267 research outputs found
Discovery of a Probable Physical Triple Quasar
We report the discovery of the first known probable case of a physical triple
quasar (not a gravitational lens). A previously known double system, QQ
1429-008 at z = 2.076, is shown to contain a third, fainter QSO component at
the same redshift within the measurement errors. Deep optical and IR imaging at
the Keck and VLT telescopes has failed to reveal a plausible lensing galaxy
group or a cluster, and moreover, we are unable to construct any viable lensing
model which could lead to the observed distribution of source positions and
relative intensities of the three QSO image components. Furthermore, there are
hints of differences in broad-band spectral energy distributions of different
components, which are more naturally understood if they are physically distinct
AGN. Therefore, we conclude that this system is most likely a physical triple
quasar, the first such close QSO grouping known at any redshift. The projected
component separations in the restframe are ~ 30 - 50 kpc for the standard
concordance cosmology, typical of interacting galaxy systems. The existence of
this highly unusual system supports the standard picture in which galaxy
interactions lead to the onset of QSO activity.Comment: Submitted to ApJL, LaTeX, 13 pages, 4 eps figures, all include
Physics of Quantum Relativity through a Linear Realization
The idea of quantum relativity as a generalized, or rather deformed, version
of Einstein (special) relativity has been taking shape in recent years.
Following the perspective of deformations, while staying within the framework
of Lie algebra, we implement explicitly a simple linear realization of the
relativity symmetry, and explore systematically the resulting physical
interpretations. Some suggestions we make may sound radical, but are arguably
natural within the context of our formulation. Our work may provide a new
perspective on the subject matter, complementary to the previous approach(es),
and may lead to a better understanding of the physics.Comment: 27 pages in Revtex, no figure; proof-edited version to appear in
Phys.Rev.
Doubly Special Relativity and de Sitter space
In this paper we recall the construction of Doubly Special Relativity (DSR)
as a theory with energy-momentum space being the four dimensional de Sitter
space. Then the bases of the DSR theory can be understood as different
coordinate systems on this space. We investigate the emerging geometrical
picture of Doubly Special Relativity by presenting the basis independent
features of DSR that include the non-commutative structure of space-time and
the phase space algebra. Next we investigate the relation between our geometric
formulation and the one based on quantum -deformations of the
Poincar\'e algebra. Finally we re-derive the five-dimensional differential
calculus using the geometric method, and use it to write down the deformed
Klein-Gordon equation and to analyze its plane wave solutions.Comment: 26 pages, one formula (67) corrected; some remarks adde
Quantum Potential Approach to Class of Cosmological Models
In this paper we discuss the quantum potential approach of Bohm in the
context of quantum cosmological model. This approach makes it possible to
convert the wavefunction of the universe to a set of equations describing the
time evolution of the universe. Following Ashtekar et.\ al., we make use of
quantum canonical transformation to cast a class of quantum cosmological models
to a simple form in which they can be solved explicitly, and then we use the
solutions do recover the time evolution.Comment: The corrected version of gr-qc/9506081, 18 pages LaTeX, to appear in
Classical and Quantum Gravit
Kinematics of a relativistic particle with de Sitter momentum space
We discuss kinematical properties of a free relativistic particle with
deformed phase space in which momentum space is given by (a submanifold of) de
Sitter space. We provide a detailed derivation of the action, Hamiltonian
structure and equations of motion for such free particle. We study the action
of deformed relativistic symmetries on the phase space and derive explicit
formulas for the action of the deformed Poincare' group. Finally we provide a
discussion on parametrization of the particle worldlines stressing analogies
and differences with ordinary relativistic kinematics.Comment: RevTeX, 12 pages, no figure
de Sitter special relativity
A special relativity based on the de Sitter group is introduced, which is the
theory that might hold up in the presence of a non-vanishing cosmological
constant. Like ordinary special relativity, it retains the quotient character
of spacetime, and a notion of homogeneity. As a consequence, the underlying
spacetime will be a de Sitter spacetime, whose associated kinematics will
differ from that of ordinary special relativity. The corresponding modified
notions of energy and momentum are obtained, and the exact relationship between
them, which is invariant under a re-scaling of the involved quantities,
explicitly exhibited. Since the de Sitter group can be considered a particular
deformation of the Poincar\'e group, this theory turns out to be a specific
kind of deformed (or doubly) special relativity. Some experimental
consequences, as well as the causal structure of spacetime--modified by the
presence of the de Sitter horizon--are briefly discussed.Comment: V2: Some presentation changes; a new section introduced, with a
discussion about possible phenomenological consequences; new references
added; version to be published in Classical and Quantum Gravit
Lorentz-covariant deformed algebra with minimal length
The -dimensional two-parameter deformed algebra with minimal length
introduced by Kempf is generalized to a Lorentz-covariant algebra describing a
()-dimensional quantized space-time. For D=3, it includes Snyder algebra
as a special case. The deformed Poincar\'e transformations leaving the algebra
invariant are identified. Uncertainty relations are studied. In the case of D=1
and one nonvanishing parameter, the bound-state energy spectrum and
wavefunctions of the Dirac oscillator are exactly obtained.Comment: 8 pages, no figure, presented at XV International Colloquium on
Integrable Systems and Quantum Symmetries (ISQS-15), Prague, June 15-17, 200
Harmonic BRST Quantization of Systems with Irreducible Holomorphic Boson and Fermion Constraints
We show that the harmonic Becchi-Rouet-Stora-Tyutin method of quantizing
bosonic systems with second-class constraints or first-class holomorphic
constraints extends to systems having both bosonic and fermionic second-class
or first-class holomorphic constraints. Using a limit argument, we show that
the harmonic BRST modified path integral reproduces the correct Senjanovic
measure.Comment: 11 pages, phyzz
Three-body equations of motion in successive post-Newtonian approximations
There are periodic solutions to the equal-mass three-body (and N-body)
problem in Newtonian gravity. The figure-eight solution is one of them. In this
paper, we discuss its solution in the first and second post-Newtonian
approximations to General Relativity. To do so we derive the canonical
equations of motion in the ADM gauge from the three-body Hamiltonian. We then
integrate those equations numerically, showing that quantities such as the
energy, linear and angular momenta are conserved down to numerical error. We
also study the scaling of the initial parameters with the physical size of the
triple system. In this way we can assess when general relativistic results are
important and we determine that this occur for distances of the order of 100M,
with M the total mass of the system. For distances much closer than those,
presumably the system would completely collapse due to gravitational radiation.
This sets up a natural cut-off to Newtonian N-body simulations. The method can
also be used to dynamically provide initial parameters for subsequent full
nonlinear numerical simulations.Comment: 8 pages, 9 figure
Background gauge invariance in the antifield formalism for theories with open gauge algebras
We show that any BRST invariant quantum action with open or closed gauge
algebra has a corresponding local background gauge invariance. If the BRST
symmetry is anomalous, but the anomaly can be removed in the antifield
formalism, then the effective action possesses a local background gauge
invariance. The presence of antifields (BRST sources) is necessary. As an
example we analyze chiral gravity.Comment: 17pp., Latex, mispelling in my name! corrected, no other change
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