119423869
On Symplectic and Multisymplectic Srtuctures and their Discrete Versions in Lagrangian Formalism
We introduce the Euler-Lagrange cohomology to study the symplectic and multisymplectic structures and their preserving properties in finite and infinite dimensional Lagrangian systems respectively. We also explore their certain difference discrete counterparts in the relevant regularly discretized finite and infinite dimensional Lagrangian systems by means of the difference discrete variational principle with the difference being regarded as an entire geometric object and the noncommutative differential calculus on regular lattice. In order to show that in all these cases the symplectic and multisymplectic preserving properties do not necessarily depend on the relevant Euler-Lagrange equations, the Euler-Lagrange cohomological concepts and content in the configuration space are employed.
124820814
R-Matrices for Some Inhomogeneous Quantum Groups*
In this paper, some new generalized inhomogeneous quantum groups corresponding to the homogeneous multiparameter quantum groups are constructed, furthermore, the -matrices for these inhomogeneous quantum groups are found.
123950095
Global Solutions of Einstein–Dirac Equation on the Conformal Space*
The difference between the Riemann and Lorentz spinor manifolds of four dimensions is that the Dirac operator of the former is elliptic and that of the latter is hyperbolic. Moreover the spinor group of the former is a compact group and that of the latter is a noncompact group, which is isomorphic to SL(2,C). Hence the results and their interpretation coming from the two theories would be different. In this short note we study only the Lorentz spinor manifold and, especially, the solutions of Einstein-Dirac equations on the conformal space, which is closely related to the AdS/CFT correspondence.
123836451
ANOMALIES OF ARBITRARY GAUGE GROUP AND ITS REDUCTION GROUP, EINSTEIN AND LORENTZ ANOMALIES
Based upon the properties of the characteristic classes and their Chern-Simons secondary characteristic classes, the "Abelian" anomalies in , the Euler-Heisenberg effective actions in , as well as the non-Abelian anomalies in for arbitrary gauge group and its reduction subgroup have been investigated thoroughly and the application to the gravitational anomalies is made. It is shown that the "Abelian" anomalies of such groups are equal to each other, their Eu1er-Heisenberg actions are also closely related to each, other, and their non-Abelian anomalies are also equivalent if their common generating functional can be taken as a counter-term. For the gravitational anomalies we present the common generating functional for both non-Abelian Einstein and Lorentz anomalies in and show the relationship between them.
124010822
ASSOCIATIVITY OF REPRESENTATIONS AND COCYCLES OF GAUGE GROUPS
It is shown that the consistency of certain representations of group requires a mod Z-cocycle condition which leads to some topological quantization constants in corresponding anomalous algebraic relations, such as anomalous commutators and anomalous Jacobi identities. It should be pointed out that the mod Z-cocycles for gauge groups could be constructed by means of the generalized secondary characteristic classes.
119356933
Super-Yangian Y( gl(1|1)) and its oscillator realization
On the basis of graded RTT formalism, the defining relation of the super-Yangian is derived and its oscillator realization is constructed.
718692
Secular and orbital variability of Cir X-1 observed in optical spectra
ABSTRA C T We have observed variations in the optical emission lines from the X-ray binary Circinus X-1. These variations may be attributed both to orbital variations and to long term secular changes in line strength. We have detected double-peaked Ha emission lines on two occasions, providing the first direct evidence for an accretion disc in the system. The separation of the peaks was different on the two occasions, suggesting that the disc might have a different size. The equivalent width of the emission lines dropped by more than a factor of three between 1999 and 2000; this continues the trend seen in earlier data, so that the Ha equivalent width has now declined by a factor of 20 since 1976. The emission lines do not appear to show signature of orbital motion, except for the data taken near phase 0, which show a significant velocity shift. We have observed an absorption component to the He I lines on one occasion. We suggest that, unlike the P Cygni profiles seen in X-ray spectra, this absorption does not arise in the accelerating zone of a radiatively driven wind. Instead, the absorption arises in material previously ejected from the system. It was only seen on this one occasion because the strength of the emission line had dropped dramatically.
119422800
Optical Spectroscopy of GRO J1655–40
We have obtained optical spectra of the soft X-ray transient GRO J1655-40 during different X-ray spectral states (quiescence, high-soft, and hard outburst) between 1994 August and 1997 June. Characteristic features observed during the 1996-1997 high-soft state were: (1) broad absorption lines at Hα and Hβ, probably formed in the inner disk; (2) double-peaked He II λ4686 emission lines, formed in a temperature-inversion layer on the disk surface, created by the soft X-ray irradiation; and (3) double-peaked Hα emission, with a strength associated with the hard X-ray flux, suggesting that it was probably emitted from deeper layers than He II λ4686. The He II λ4686 line profile appeared approximately symmetric, as we would expect from a disk surface with an axisymmetric emissivity function. The Balmer emission, on the other hand, appeared to come only from a double-armed region on the disk, possibly the locations of tidal density waves or spiral shocks. The observed rotational velocities of all the double-peaked lines suggest that the disk was extended slightly beyond its tidal radius. Three classes of lines were identified in the spectra taken in 1994 August-September, during a period of low X-ray activity between two strong X-ray flares: broad absorption, broad (flat-topped) emission, and narrow emission. We have found that the narrow (single-peaked or double-peaked) emission lines cannot be explained by a conventional thin accretion disk model. We propose that the system was in a transient state, in which the accretion disk might have had an extended optically thin cocoon and significant matter outflow, which would also explain the systematic blueshift of the narrow emission lines and the flat-topped profiles of the broad emission lines. After the onset of a hard X-ray flare the disk signatures disappeared, and strong single-peaked Hα and Paschen emission was detected, suggesting that the cocoon became opaque to optical radiation. High-ionization lines disappeared or weakened. Two weeks after the end of the flare, the cocoon appeared to be once again optically thin.
14214237
Characteristic temperatures and spectral appearance of ULX disks
A standard disk around an accreting black hole may become effectively optically-thin and scattering dominated in the inner region, for high accretion rates (as already predicted by the Shakura-Sunyaev model). Radiative emission from that region is less efficient than blackbody emission, leading to an increase of the colour temperature in the inner region, by an order of magnitude above the effective temperature. We show that the integrated spectrum has a power-law-like shape in the ~ 1-5 keV band, with a soft excess at lower energies and a downward curvature or break at higher energies, in agreement with the observed spectra of many ultraluminous X-ray sources.
18595380
Radiative transfer in black hole systems
We present a convariant formulation for radiative transfer in curved space time and demonstrate some applications in the black-hole systems. We calculate the emission from semi-transparent accretion tori around black holes, for opacity provided by the Fe K lines and for opacity dominated by electron scattering. We also calculate the emission from radiative inefficient accretion flow in black holes with opacity provided by electron-positron annihilation lines. Finally we show shadows cast by accreting black holes with different spins and with different distribution of warm material around them.
119120924
On the Nature of Ultra-Luminous X-ray Sources from Optical/IR Measurements
We present a model for the prediction of the optical/infra-red emission from ULXs. In the model, ULXs are binary systems with accretion taking place through Roche lobe overflow. We show that irradiation effects and presence of an accretion disk significantly modify the optical/infrared flux compared to single stars, and also that the system orientation is important. We include additional constraints from the mass transfer rate to constrain the parameters of the donor star, and to a lesser extent the mass of the BH. We apply the model to fit photometric data for several ULX counterparts. We find that most donor stars are of spectral type B and are older and less massive than reported elsewhere, but that no late-type donors are admissible. The degeneracy of the acceptable parameter space will be significantly reduced with observations over a wider spectral range, and if time-resolved data become available.