Electron impact excitation rate coefficients of N II ion

This paper calculates the electron impact excitation rate coefficients from the ground term 2s²2p^{2 3}P to the excited terms of the 2s²2p², 2s2p³, 2s²2p3s, 2s²2p3p, and 2s²2p3d configurations of N II. In the calculations, multiconfiguration Dirac--Fork wave functions have been applied to describe the target-ion states and relativistic distorted-wave calculation has been performed to generate fine-structure collision strengths. The collision strengths are then averaged over a Maxwellian distribution of electron velocities in order to generate the effective collision strengths. The calculated rate coefficients are compared with available experimental and theoretical data, and some good agreements are found for the outer shell electron excitations. But for the inner shell electron excitations there are still some differences between the present calculations and available experiments.     

关于DSX体系下的广义相对论（1PN）流体力学问题的探讨

使用ＤＳＸ 体系对于广义相对论（１ＰＮ） 的一般流体和理想流体均作了初步的探讨,建立了一种既适用于局部坐标系又适用于整体坐标系的解决广义相对论流体力学的新方法．对于一般流体,利用Ｍａｐｌｅ 软件计算了精确到ｃ－ ４ 项的能量动量张量Ｔａｂ 的结构,经过化简整理代到描述流体运动的基本方程中,得到了ＤＳＸ 体系下一般流体的基本方程,这是在局部坐标系中的结果,通过局部坐标和整体坐标之间的变换关系,可得整体坐标下物体的运动状态．另外,还给出了ＤＳＸ 体系下的理想流体力学的表示形式,通过将理想流体力学中一般的量改写为该体系下的量,从而改写了理想流体的Ｅｕｌｅｒ 方程和能量方程     

Differential rotation in compact objects with hyperons and delta isobars

Neutron stars may experience differential rotation on short, dynamical timescales following extreme astrophysical events like binary neutron star mergers. In this work, the masses and radii of differentially rotating neutron star models are computed. We employ a set of equations of states for dense hypernuclear and $\mathrm{\Delta }$-admixed-hypernuclear matter obtained within the framework of CDF theory in the relativistic Hartree-Fock (RHF) approximation. Results are shown for varying meson- $\mathrm{\Delta }$ couplings, or equivalently the $\mathrm{\Delta }$-potential in nuclear matter. A comparison of our results with those obtained for nonrotating stars shows that the maximum mass difference between differentially rotating and static stars is independent of the underlying particle composition of the star. We further find that the decrease in the radii and increase in the maximum masses of stellar models when $\mathrm{\Delta }$-isobars are added to hyperonuclear matter (as initially observed for static and uniformly rotating stars) persist also in the case of differentially rotating neutron stars.     

论相对论重力位及相对论大地水准面

讨论了相对论意义下的重力位及大地水准面,指出了等时率大地水准面的缺陷,建议今后采用等频面及等频大地水准面的概念,给出了等频大地水准面与经典大地水准面的差异,同时给出了等频大地水准面的近似表达式。     

Relativistic magnetofluid disc with nonzero radial velocity in Schwarzschild geometry

In this paper we consider the equilibrium of a magnetofluid disc in Schwarzschild background with an external magnetic field, having the azimuthal and the radial components of the flow velocity nonzero. The electrical conductivityσ of the fluid is taken to be finite and thus the solution for the electromagnetic field is required to satisfy the Ohm’s law too with the four-current having onlyJ ^ϕ andJ ^t nonzero. The various physical parameters that have to correlate for possible equilibrium configurations are identified and their respective magnitudes estimated. It is found that for a given angular momentum distribution the inner edge of the disc can reach well within the usual6m limit only when the surface magnetic field of the central object is not too high when the matter density at the outer edge of the disc and the accretion rate are taken with reasonable limits     

A statistical analysis of gamma-ray bursts based on the beaming model

We assume that gamma-ray bursts come from relativistic beaming in random directions, with the bursts being standard candles in their own rest frames and following a power-law distribution, and that the rate of occurrence is a constant in the comoving frame of the Ω = 1, Λ = 0 Friedmann universe. This model is very sensitive to the beaming velocity. For a Lorentz factor Γ < 10 and a power-law index n < 1.0 our calculated statistics agree with the BATSE data of weak bursts and the PVO data of strong bursts.     

中等质量黑洞活动星系核的射电连续谱研究:总结与展望

中等质量黑洞活动星系核(intermediate mass black hole active galactic nuclei, IMBH AGN)是指中心黑洞大约在10²M⊙¹0⁶M⊙质量范围的活动星系核。关于近邻宇宙中IMBH AGN的研究,对于理解高红移类星体中的超大质量黑洞起源(即"种子黑洞问题")、低频引力波源等基本问题有着重要意义。得益于近20年来大规模光学光谱巡天的发展,已发现近邻宇宙中的宽线IMBH AGN的数目超过500个。对于这些光学选IMBH AGN,基于VLA FIRST巡天数据,针对小样本或个源的专门射电连续谱观测,已取得不少结果。从射电形态、连续谱谱型、射电功率和射电噪度、黑洞吸积基本面这四个方面,详细地介绍了目前IMBH AGN射电连续谱研究的进展。并且,分别面向当前正在开展的几个SKA探路者大规模连续谱巡天项目,以及大约10年后运行的SKA (至少是SKA一期),展望了IMBH AGN领域将来可以进行研究的科学目标。     

类星体3C 273的射电流量和偏振度关系

利用UMRAO数据平台,研究了类星体3C273的射电流量密度与偏振度的关系（包括4.8GHz,8GHz和14.5GHz3个频段）,结果发现偏振度与射电流量在3个频段都具有很强的负相关性。这些结果可能表明3C273的射电流量密度和偏振度的变化与聚束效应无关。一般,偏振度与流量密度的强负相关现象可以用喷流成分＋激波成分的双成分模型来解释：在喷流成分与激波成分的偏振角相互垂直并且偏振度基本相同的情况下,激波在喷流中的传播产生了这些偏振度与流量密度的强负相关性。     

An alternative approach to cosmogony and cosmology

Some problems associated with the big bang cosmological model are briefly discussed. It is shown that the quasi-steady state model (QSSC) is a viable alternative. Moreover, the cosmogony related to this theory is supported by the observations.