end of the
traversable wormhole.Comment: 1+34 pages, 5 figures, 4 tables; v2: various typos fixed, Ref. added;
v3: a few typos fixed, published versio
The first law of thermodynamics in Lifshitz black holes revisited
We obtain the mass expression of the three- and five-dimensional Lifshitz
black holes by em- ploying the recently proposed quasilocal formulation of
conserved charges, which is based on the off-shell extension of the ADT
formalism. Our result is consistent with the first law of black hole
thermodynamics and resolves the reported discrepancy between the ADT formalism
and the other conventional methods. The same mass expression of Lifshitz black
holes is obtained by using an- other quasilocal method by Padmanabhan. We also
discuss the reported discrepancy in the context of the extended first law of
black hole thermodynamics by allowing the pressure term.Comment: 16pages, improved version to appear in JHE
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