8832899
Molecular line profiles of collapsing gas clouds
Emission-line profiles of the tracer molecule H 2 CO 140 GHz transition from gravitational core collapsing clouds in the dynamic process of forming protostars are calculated, using a simple ray-tracing radiative transfer model. Three self-similar dynamic inside-out core collapse models - the conventional polytropic model, the empirical hybrid model and the isothermal model - for star-forming molecular clouds are examined and compared. The isothermal model cannot produce observed asymmetric double-peak molecular line profiles. The conventional polytropic model, which gives flow velocity, mass density and temperature profiles self-consistently, can produce asymmetric double-peak line profiles for a core collapsing cloud. In particular, the blue peak is stronger than the red peak, consistent with a broad class of molecular line-profile observations. We find that line profiles are robust against variations in the polytropic index γ once the effective line-centre opacity K o is specified. The relative strengths of the blue and red peaks within a molecular line profile are determined by the cloud temperature gradient, but the emission at frequencies between the two line peaks is determined by detailed density and velocity profiles in the cloud core. In the presence of a static dense kernel at the centre of a collapsing cloud, strong internal absorption along the line of sight may occur, causing a suppression to the red wing of the blue line peak. If reliably resolved in frequency by observations, this signature may be potentially useful for probing the environs of an infant protostar. The conventional polytropic model can be utilized to produce molecular line-profile templates, for extracting dynamical information from line spectra of molecular globules undergoing a gravitational core collapse. We show a sample fit using the 140 GHz H 2 CO emission line from the central region of the molecular globule B335 by our model with γ = 1.2. The calculation of line profiles and fitting processes also offer a scenario to estimate the protostellar mass, the kernel mass accretion rate and the evolution time-scale of a core collapsing cloud. Our model can be readily adapted to other tracer molecules with more or less constant abundances in star-forming clouds.
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.
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.
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.
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.
124310548
DIFFERENTIAL-CALCULUS ON QUANTUM MATRIX LIE-GROUPS
Following the discussions on quantum groups by Reshetikhin, Takhadshyan and Faddeev, we thoroughly studied the differential calculus on quantum groups, and obtained the explicit expressione in the case of . We also compared our results with those of Woronowicz and Podles under the restriction of to .
15340222
Wilson--Yukawa Chiral Model on Lattice and Non-commutative Geometry
Based upon the mathematical formulas of Lattice gauge theory and non-commutative geometry differential calculus, we developed an approach of generalized gauge theory on a product of the spacetime lattice and the two discrete points(or a $Z_2$ discrete group). We introduce a differentiation for non-nearest-neighbour points and find that this differentiation may lead to the introduction of Wilson term in the free fermion Lagrangian on lattice. The Wilson-Yukawa chiral model on lattice is constructed by the generalized gauge theory and a toy model and Smit-Swift model are studied.
10717094
Two Particle Physics Models With Spontaneous CP Violation From Gauge Theory On Discrete Group
Based on the differential calculus and the gauge theory on discrete groups, we reconstruct two physics models with spontaneous CP violation: (1) The Georgi-Glashow-Lee model with two Higgs triplets; (2) The Weinberg-Salam-Branco model with three Higgs doublets and the natural flavor conservation (NFC). We focus on the Lagrangian terms containing the Higgs particles and show that with an appropriate choice of the discrete groups, we can obtain the physically meaningful Yukawa couplings and the Higgs potentials which lead to the spontaneous CP violation consequently.
8201962
The algebraic structure of the gl(n|m) color Calogero–Sutherland models
We extend the study on the algebraic structure of the su(n) color Calogero–Sutherland (CS) models to the case of gl(n|m) color CS model and show that the generators of the super-Yangian Y(gl(n|m)) can be obtained from two gl(n|m) loop algebras. Also, a super W∞ algebra for the SUSY CS model is constructed.
197519229
Gravity and Discrete Symmetry
Using the differential calculus on discrete group, we study the general relativity in the space-time which is the product of a four dimensional manifold by a two-point space. We generalize the usual concept of frame and connection in our space-time, and from the generalized torsion free condition we obtain an action of a scalar field coupled to Einstein gravity, which may be related to the Jordan-Brans-Dicke theory.