类星体的厚吸积盘与自引力吸积盘模型

本文对类星体的各种厚吸积盘模型,紫外超现象的吸积盘模型及自引力吸积盘模型作了简扼评述.     

类星体的有磁厚吸积盘模型

本文讨论了具有磁场的几何厚吸积盘结构和辐射。结果表明:磁场的存在明显地影响吸积盘的总光度和形状。这种模型可以解释类星体的辐射幂谱分布和高度偏振现象。它是类星体主要辐射区域的一种合理模型。     

含平流双温吸积盘的振荡不稳定性研究

从流体动力学方程出发,用微扰法得出含平流双温吸积盘的径向,环向不稳定性的色散方程,并对平流和径向粘滞力对双温吸积盘的影响进行了较详细的讨论。结果表明：平流和径向粘滞力对声模有较大的影响,且不改变粘滞模和热模的稳定性质。而环向扰动对吸积盘的各种模有着较明显的作用,这一模型有利于解释活动天体的周期和准周期光变现象。     

含粘滞和磁场的薄吸积盘不稳定性

本文采用微扰方法导出色散方程，并在四种情况下详细讨论了薄吸积盘的不稳定性，结果表明：在纯粘滞和纯磁场盘中存在脉动不稳定性，而且在吸积盘内同时考虑粘滞和磁场时，存在两稳定性，一种是脉动不稳定性，另一种是单调不稳定性，同时数值计算否定有明，脉动不稳定性更可能存在于内区，而财不稳定性则只在盘的外区，对短波扰动才有意义，这些结果为解释ＢＬ Ｌａｃ天体、Ｓｅｙｆｅｒｔ星系及星体活动星系核的光变现象进一步提供     

具有类偶极磁场的厚吸积盘模型

本文从磁流体力学基本方程组出发,讨论了具有类偶极磁场的厚吸积盘模型。其结果表明:引入这种磁场位形后,会影响盘的位形、光度和吸积率。对光度的影响是通过改变盘的位形实现的,它使盘变厚,会在厚盘的内区形成更窄更陡的漏斗状结构,这对解释类星体的高度准直性的喷流更为有利;并且还预言不对称喷流或单边喷流的存在。     

含粘滞和磁场的薄吸积盘不稳定性

本文采用微扰方法导出色散方程，并在四种情况下详细讨论了薄吸积盘的不稳定性。结果表明：在纯粘滞和纯磁场盘中都存在脉动不稳定性。而且在吸积盘内同时考虑粘滞和磁场时，存在两种不稳定性，一种是脉动不稳定性，另一种是单调不稳定性。同时数值计算还表明，脉动不稳定性更可能存在于盘的内区，而单调不稳定性则只在盘的外区，对短波扰动才有意义。这些结果为解释ＢＬＬａｃ天体、Ｓｅｙｆｅｒｔ星系及类星体等活动星系核的光变现象进一步提供了理论依据。     

黑洞吸积理论的新进展（Ⅱ）：含激波的吸积理论

着重评述了含激波吸积理论的发展历史和研究现状,介绍了在伪牛顿势以及严格广义和相论框架下,对等温和绝热两种不贩流体模型中可能发生的Ｒ－Ｈ激波,等温激波等各种不同激波的解析和数值模拟研究,包括激波发生的参数空间,不同流体参数下激波发生的位置,强度以和的能量。     

有吸积盘时径向运动云的谱线轮廓

在活动星系核的黑洞模型中,黑洞附近运动的电离云所发出的光线将要受到多普勒频移、引力红移和光线偏折等效应的影响,如果黑洞周围还有吸积盘存在,电离云的辐射还可能被吸积盘遮挡。本文全面地考虑了这些效应,利用光子输运方程方法,给出了在Schwarzchild度规中径向运动电离云发出的谱线轮廓的精确解,并发现在某些情况下将出现不对称的双峰结构。     

The Radial-Azimuthal Instability of Gas-Pressure-Dominated Accretion Disk with Advection

The radial-azimuthal instability of gas-pressure-dominated accretion disk with advection is examined in this paper. We find that the including of very little advection has significant effects on two acoustic modes, which are no longer complex conjugates of each other. They increase the instability of the O-mode and damp that of the I-mode. We also find that when the azimuthal perturbations are considered, the stability properties of disk are different from that in pure radial perturbation case. The increase of azimuthal wave number will stabilize the acoustic modes but make the viscous mode more unstable and does not change the thermal mode very much for optically thin disk. The I-mode is more stable. The O-mode, viscous mode and thermal mode tend to become more unstable with the increase of azimuthal perturbation wavenumber for optically thick disk. For a geometrically slim, advection-dominated disk, the increasing of azimuthal perturbations make thermal mode more unstable and acoustic mode more stable. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Two—Temperature Supernova Fallback Disk Model for Anomalous X—ray Pulsars

We present a case study of the relevance of the radially pulsational instability of a two-temperature accretion disk around a neutron star to anomalous X-ray pulsars (AXPs). Our estimates are based on the approximation that such a neutron star disk with mass in the range of 10^-6-10^-5M⊙ is formed by supernova fallback. We derive several peculiar properties of the accretion disk instability: a narrow interval of X-ray pulse periods; lower X-ray luminosities; a period derivative and an evolution time scale. All these results are in good agreement with the observations of the AXPs.     

The Supercritical Accretion Disk of SS 433

The structure of the SS 433 supercritical accretion disk derived from spectral and photometric data is described. In the disk plane, gas outflows at a velocity of about 100-150 km/s, while above the disk plane, the velocity increases sharply and reaches 1500 km/s at polar angle 60°. The outer parts of the accretion disk are involved in the precessional motion, which means that the slaved disk precession model is correct. There is complex periodic variability in the radial velocities of SS 433. Apart from the well-known precessional and orbital variability, the strongest cycle is 1/7 of the precession period, P7 = 23.228 ± 0.005 days. This is interpreted as evidence for a spiral shock in the accretion disk. The He II 4686 line consists of two components: a stream-formed narrow Gaussian profile and a broad double-peaked one. The latter is completely eclipsed at phase 0.0. Its blue and red peaks are probably emitted in gaseous cocoons around the bases of the relativistic jets. A correct value of the mass function has been found, which shows that the optical star is massive. The relativistic star's mass is estimated to be Mx 6M.     

吸积盘物理:稳定性和振动

研究了环绕致密天体的吸积盘的稳定性质和振动模式。特别关注了在热致和粘滞扰动作用下稳定的对流起支配作用的盘外流。还研究了相对论性吸积盘的振动模式。一些在盘内的捕获的 ,非衰减的模式也许可以用来解释X射线双星和活动星系核中所观测到的准周期振动。     

标准薄盘与径移主导吸积流的连接

用标准的龙格-库塔法求解描述黑洞吸积流的基本方程组，没有引入任何附加的能量转移机制和外边界条件，结果表明在强粘滞情况下标准薄盘可以向径移主导吸积流转变。     

Power Spectrum Density of Stochastic Oscillating Accretion Disk

In this paper, we employ a stochastic oscillating accretion disk model for the power spectral index and variability of BL Lac object S5 0716+714. In the model, we assume that there is a relativistic oscillation of thin accretion disks and it interacts with an external thermal bath through a friction force and a random force. We simulate the light curve and the power spectrum density (PSD) at (i) over-damped, (ii) critically damped and (iii) under-damped cases, respectively. Our results show that the simulated PSD curves depend on the intrinsic property of the accretion disk, and it could be produced in a wide interval ranging from 0.94 to 2.05 by changing the friction coefficient in a stochastic oscillating accretion disk model. We argue that accretion disk stochastic oscillating could be a possible interpretation for observed PSD variability.     

The Sub-Pc Scale Accretion Disk of Ngc 4258

Water megamasers have been found to trace parsec/sub-parsec, circumnuclear accretion disks in several AGN (e.g., Circinus, NGC 1068 & NGC 4258). High-spatial (0.5 mas) and velocity resolution (0.2 km s^–1) VLBA imaging of the disks reveals thin, warped pannekoeken (pancake)-style structures as opposed to thick tori in the inner regions of the central engines (40 000 R_sch). In this contribution, I will describe some current investigations into the dynamical and physical attributes of the water maser disk in NGC 4258, as revealed by VLBA, VLA and Effelsberg monitoring over 8 years.     

Simulations of Gas Flow from a Galactic Disk Towards the Black-Hole Accretion Disk

We report preliminary results of hydrodynamical modeling of gas flow in a galaxy potential towards a central massive black hole. We use a bar-like perturbation on the large scale in order to cause the initial inflow, and we concentrate our attention on the inner parts of the galaxy, where the potential becomes axisymmetric, or where it is dominated by an inner, secondary bar. Our high-resolution grid-based algorithm allows us to get a detailed picture of gas dynamics down to about 10 pc from the galaxy center, where the black hole becomes dominant. We find that inner bars may not increase the gas inflow, but for certain potential and gas parameters, gas flows to the center in a spiral shock. This revised version was published online in September 2006 with corrections to the Cover Date.