检索结果-南通市图书馆

Magnetic extraction of energy from black hole accretion disc and its application to astrophysics

Chinese Physics B 2005年第2期14卷 439-447页

作者：叶永春汪定雄龚小龙 DepartmentofPhysics HuazhongUniversityofScienceandTechnologyWuhan430074China

A new configuration of magnetic field (NCMF) in black hole (BH) magnetosphere is proposed by considering the effects of the screw instability. Three mechanisms of extracting energy magnetically are involved in the NCMF: (1)the Blandford-Znajek (BZ) process; (2) the magnetic coupling (MC) process; (3) a new scenario (henceforth the DL process) for extracting rotational energy from the disc, which is related to the open field lines connecting the disc with the astrophysical load. The expressions for the powers and torques of the above energy mechanisms are derived by using two kinds of the equivalent circuits. It turns out that the power and efficiency of extracting energy magnetically from the BH accretion disc are all augmented in the NCMF. It is shown that a very steep emissivity can be produced in a NCMF,which is consistent with the recent XMM-Newton observation of the nearby bright Seyfert 1 galaxy MCG-6-30-15.

关键词： black holes black hole physics accretion discs emissivity index

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Modeling the quasi-periodic oscillation of Swift J1644+57

引用

Research in Astronomy and Astrophysics 2020年第2期20卷 31-36页

作者： Meng-Meng Zheng Shuang-Xi Yi Fa-Yin Wang Yuan-Chuan Zou School of Physics and Physical Engineering Qufu Normal UniversityQufu 273165China School of Astronomy and Space Science Nanjing UniversityNanjing 210093China School of Physics Huazhong University of Science and TechnologyWuhan 430074China

A 200-second X-ray quasi-periodicity in the 2-8 ke V band from Swift J1644+57 was found by Reis et *** the onset time of quasi-periodic oscillation(QPO),we show that Swift J1644+57 is a plunging *** QPO may be related to discrete clumps from the accretion disk falling into a supermassive black hole,then the outflow in the jet may be also *** estimate the lifetime of clumps to be about several hundreds seconds and the fraction of clumpy ejecta to be about 30% from the *** other possible model involves the interface between the inflow and jet magnetosphere in the magnetically choked accretion *** and numerical simulations indicate that a magnetic Rayleigh-Taylor and Kelvin-Helmholtz unstable magnetospheric interface can produce a jet-disk QPO *** event may be the first evidence of jet-disk *** observations,the two models are comparable.

关键词： accretion accretion discs gamma-ray burst:general radiation mechanism:non-thermal

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A report on TypeⅡX-ray bursts from SMC X-1

引用

Research in Astronomy and Astrophysics 2018年第12期18卷 43-52页

作者： Binay Rai Pragati Pradhan Bikash Chandra Paul Dept.of Physics North Bengal UniversityDarjeelingWest Bengal734013India Department of Astronomy and Astrophysics Pennsylvania State UniversityPennsylvania16802USA St.Joseph's College Darjeeling-734104West BengalIndia

We study RXTE PCA data for the high mass X-ray binary source SMC X-1 between 2003–10 and 2003–12 when the source was in its high *** source is found to be frequently bursting which can be seen as flares in lightcurves that occur at a rate of one every 800 s, with an average of 4–5 Type Ⅱ X-ray bursts per *** note that typically a burst was short, lasting for a few tens of seconds in addition to a few long bursts spanning more than a hundred seconds that were also *** flares apparently occupied 2.5% of the total observing time of 225.5 *** note a total of 272 flares with mean FWHM of the flare ～21 *** rms variability and aperiodic variability are independent of *** observed, the pulse profiles of the lightcurves do not change their shape, implying that there is no change in the geometry of an accretion disk due to a *** hardness ratio and rms variability of lightcurves exhibit no correlation with the *** flare fraction shows a positive correlation with the peak-to-peak ratio of the primary and secondary peaks of the pulse *** observed hardening or softening of the spectrum cannot be correlated with the flaring rate but may be due to the interstellar absorption of X-rays as evident from the change in hydrogen column density(n_H).It is found that the luminosity of the source increases with the flaring *** that the viscous timescale is equal to the mean recurrence time of flares, we fixed the viscosity parameter α ～ 0.16.

关键词： accretion accretion discs pulsar:individual(SMC X-1) stars:neutron X-rays:binaries X-ray:burst

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The Effects of A Varying accretion Rate and Spiral Density Waves in BHB accretion Disks

The Effects of A Varying Accretion Rate and Spiral Density W...

引用

作者： Gleniese E.McKenzie 中国科学技术大学

学位级别：硕士

Most accretion disc models consider the accretion rate to be steady and nonvarying or run disk simulations with one accretion rate at a time to determine how the different rates affect disk dynamics. However, in the case of a black hole accreting from its companion star, the accretion rate should progressively vary since the star may still be evolving and because of additional mass that is loss via the stellar winds. In order to investigate how a varying accretion rate in the context of spiral density waves effect the dynamics of the disc:I use the recently made public code, Fargo3d, to simulate the effects of a varying accretion rate and compare them with a simulation of a consistent accretion rate. Three different accretion rates, one of which was constant, were supplied to magnetized thin disks with an aspect ratio of0.1. The results indicate that there is indeed a difference between a constant accretion rate and a varying one as both of the disks with the varying accretion rates produced more turbulence over time, i.e. a high value of alpha(the turbulent velocity over the sound speed), than the constant accretion rate. It is also worth noting that the accretion rate with the least total mass of the three had a greater value than the constant accretion rate. This may have great implications in the way we view disk models as the assumption of a constant accretion rate may not be as inconsequential as proposed.

关键词： accretion discs accretion rate X-ray Binaries Numerical Simulation Instabilities

来源：

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：