Subleading contributions to the black hole entropy in the brick wall approach
Sudipta Sarkar, S. Shankaranarayanan, and L. Sriramkumar
The brick wall model is a semiclassical approach to understand the microscopic origin of black hole entropy. In this approach, the black hole geometry is assumed to be a fixed classical background on which matter fields propagate, and the entropy of black holes supposedly arises due to the canonical ... [Phys. Rev. D 78, 024003 (2008)] published Thu Jul 3, 2008.
Unique factor ordering in the continuum limit of loop quantum cosmology
William Nelson and Mairi Sakellariadou
We show that the factor ordering ambiguities associated with the loop quantization of the gravitational part of the cosmological Hamiltonian constraint disappear at the level of the Wheeler-DeWitt equation only for a particular choice of lattice refinement model, which coincides with constraints imp ... [Phys. Rev. D 78, 024006 (2008)] published Thu Jul 3, 2008.
Intuitive understanding of non-Gaussianity in ekpyrotic and cyclic models
Jean-Luc Lehners and Paul J. Steinhardt
It has been pointed out by several groups that ekpyrotic and cyclic models generate significant non-Gaussianity. In this paper, we present a physically intuitive, semianalytic estimate of the bispectrum. We show that, in all such models, there is an intrinsic contribution to the non-Gaussianity para ... [Phys. Rev. D 78, 023506 (2008)] published Thu Jul 3, 2008.
Bayesian approach to the follow-up of candidate gravitational wave signals
J. Veitch and A. Vecchio
Ground-based gravitational wave laser interferometers (LIGO, GEO-600, Virgo, and Tama-300) have now reached high sensitivity and duty cycle. We present a Bayesian evidence-based approach to the search for gravitational waves, in particular aimed at the follow-up of candidate events generated by the ... [Phys. Rev. D 78, 022001 (2008)] published Thu Jul 3, 2008.
Quasinormal modes of brane-localized standard model fields in Gauss-Bonnet theory
A. Zhidenko
We study the massless scalar, Dirac, and electromagnetic fields propagating on a 4D-brane, which is embedded in higher-dimensional Gauss-Bonnet space-time. We calculate, in the time domain, the fundamental quasinormal modes of a spherically symmetric black hole for such fields. Using WKB approximati ... [Phys. Rev. D 78, 024007 (2008)] published Thu Jul 3, 2008.
Effective one body approach to the dynamics of two spinning black holes with next-to-leading order spin-orbit coupling
Thibault Damour, Piotr Jaranowski, and Gerhard Schafer
Using a recent, novel Hamiltonian formulation of the gravitational interaction of spinning binaries, we extend the effective one body (EOB) description of the dynamics of two spinning black holes to next-to-leading order (NLO) in the spin-orbit interaction. The spin-dependent EOB Hamiltonian is cons ... [Phys. Rev. D 78, 024009 (2008)] published Thu Jul 3, 2008.
Does the mass of a black hole decrease due to the accretion of phantom energy?
Changjun Gao, Xuelei Chen, Valerio Faraoni, and You-Gen Shen
According to Babichev et al., the accretion of a phantom test fluid onto a Schwarzschild black hole will induce the mass of the black hole to decrease, however the backreaction was ignored in their calculation. Using new exact solutions describing black holes in a background Friedmann-Robertson-Walk ... [Phys. Rev. D 78, 024008 (2008)] published Thu Jul 3, 2008.
Can quantum gravitational effects influence the entire history of the Universe?
Edesio M. Barboza, Jr. and Nivaldo A. Lemos
In this work, a flat Friedmann-Robertson-Walker universe with dust and a cosmological constant is quantized. By means of a canonical transformation, the classical Hamiltonian is reduced to that of either a harmonic oscillator or anti-oscillator, depending on whether Lambda<0 or Lambda>0, respectivel ... [Phys. Rev. D 78, 023504 (2008)] published Thu Jul 3, 2008.
Static and symmetric wormholes respecting energy conditions in Einstein-Gauss-Bonnet gravity
Hideki Maeda and Masato Nozawa
Properties of n(>=5)-dimensional static wormhole solutions are investigated in Einstein-Gauss-Bonnet gravity with or without a cosmological constant Lambda. We assume that the spacetime has symmetries corresponding to the isometries of an (n-2)-dimensional maximally symmetric space with the sectiona ... [Phys. Rev. D 78, 024005 (2008)] published Thu Jul 3, 2008.
From Rindler space to the electromagnetic energy-momentum tensor of a Casimir apparatus in a weak gravitational field
Giuseppe Bimonte, Giampiero Esposito, and Luigi Rosa
This paper studies two perfectly conducting parallel plates in the weak gravitational field on the surface of the Earth. Since the appropriate line element, to first order in the constant gravity acceleration g, is precisely of the Rindler type, we can exploit the formalism for studying Feynman Gree ... [Phys. Rev. D 78, 024010 (2008)] published Thu Jul 3, 2008.
Extended monopole solution of the Blandford-Znajek mechanism: Higher order terms for a Kerr parameter
Kentarou Tanabe and Shigehiro Nagataki
The Blandford-Znajek mechanism, by which the rotational energy of a black hole is extracted through electromagnetic fields, is one of the promising candidates as an essential process of the central engine of active compact objects such as gamma-ray bursts. The only known analytical solution of this ... [Phys. Rev. D 78, 024004 (2008)] published Thu Jul 3, 2008.
Mixed hyperbolic---second-order-parabolic formulations of general relativity
Vasileios Paschalidis
Two new formulations of general relativity are introduced. The first one is a parabolization of the Arnowitt-Deser-Misner formulation and is derived by the addition of combinations of the constraints and their derivatives to the right-hand side of the Arnowitt-Deser-Misner evolution equations. The d ... [Phys. Rev. D 78, 024002 (2008)] published Thu Jul 3, 2008.
Is a dissipative regime during inflation in agreement with observations?
Alessandro Cerioni, Fabio Finelli, and Alessandro Gruppuso
We study the spectral index of curvature perturbations for inflationary models where the driving scalar field is coupled to a relativistic fluid through a friction term Gamma. In the regime in which Gamma can be at most as large as H, the Hubble parameter during inflation, we find that only Gamma<
A General Test of the Copernican Principle
Chris Clarkson, Bruce Bassett, and Teresa Hui-Ching Lu
To date, there has been no general way of determining if the Copernican principlethat we live at a typical position in the Universeis in fact a valid assumption, significantly weakening the foundations of cosmology as a scientific endeavor. Here we present an observational test for the Copernican as ... [Phys. Rev. Lett. 101, 011301 (2008)] published Wed Jul 2, 2008.
Static charged fluid around a magnetized mass
I. Cabrera-Munguia and V. S. Manko
We show that any magnetostatic axially symmetric solution of the Einstein-Maxwell equations can be endowed with a specific charged fluid source of the Polanco et al. type via a simple procedure requiring the knowledge of exclusively the magnetostatic seed spacetime. Using this procedure we construct ... [Phys. Rev. D 78, 024001 (2008)] published Wed Jul 2, 2008.
Cosmic string Y-junctions: A comparison between field theoretic and Nambu-Goto dynamics
Neil Bevis and Paul M. Saffin
We explore the formation of cosmic string Y-junctions when strings of two different types collide, which has recently become important since string theory can yield cosmic strings of distinct types. Using a model containing two types of local U(1) string and stable composites, we simulate the collis ... [Phys. Rev. D 78, 023503 (2008)] published Wed Jul 2, 2008.
Einstein-Cartan formulation of Chern-Simons Lorentz-violating gravity
Marcelo Botta Cantcheff
We consider a modification of the standard Einstein theory in four dimensions, alternative to R. Jackiw and S.-Y. Pi, Phys. Rev. D 68, 104012 (2003), since it is based on the first-order (Einstein-Cartan) approach to general relativity, whose gauge structure is manifest. This is done by introducing ... [Phys. Rev. D 78, 025002 (2008)] published Wed Jul 2, 2008.
Cosmic string dynamics and evolution in warped spacetime
A. Avgoustidis
We study the dynamics and evolution of Nambu-Goto strings in a warped spacetime, where the warp factor is a function of the internal coordinates giving rise to a throat region. The microscopic equations of motion for strings in this background include potential and friction terms, which attract the ... [Phys. Rev. D 78, 023501 (2008)] published Tue Jul 1, 2008.
One Loop Superstring Effective Actions and d = 4 Supergravity
Filipe Moura
We review our recent work on the existence of a new independent R term, at one loop, in the type IIA and heterotic effective actions, after reduction to four dimensions, besides the usual square of the Bel-Robinson tensor. We discuss its supersymmetrization. ... [AIP Conf. Proc. 1023, 192 (2008)] published Mon Jun 30, 2008.
The Principle of General Tovariance
C. Heunen, N. P. Landsman, and B. Spitters
We tentatively propose two guiding principles for the construction of theories of physics, which should be satisfied by a possible future theory of quantum gravity. These principles are inspired by those that led Einstein to his theory of general relativity, viz. his principle of general covariance ... [AIP Conf. Proc. 1023, 93 (2008)] published Mon Jun 30, 2008.
Some Geometrical Aspects of M-Theory
Jose A. de Azcarraga and Jose M. Izquierdo
Some geometrical aspects of super-p-brane theory, M-theory, and their connection with supergravity, are reviewed. In particular, the different fractions of preserved supersymmetries are discussed both from the algebraic and the supergravity solutions point of view. We also review the `preon conjectu ... [AIP Conf. Proc. 1023, 57 (2008)] published Mon Jun 30, 2008.
Quantum Geometry and Quantum Gravity
J. Fernando Barbero G.
The purpose of this contribution is to give an introduction to quantum geometry and loop quantum gravity for a wide audience of both physicists and mathematicians. From a physical point of view the emphasis will be on conceptual issues concerning the relationship of the formalism with other more tra ... [AIP Conf. Proc. 1023, 3 (2008)] published Mon Jun 30, 2008.
Zero-size objects in Riemann-Cartan spacetime. (arXiv:0807.0596v1 [gr-qc])
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Basic quantum mechanics for three Dirac equations in a curved spacetime. (arXiv:0807.0570v1 [gr-qc])
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Effect of a positive cosmological constant on cosmic strings. (arXiv:0807.0543v1 [gr-qc])
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What kinds of coordinate can keep the Hawking temperature invariant for the static spherically symmetric black hole?. (arXiv:0807.0477v1 [gr-qc])
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Ultra-hard fluid and scalar field in the Kerr-Newman metric. (arXiv:0807.0449v1 [gr-qc])
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Homogeneous and Isotropic Born-Infeld Cosmologies. (arXiv:0807.0448v1 [gr-qc])
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Implications of the graviton one-loop effective action on the dynamics of the Universe. (arXiv:0807.0447v1 [gr-qc])
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Graviton one-loop effective action and inflationary dynamics. (arXiv:0807.0439v1 [gr-qc])
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Gravitational Geons in 1+1 Dimensions. (arXiv:0807.0611v1 [gr-qc])
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Relativistic cosmology and large-scale structure. (arXiv:0705.4397v3 [astro-ph] UPDATED)
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Advances in the measurement of the Lense-Thirring effect with planetary motions in the field of the Sun. (arXiv:0807.0435v3 [gr-qc] UPDATED)
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Transition Redshift: New Kinematic Constraints from Supernovae. (arXiv:0805.1261v2 [astro-ph] UPDATED)
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Newtonian nonlinear hydrodynamics and magnetohydrodynamics. (arXiv:0804.1702v3 [astro-ph] UPDATED)
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Subtraction-noise projection in gravitational-wave detector networks. (arXiv:0803.0226v2 [gr-qc] UPDATED)
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Matching WMAP 3-yrs results with the Cosmological Slingshot Primordial Spectrum. (arXiv:0706.0025v3 [astro-ph] UPDATED)
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Strong lensing in the Einstein-Straus solution. (arXiv:0807.0380v1 [astro-ph] CROSS LISTED)
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A Mathematical Theory of Stochastic Microlensing I. Random Time-Delay Functions and Lensing Maps. (arXiv:0807.0232v1 [astro-ph] CROSS LISTED)
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Quantum gravity as a Fermi liquid. (arXiv:0807.0225v1 [hep-th] CROSS LISTED)
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Tidal Disruption Flares from Recoiling Supermassive Black Holes. (arXiv:0807.0223v1 [astro-ph] CROSS LISTED)
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