17351565
Effects of gravity on the structure of post-shock accretion flows in magnetic cataclysmic variables
We calculate the temperature and density structure of the hot post-shock plasma in magnetically confined accretion flows, including the gravitational potential. This avoids the inconsistency of previous calculations which assume that the height of the shock is negligible. We assume a stratified accretion column with 1D flow along the symmetry axis. We find that the calculations predict a lower shock temperature than previous calculations, with a flatter temperature profile with height. We revise previous determinations of the masses of the white dwarf primary stars, and find that for higher mass white dwarfs there is a general reduction in derived masses when the gravitational potential is included. This is because the spectrum from such flows is harder than that of previous prescriptions at intermediate energies.
1734663
Line emission from optically thick relativistic accretion tori
We calculate line emission from relativistic accretion tori around Kerr black holes and investigate how the line profiles depend on the viewing inclination, spin of the central black hole, parameters describing the shape of the tori, and spatial distribution of line emissivity on the torus surface. We also compare the lines with those from thin accretion disks. Our calculations show that lines from tori and lines from thin disks share several common features. In particular, at low and moderate viewing inclination angles they both have asymmetric double-peaked profiles with a tall, sharp blue peak and a shorter red peak which has an extensive red wing. At high viewing inclination angles they both have very broad, asymmetric lines which can be roughly considered as single-peaked. Torus and disk lines may show very different red and blue line wings, but the differences are due to the models for relativistic tori and disks having differing inner boundary radii. Self-eclipse and lensing play some role in shaping the torus lines, but they are effective only at high inclination angles. If inner and outer radii of an accretion torus are the same as those of an accretion disk, their line profiles show substantial differences only when inclination angles are close to 90°, and those differences manifest mostly at the central regions of the lines instead of the wings.
18756154
Formation of optical lines in black-hole binaries
The HI Balmer emission lines of black-hole binaries show double-peaked profiles during the high-soft state and the quiescent state. In the high-soft state the profiles are asymmetric with a stronger red peak, but the profiles are symmetric in the quiescent state. We suggest that in the high-soft state the emission lines originate from the temperature-inversion layer caused by irradiative heating of an optically thick accretion disk. Irradiative heating also causes the formation of a disk wind, which mildly absorbs the blue peak of the lines. The double-peaked lines seen in the quiescent state arise from an optically thin disk. In the absence of a disk wind, the lines are unabsorbed and so the symmetry of the line profiles is preserved.
14186187
Accretion Flow along a Dipolar Field: Application to Intermediate Polars
A hydrodynamic formulation for accretion flow channeled by a dipolar magnetic field is constructed using a curvi-linear coordinate system natural to the field structure. We solve the hydrodynamic equations and determine the velocity, density and temperature profiles of the post-shock accretion flow. The results are applied to accretion flows in intermediate polars. We have found that for systems with massive white dwarfs (~ 1 M ⊙ ) the temperature profiles in the flow can differ significantly to those obtained from models in which the accretion column is assumed to be cylindrical.
13854637
Ionization structure in accretion shocks with a composite cooling function
ABSTRA C T We have investigated the ionization structure of the post-shock regions of magnetic cataclysmic variables, using an analytic density and temperature structure model in which effects caused by bremsstrahlung and cyclotron cooling are considered. We find that in the majority of the shock-heated region where H- and He-like lines of the heavy elements are emitted, the collisional-ionization and corona-condition approximations are justified. We have calculated the line emissivity and ionization profiles for iron as a function of height within the post-shock flow. For low-mass white dwarfs, line emission takes place near the shock. For high-mass white dwarfs, most of the line emission takes place in regions well below the shock and hence it is less sensitive to the shock temperature. Thus, the line ratios are useful to determine the white dwarf masses for the low-mass white dwarfs, but the method is less reliable when the white dwarfs are massive. Line spectra can, however, be used to map the hydrodynamic structure of the post-shock accretion flow.
119332271
Low and High Angular Momentum Accretion Flows in BHCs: Case Study of XTE J1550-564
The 1998 outburst of XTE J1550-564 started with a hard X-ray spike, rising in less than a day and declining after 3-4 days; at the same time, the soft X-ray flux was rising with a longer timescale (~ 10 days). We suggest that the soft and the initial hard X-ray emission are produced by two different components of the accretion flow: a higher angular momentum flow, which forms the disk, and a lower angular momentum flow feeding the hot inner region. Thus, we argue that the onset of the outburst is determined by an increased mass transfer rate from the companion star, but the outburst morphology is also determined by the distribution of specific angular momentum in the accreting matter. In XTE J1550-564, we attribute the initial, impulsive low angular momentum accretion to the breaking down of magnetic confinement by the magnetically active secondary star. We show that a hard X-ray spike is seen at the onset of an outburst in other BHCs.
115770555
Symmetries and solutions of colored Yang-Baxter equation for six vertex model
119781535
Holomorphic geometry of interacting strings
Abstract We apply the geometric quantization of Bowick and Rajeev to interacting bosonic strings. We calculate the total curvature of the two bundles over Diff S 1 /S 1 . The requirement of vanishing of the total curvature leads not only to the critical dimension d =26, but also to constraint equations for vertex operators. We find two solutions to these equations for external scalar fields which are interacting with the open string. Other interactions with a vector field, a weak gravitational field and so on are also discussed.
5363796
DEX: Increasing the Capability of Scientific Data Analysis Pipelines by Using Efficient Bitmap Indices to Accelerate Scientific Visualization
We describe a new approach to scalable data analysis that enables scientists to manage the explosion in size and complexity of scientific data produced by experiments and simulations. Our approach uses a novel combination of efficient query technology and visualization infrastructure. The combination of bit map indexing, which is a data management technology that accelerates queries on large scientific datasets, with a visualization pipeline for generating images of abstract data results in a tool suitable for use by scientists in fields where data size and complexity poses a barrier to efficient analysis. Our architecture and implementation, which we call DEX (short for dexterous data explorer), directly addresses the problem of ''too much data'' by focusing analysis on data deemed to be ''scientifically interesting'' via a user-specified selection criteria. The architectural concepts and implementation are applicable to wide variety of scientific data analysis and visualization applications. This paper presents an architectural overview of the system along with an analysis showing substantial performance over traditional visualization pipelines. While performance gains are a significant result, even more important is the new functionality not present in any visualization analysis software--namely the ability to perform interactive, multi-dimensional queries to refine regions of interest that aremore » later used as input to analysis or visualization.« less
122884461
On the composition laws of Beltrami-Liouville theories and 2D quantum gravity☆
Abstract We present the composition laws or cocycle conditions of the Liouville theory and Beltrami-Liouville theory as well as the quantum gravity in two dimensions. We show that for the 2D gravity, their special cases give rise to the composition laws of Polyakov's light-cone action and that of the geometric action of the Virasoro group. By means of the composition laws, we give the gravitational Ward identities and a relation between the actions of the Liouville theory and the topological gravity and find that the principal action of the 2D topological gravity is a coboundary which should obey a cocylce condition in the Liouville complex.
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.