Correlations of Active Galactic Nuclei with Microquasars

Correlations of active galactic nuclei （AGNs） with microquasars are discussed based on the coexistence of the Blandford-Znajek （BZ） and magnetic coupling （MC） processes （CEBZMC） in black hole （BH） accretion disk. The proportions of several quantities of BH systems for both AGNs and microquasars are derived by combining the observational data with CEBZMC. It is shown that the square of the magnetic field at the BH horizon is inversely proportional to the BH mass, while the accretion rate of the disk is proportional to the BH mass. In addition, the very steep emissivity indexes from the recent XMM-Newton observations of the nearby bright Seyfert 1 galaxy MCG-6-30-15 and the microquasars XTE J1650-500 are well fitted by considering the MC effects on the disk radiation. These results suggest strongly the correlations of A GNs with microquasars.     

A Multi-parameter Model for Radio Dichotomy of Active Galactic Nuclei and Jets

Based on the coexistence of the Blandford-Znajek and magnetic coupling processes in black hole (BH) accretion disc, a multi-parameter model for jet powers and radio loudness of active galactic nuclei (AGNs) is studied. It turns out that radio-loudness of AGNs could be governed by five parameters: (i) the BH spin, (ii) a power-law index of the variation of the magnetic field on the disc; (iii) a parameter determining the position of the inner edge of the disc, (iv) the ratio of the pressure of the magnetic field on the horizon to the ram pressure of the innermost parts of an accretion flow, and (v) the ratio of the angular velocity of the open field lines to that of the horizon. The observed dichotomy between radio-loud and radio-quiet AGNs is well interpreted by the effects of the above parameters. Furthermore, we discuss the derivative of radio loudness of AGNs with respect to each parameter separately. In addition, the effect of the screw instability on radio loudness of AGNs is discussed.     

Two Mechanisms for Extracting Energy and Angular Momentum from a Rotating Black Hole

Two mechanisms of extracting energy and angular momentum from a rotating black hole, the Blandford-Znajek (BZ) process and magnetic coupling (MC) of a rotating black hole (BH) with the surrounding accretion disk, are discussed in detail by using a modified equivalent circuit. We obtain the same value for the BZ power as given by Lee. The strength of the power and torque produced by the rotating BH in the BZ process are compared with those in MC process. In addition, entropy production on the BH horizon due to the BZ process and that due to MC process are compared and discussed also by using the modified equivalent circuit.     

Temperature Profile of Black Hole Accretion Disc with Magnetic Coupling

Two new mapping relations between the angular coordinate on the black hole (BH) horizon and radialcoordinate on the disc are given according to the requirement of general relativity and Maxwell‘s equations, and theeffects of magnetic coupling (MC) on temperature of accretion disc are investigated by comparing with pure accretion.It is shown that the MC effects on the temperature profile are related intimately to the BH spin, and the influenceon the peak value of disc temperature based on the modified mapping relations is not as great as that based on thelinear mapping.The peak value and the corresponding radius of peak value ring of disc temperature do not increasemonotonically as the increasing spin of BH, each containing a maximum for the fast-spinning BH. The value ranges ofthe bolometric luminosity and color temperature of the disc are both extended by the MC effects.     

Black hole binaries and microquasars

This is a general review Oil the observations and physics of black hole X-ray binaries and microquasars, with the emphasize on recent developments in the high energy regime. The focus is put on understanding the accretion flows and measuring the parameters of black holes in them. It includes mainly two parts： i） Brief review of several recent review article on this subject; ii） Further development on several topics, including black hole spin measurements, hot accretion flows, corona formation, state transitions and thermal stability of standard think disk. This is thus not a regular bottom-up approach, which I feel not necessary at this stage. Major effort is made in making and incorporating from many sources useful plots and illustrations, in order to make this article more comprehensible to non-expert readers. In the end I attempt to make a unification scheme on the accretion-outflow （wind/jet） connections of all types of aecreting BHs of all accretion rates and all BH mass scales, and finally provide a brief outlook.     

磁场对黑洞吸积盘的能量提取及其天体物理应用

考虑到螺旋不稳定性的影响, 提出了一种黑洞磁层的新磁场位形(NCMF). 其中涉及到磁场提取能量的三种机制: (1) Blandford-Znajek (BZ)过程; (2)磁耦合(MC)过程; (3) 通过开磁力线联系吸积盘和天体物理负载,并提取吸积盘的旋转能量新机制(文中称为DL过程). 利用两类等效电路导出上述三种提能机制的功率和力矩的表达式. 结果表明,在新磁场位形中提能功率和效率比未考虑螺旋不稳定性的磁场位形有所增大,新磁场位形导出的非常陡的发射率指数可以拟合XMM-Newton天文卫星对邻近的明亮的Seyfert 1星系MCG-6-30-15的观测结果.     

The Pulsational Instability of Non-Isothermal Magnetized Accretion Disk with Self-Gravity in the Transition Zone

By analyzing the fifth-order dispersion relation, the influence of coupled magnetic field and self-gravity on the pulsational instability of gas pressure dominated accretion disk is investigated. Our main results are that the viscous modes become more stable with the increase of self-gravity, magnetized field and viscosity, while they enhance the instabilities of acoustic modes. The effect of self-gravity to the instability is much greater than that of magnetic field in transition zone of the accretion disk. Especially, the self-gravity affects the thermal-modes and acoustic modes strongly. Finally, we discuss our results.     

黑洞阴影在SSD中的位置和形状

假设旋转的黑洞在标准吸积盘内,在吸积盘的内边界等于最后稳定轨道的情况下,画出黑洞阴影在吸积盘的图像.通过定性和定量分析黑洞的形状和位置,发现对于相同质量的黑洞,黑洞阴影的大小及形状与黑洞的自旋参量有关.旋转黑洞阴影的形状和位置与它的旋转轴是不对称的,通过研究旋转轴与黑洞阴影的位置关系来确定黑洞的质量中心的位置及黑洞的旋转参量.     

Evolution Characters of Thermodynamic Quantities in Thin Disk-Accretion of Black Holes

Evolution characters of thermodynamic quantities of the central black hole (BH) of an accretion disk. such as temperature, entropy and specific heat, are investigated in prograde accretion and retrograde accretion, respectively. Compared with prograde accretion, a BH has some unusual characters in retrograde accretion: (i) There exists a maximum BH temperature; (ii) There exists an infinite discontinuity of BH specific heat; (iii) The rates of change of BH temperature and entropy are much bigger for fast-spinning BH than those for slowly-spinning BH.     

Observable signatures of a black hole ejected by gravitational-radiation recoil in a galaxy merger

According to recent simulations, the coalescence of two spinning black holes (BHs) could lead to a BH remnant with recoil speeds of up to thousands of km s(-1). Here we examine the circumstances resulting from a gas-rich galaxy merger under which the ejected BH would carry an accretion disk and be observable. As the initial BH binary emits gravitational radiation and its orbit tightens, a hole is opened in the disk which delays the consumption of gas prior to the eventual BH ejection. The punctured disk remains bound to the ejected BH within the region where the gas orbital velocity is larger than the ejection speed. For a approximately 10(7) M[middle dot in circle] BH the ejected disk has a characteristic size of tens of thousands of Schwarzschild radii and an accretion lifetime of approximately 10(7) yr. During that time, the ejected BH could traverse a considerable distance and appear as an off-center quasar with a feedback trail along the path it left behind.     

The Radial-Azimut ha1 Inst ability of an Isothermal Magnetized Accretion Disk

The radial-azimuthal instability of an isothermal magnetized accretion disk is examined in this paper. We find that the azimuthal perturbation enhances the instability of the magneto-acoustic and non-axisymmetric modes. The magnetic field induces and enhances the instability of magneto-acoustic modes, but stabilizes the non-axisymmetric modes in the outer disk. The viscous modes are always stable. The instability of magneto-acoustic modes are dominant in this disk.     

Constraints on Mass,Spin and Magnetic Field of Microquasar H 1743-322 from Observations of QPOs

The study of quasi-periodic oscillations (QPOs) of X-ray flux observed in many microquasars can provide a powerful tool for testing of the phenomena occurring in strong gravity regime. QPOs phenomena can be well related to the oscillations of charged particles in accretion disks orbiting Kerr black holes immersed in external large-scalemagnetic fields. In the present paper we study the model ofmagnetic relativistic precession and provide estimations of the mass and spin of the central object of the microquasar H 1743-322 which is a candidate for a black hole. Moreover, we discuss the possible values of external magnetic field and study its influence on the motion of charged particles around rotating black hole.     

X-ray signatures of cold accretion disks in AGNs

Summary We have calculated, by means of Monte Carlo simulations, the properties of the radiation emerging from an X-ray illuminated cold accretion disk. These calculations can apply to AGNs, for which there is evidence of cold, optically thick matter near the central black hole. The resulting spectra show an intense iron fluorescent line and a high-energy bump above about 10 keV, where the scattering becomes important with respect to the photoabsorption; these features have been observed by GINGA in some bright Seyfert 1 galaxies. Our detailed results are indicative of the type of future observations which would lead to estimates of the geometrical parameters of the disk, its iron abundance and the mass of the black hole. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

Extracting Energy Magnetically from Plunging Region of Black-Hole Accretion Disk

An analytical expression for the jet power extracted from the plunging region between a black hole (BH)horizon and the inner edge of the disk (hereafter the PL power) is derived based on an improved equivalent circuit in BH magnetosphere with a mapping relation between the radial coordinate of the plunging region and that of the remote astrophysical load.It is shown that the PL power is of great importance in explaining jet power and dominates over the BZ and DL powers for a wide value range of the BH spin.In addition,we show that the PL power derived in our model can be fitted with the strong jet powers of several 3CR FR I radio galaxies,which cannot be explained by virtue of the BZ mechanism.Furthermore,the condition for negative energy of the accreting particles in the plunging region is discussed with the validity of the second law of BH thermodynamics.     

Circular geodesics and accretion disk in the spacetime of a black hole including global monopole

We study circular time-like geodesics in the spacetime of a black hole including global monopole. We show that when the range of parameter changed the properties of the circular geodesics and the radiation of accretion disks are different. It follows that the properties of the accretion disk around black hole including global monopole can be different from that of a disk around Schwarzschild black hole.     

振荡吸积盘的光变研究

理论研究指出随机振荡吸积盘可能引起活动天体的光变,然而观测数据分析表明光变中除了含有随机噪声外还存在混沌因素.将混沌因素引入到随机振荡吸积盘中,构成"混沌+随机"振荡吸积盘模型.通过分析扰动的相图,直观再现了混沌吸引子的状态.研究结果表明:在随机因素占主导时,光变混乱无序;随机因素与混沌因素相当时,光变上下起伏类似于心电图;混沌因素占主导时,光变具有一定有序性.模拟光变曲线的关联维与观测数据的关联维一致,表明模拟光变曲线与观测结果之间存在内在联系.     

On the mean radiative efficiency of accreting massive black holes in AGNs and QSOs

Radiative efficiency is an important physical parameter that describes the fraction of accretion material converted to radiative energy for accretion onto massive black holes (MBHs). With the simplest So?tan argument, the radiative efficiency of MBHs can be estimated by matching the mass density of MBHs in the local universe to the accreted mass density by MBHs during AGN/QSO phases. In this paper, we estimate the local MBH mass density through a combination of various determinations of the correlations between the masses of MBHs and the properties of MBH host galaxies, with the distribution functions of those galaxy properties. We also estimate the total energy density radiated by AGNs and QSOs by using various AGN/QSO X-ray luminosity functions in the literature. We then obtain several hundred estimates of the mean radiative efficiency of AGNs/QSOs. Under the assumption that those estimates are independent of each other and free of systematic effects, we apply the median statistics as described by Gott et al. and find the mean radiative efficiency of AGNs/QSOs is ∈= 0.105_(0.008)~(+0.006), which is consistent with the canonical value ~0.1. Considering that about 20% Compton-thick objects may be missed from current available X-ray surveys,the true mean radiative efficiency may be actually ~0.12.     

Substructures in Simulations of Relativistic Jet Formation

We present a set of simulations of relativistic jets from accretion disk initial setup with numerical solutions of a system of general-relativistic magnetohydrodynamics (GRMHD) partial differential equations in a fixed black hole (BH) spacetime which is able to show substructures formations inside the jet as well as lobe formation on the jet head. For this, we used a central scheme of finite volume method without dimensional split and with no Riemann solvers namely the Nessyahu-Tadmor method. Thus, we were able to obtain stable numerical solutions with spurious oscillations under control and with no excessive numerical dissipation. Therefore, we developed some setups for initial conditions capable of simulating the formation of relativistic jets from the accretion disk falling onto central black hole until its ejection, both immersed in a magnetosphere. In our simulations, we were able to observe some substructure of a jet created from an accretion initial disk, namely, jet head, knots, cocoon, and lobe. Also, we present an explanation for cocoon formation and lobe formation. Each initial scenario was determined by ratio between disk density and magnetosphere density, showing that this relation is very important for the shape of the jet and its substructures.     

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

A radial-azimuthal instability analysis of a radiation-pressure-dominated accretion disk with advection is presented. We find that the including of a very little advection has significant effect on two acoustic modes, which are no longer complex conjugates of each other. With the increase of azimuthal perturbations, the thermal mode becomes more unstable and the viscous mode more stable, but there has no effect on acoustic mode. For geometrically slim and advection-dominated disks, the azimuthal perturbation and increasing of advection do not affect the stability of all the modes.     

X-ray emission from non-Keplerian magnetically dominated accretion disks

Summary Most accretion disk models do assume Keplerian rotation as the ?natural? one. This is not so obvious and is somewhat aprioristic, as shown by some attempts to follow different approaches. In the present work we suggest a new approach to the problem, pointing out that the disk structure is deeply related to the balance between the magnetic energy produced by dynamo action and the rotational energy associated with the accreting flow. This balance, together with the conservation laws, allows us to derive analytically the angular-velocity field, the radial velocity field and the magnetic-energy distribution inside the disk. As far as the disk X-ray emission is concerned, we adopt the point of view that the buoyancy and emergence at the disk surface of the azimuthal magnetic field generated by differential rotation gives rise to looplike structures in a hot magnetically confined corona, which is not merely overimposed, as in other models, but ?naturally? fits to the disk structure. The magnetic-energy dissipation into the coronal medium, which sustains the X-ray luminosity, is due to twisting of the magnetic loops. we give an exact analytical expression for the integrated luminosityL _x in terms of the mass of the compact object, the accretion rate, the disk size and rotational velocity, and show that in the limitr _i≪r _e (wherer _i andr _e are the inner and the outer radius of the accretion disk, respectively) it agrees fairly well with the characteristic observed values of both galactic and extragalactic strong compact sources, within the reasonable range commonly accepted for the relevant parameters. Paper presented at the 2° Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984.