Laser Interferometer Space Antenna double black holes: dynamics in gaseous nuclear discs     

Massimo Dotti  Monica Colpi  Francesco Haardt 《Monthly notices of the Royal Astronomical Society》2006,367(1):103-112

We study the inspiral of double black holes, with masses in the Laser Interferometer Space Antenna ( LISA ) window of detectability, orbiting inside a massive circumnuclear, rotationally supported gaseous disc. Using high-resolution smoothed particle hydrodynamics simulations, we follow the black hole dynamics in the early phase when gas-dynamical friction acts on the black holes individually, and continue our simulation until they form a close binary. We find that in the early sinking the black holes lose memory of their initial orbital eccentricity if they corotate with the gaseous disc. As a consequence, the massive black holes bind forming a binary with a low eccentricity, consistent with zero within our numerical resolution limit. The cause of circularization resides in the rotation present in the gaseous background where dynamical friction operates. Circularization may hinder gravitational waves from taking over and leading the binary to coalescence. In the case of counter-rotating orbits, the initial eccentricity (if present) does not decrease, and the black holes may bind forming an eccentric binary. When dynamical friction has subsided, for equal mass black holes and regardless their initial eccentricity, angular momentum loss, driven by the gravitational torque exerted on the binary by surrounding gas, is nevertheless observable down to the smallest scale probed (≃1 pc). In the case of unequal masses, dynamical friction remains efficient down to our resolution limit, and there is no sign of formation of any ellipsoidal gas distribution that may further harden the binary. During inspiral, gravitational capture of gas by the black holes occurs mainly along circular orbits; eccentric orbits imply high relative velocities and weak gravitational focusing. Thus, the active galactic nucleus activity may be excited during the black hole pairing process and double active nuclei may form when circularization is completed, on distance scales of tens of parsecs.  相似文献   

Probing the nuclear activity with supermassive black holes     

V.D. Ivanov  A. Alonso-Herrero 《Astrophysics and Space Science》2003,284(2):565-568

We report three new or updated techniques for probing the parameters of active galaxies based on the masses of their central black holes M_BH). First, we derived a near-IR analog of the bulge luminosity versus M_BH relationship. The low scatter makes it a promising new tool to study the black hole demographics. Next, we present relations between M_BH and the10 μm and 2-10 keV nuclear luminosity. They may help to study the M_BH evolution over wide redshift ranges. Finally, we measured M_BH in quasars from z ∼ 3.4 to z ∼ 0.3 to search directly for M_BH growth. Surprisingly, we found no evidence for growth implying that the majority of quasar host galaxies have undergone their last major merger at z ≥ 3. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

The efficiency of the spiral-in of a black hole to the Galactic Centre     

Piero F. Spinnato  Michael Fellhauer  Simon F. Portegies Zwart 《Monthly notices of the Royal Astronomical Society》2003,344(1):22-32

We study the efficiency at which a black hole or dense star cluster spirals in to the Galactic Centre. This process takes place on a dynamical friction time-scale, which depends on the value of the Coulomb logarithm (ln Λ). We determine the accurate value of this parameter using the direct N -body method, a tree algorithm and a particle-mesh technique with up to two million plus one particles. The three different techniques are in excellent agreement. Our measurement for the Coulomb logarithm appears to be independent of the number of particles. We conclude that  ln Λ= 6.6 ± 0.6  for a massive point particle in the inner few parsec of the Galactic bulge. For an extended object, such as a dense star cluster, ln Λ is smaller, with a value of the logarithm argument Λ inversely proportional to the object size.  相似文献   

A simple model for lensing by black holes in galactic nuclei     

M. C. Werner  N. W. Evans 《Monthly notices of the Royal Astronomical Society》2006,368(3):1362-1368

The lensing properties of the Plummer model with a central point mass and external shear are derived, including the image multiplicities, critical curves and caustics. This provides a simple model for a flattened galaxy with a central supermassive black hole. For the Plummer model with black hole, the maximum number of images is four, provided the black hole mass is less than an upper bound which is calculated analytically. This introduces a method to constrain black hole masses by counting images, thus applicable at cosmological distance. With shear, the maximum number of images is six and we illustrate the occurrence of an astroid caustic and two metamorphoses.  相似文献   

地下洞库勘察中的深斜孔钻探和压水试验技术          下载免费PDF全文

吉孟瑞  孙桂明  吴昌庆  原华山 《山东国土资源》2001,17(2):56-60

青岛市黄岛区拟建设海底地下油气储藏库,前期地质勘察工作要求施工倾角45°、深220m的取心钻孔4个,并在孔内分段进行压水试验.本文介绍了如何利用XY-4型金刚石小口径钻机施工基岩深斜孔及压水试验技术.  相似文献   

The Geological-Geophysical-Geochemical Exploration Model of the Nancha Type Gold Deposit in Tonghua Area, Jilin Province     

《东北亚地学研究》2001,(2)

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无规取向、无吸收非球形粒子光散射的T-矩阵方法     

丁继烈  许丽生 《成都信息工程学院学报》2001,16(3):159-168

较详细地研究了无规取向、无吸收椭球体粒子的T－矩阵收敛问题。首先，简要概括了nmax的3种收敛方案和它们的基本特性。然后，应用1993年提出的数学收敛方法（M－方法）和1998年提出和物理收敛方法（P－方法）研究收敛问题。结果表明椭球粒子收敛精度对粒子的尺度参数，纵横比以及椭球体的种类（例如，长／扁椭球）有很强的依赖性。当粒子的尺度参数不太大时，甚至在极端纵横比的条件下，P－收敛方案优于M－收敛方案。  相似文献   

瞬变电磁法在断层含水性评价中的应用          下载免费PDF全文

郁万彩 《山东国土资源》2001,17(1):52-55

本文介绍了瞬变电磁法在煤矿水文地质勘探中的具体应用效果.采用瞬变电磁法对落差较大断层的含(导)水性进行测量,不仅可有效地控制断层的空间位置,而且可定性地判断断层的富水性,其测量结果与已知水文地质资料吻合较好.  相似文献   

山东省黄金资源可持续开发利用     

徐金芳 《山东国土资源》2001,(Z1)

本文扼要介绍了山东省金矿地质勘查、开发现状及存在的环境问题 ,为确保山东省黄金资源可持续开发利用 ,提出要保证黄金资源的可持续供给 ,要在资源开发过程中保护好环境 ,以及要高度重视地勘单位和矿山企业自身的可持续发展等建议。  相似文献   

The range of effects of azimuthal isotropy and EDA anisotropy in sedimentary basins   总被引：4，自引：0，他引：4  

Philip Wild  Stuart Crampin 《Geophysical Journal International》1991,107(3):513-529

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