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The radio structure of BL Lac object S5 2007+777

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 187-190页

作者： WU ZhongZu1,3,GU MinFeng2 & CHEN YongJun2 1 College of Science,Guizhou University,Guiyang 550025,china 2 key laboratory for research in galaxies and cosmology,shanghai astronomical observatory,chinese academy of sciences,shanghai 200030,china 3 NAOC-GZU Sponsored Center for Astronomy,Guizhou University,Guiyang 550025,china Guizhou Univ Coll Sci Guiyang 550025 Peoples R China chinese Acad Sci Shanghai Astron Observ Key Lab Res Galaxies & Cosmol Shanghai 200030 Peoples R China Guizhou Univ NAOC GZU Sponsored Ctr Astron Guiyang 550025 Peoples R China

BL Lac object S5 2007+777 has been classified as a HYMOR(Hybrid Morphology radio source) for its hybrid FR I and FR II radio *** is one of four BL Lac objects with a kpc scale extended X-ray *** this paper,we searched the unpublished European VLBI Network(EVN) archived high resolution data for this source,and present the high resolution radio *** EVN images all show a core-jet structure in 1.6,5 and 8 *** combination with the VLA data in the literature,we found position angle differences(△PA) of about 10°-20° between pc and kpc scale jet *** brightness temperature estimated from multi-band EVN images are around 1011.2-1011.8 K,from which the Doppler factor ranges from 3.2 to *** found significant flux variations of the radio core in 1.6 and 5 GHz,from which we derived the variability in brightness temperature Tvar to be 1013.6 K and 1014.0 K,corresponding to the Doppler factors of 9.3 and 12.4,respectively.

关键词： active galactic nuclei VLBI BL Lac objects

Some developments of hot accretion flow theory in the past ten years

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 24-30页

作者： YUAN Feng key laboratory for research in galaxies and cosmology,shanghai astronomical observatory,chinese academy of sciences,shanghai 200030,china 1. key laboratory for research in galaxies and cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China

The hot accretion flow model was re-discovered in 1994 by Narayan and *** theoretical works have been conducted and significant progresses have been *** this paper,we review several developments in the past ten *** mainly includes the finding of outflow and convection and its dynamical effect on inflow;the direct electron heating by viscous dissipation;the effect of large scale toroidal magnetic fields in the inner region of the accretion flow;and the effect of global Compton *** observational applications are also introduced very briefly.

关键词： flow Some developments of hot accretion flow theory in the past ten years

Numerical simulation of hot accretion flows with thermal conduction

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 168-172页

作者： WU MaoChun,YUAN Feng & BU DeFu key laboratory for research in galaxies and cosmology,shanghai astronomical observatory,chinese academy of sciences,shanghai 200030,china 1. key laboratory for research in galaxies and cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China

We report on the effects of isotropic thermal conduction in non-radiative collisionless accretion flows in two *** comparison to accretion flows without conduction,we find that the disk generally becomes cooler and ***,the magnitude of this effect depends on the kinetic viscosity *** it is proportional to density,the density profile of the accretion flow is flat,therefore the effect is not very ***,if it is proportional to r1/2,as is usual for the "α" disk description,the density profile is ***,the effect will be much more obvious,with the temperature profile of the accretion flow becoming much *** will have important observational consequences.

关键词： black hole accretion disk thermal conduction

On the effect of injection of gas in the numerical simulation of accretion flows

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 139-142页

作者： BU DeFu,YUAN Feng,WU MaoChun & YANG XiaoHong key laboratory for research in galaxies and cosmology,shanghai astronomical observatory,chinese academy of sciences,shanghai 200030,china 1. key laboratory for research in galaxies and cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China

We investigate the effects of various ways of injection of gas at the outer boundary in the numerical simulations of non-viscous accretion *** study three *** Model A,we inject material around the equatorial *** Models B and C,fullrange θ injection is used(we employ spherical coordinates).In all three models,the injected material has the same density distribution with polar angle θ.From the equatorial region to the polar regions,angular momentum of the injected material of Model B decreases faster than that in Model *** all of the models,after a transient episode of infall at the beginning of the simulations,the gas piles up in the equatorial regions outside the black hole and forms a thick torus bounded by a centrifugal *** find that the accretion rates of Models B and C are more than ten times higher than that in Model *** Model A,there is weak accretion only in the torus and outflows are found on the surface of the *** Model B,we find strong inflows on the surface of its torus,and the accretion in the torus is *** Model C,strong inflows also occur on the surface of its torus,but the accretion regions are narrower and there are strong outflows in its *** all of our models,the time-averaged density,pressure and angular momentum in the equatorial region can be described by a radial power law,with P ∝r-3/2,P ∝r-2 and l∝r0.

关键词： accretion accretion discs-black hole physics-hydrodynamics numerical

The relation between black hole masses and Lorentz factors of the jet components in blazars

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research in Astronomy and Astrophysics 2009年第3期9卷 293-301页

作者： Ming Zhou1,2,3 and Xin-Wu Cao1,2 1 shanghai astronomical observatory, chinese academy of sciences, shanghai 200030, china 2 Joint Institute for Galaxy and cosmology (JOINGC) of SHAO and USMC, shanghai 200030, china 3 Graduate School of the chinese academy of sciences, Beijing 100049, china shanghai astronomical observatory Chinese Academy of Sciences Shanghai 200030 China Joint Institute for Galaxy and cosmology (JOINGC) of SHAO and USMC Shanghai 200030 China Graduate School of the chinese academy of sciences Beijing 100049 China

We explore the relationship between black hole mass (MBH) and the motion of the jet components for a sample of blazars. The Very Long Baseline Array (VLBA) 2 cm Survey and its continuation: Monitoring of Jets in active galactic nuclei (AGNs) with VLBA Experiments (MOJAVE) have observed 278 radio-loud AGNs, of which 146 blazars have reliable measurements of their apparent velocities of the jet components. We calculate the minimal Lorentz factors for these sources from their measured apparent velocities, and their black hole masses are estimated with their broad-line widths. A sig- nificant intrinsic correlation is found between black hole masses and the minimal Lorentz factors of the jet components. The Eddington ratio is only weakly correlated with the min- imal Lorentz factor, which may imply that the Blandford-Znajek (BZ) mechanism may dominate over the Blandford-Payne (BP) mechanism for the jet acceleration (at least) in blazars.

关键词： black hole physics — galaxies: active — galaxies: jets — galaxies: nuclei

Multi-epoch X-ray observations of the narrow-line Seyfert 1 galaxy SDSS J160508.87+323921.4 with XMM-Newton

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 207-211页

作者： AI YanLi1,2,3,YUAN WeiMin1,2,ZHOU HongYan4,5 & WANG JianGuo1,2,3 1 National astronomical Observatories/Yunnan observatory,chinese academy of sciences,Kunming 650011,china 2 key laboratory for the Structure and Evolution of Celestial Objects,chinese academy of sciences,Kunming 650011,china 3 Graduate University of the chinese academy of sciences,Beijing 100049,china 4 Center for Astrophysics,University of Science and Technology of china,Hefei 230026,china 5 Joint Institute of galaxies and cosmology,SHAO and USTC,shanghai 200030,china 1. National astronomical Observatories/Yunnan observatory Chinese Academy of Sciences Kunming 650011 China 2. key laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China 3. Graduate University of the chinese academy of sciences Beijing 100049 China 4. Center for Astrophysics University of Science and Technology of China Hefei 230026 China 5. Joint Institute of galaxies and cosmology SHAO and USTC Shanghai 200030 China

We present results of multi-epoch XMM-Newton observations separated by several years of the narrow-line Seyfert 1(NLS1) galaxy,SDSS J160508.87+*** NLS1 showed X-ray flux variations on timescales of years as well as low amplitude variations on timescales as short as hours,while the X-ray spectral shape remained essentially *** spectrum shows a significant soft X-ray *** model of reflection from an ionized disc,that is dominant in the whole XMM-Newton bandpass,provides the best description of the observed spectra for all the observations,though alternatives such as Compton scattering(T-0.25 keV) cannot be ruled out in a statistical *** the disc reflection model,the observed variations may originate either from the change in the reflection fraction,or from the variability of the intrinsic X-ray luminosity.

关键词： galaxies:active Seyfert X-rays individual

Birthrates and delay times of Type Ia supernovae

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Science china(Physics,Mechanics & Astronomy) 2010年第3期53卷 586-590页

作者： WANG Bo1,2,3, LIU ZhengWei1,2,3, HAN YunKun1,2,3, LEI ZhenXin1,2,3, LUO YangPing1,2,3 & HAN ZhanWen1,2 1National astronomical Observatories/Yunnan observatory, chinese academy of sciences, Kunming 650011, china 2key laboratory for the Structure and Evolution of Celestial Objects, chinese academy of sciences, Kunming 650011, china 3Graduate University of chinese academy of sciences, Beijing 100049, china 1. National astronomical Observatories/Yunnan observatory Chinese Academy of Sciences Kunming 650011 China2. Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China3. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Type Ia supernovae (SNe Ia) play an important role in diverse areas of astrophysics, from the chemical evolution of galaxies to observational cosmology. However, the nature of the progenitors of SNe Ia is still unclear. In this paper, according to a detailed binary population synthesis study, we obtained SN Ia birthrates and delay times from different progenitor models, and compared them with observations. We find that the Galactic SN Ia birthrate from the double-degenerate (DD) model is close to those inferred from observations, while the birthrate from the single-degenerate (SD) model accounts for only about 1/2-2/3 of the observations. If a single starburst is assumed, the distribution of the delay times of SNe Ia from the SD model is a weak bimodality, where the WD + He channel contributes to the SNe Ia with delay times shorter than 100 Myr, and the WD + MS and WD + RG channels to those with age longer than 1 Gyr.

关键词： binaries: close stars: evolution supernovae: general white dwarfs

Long-term variation time scales in OJ 287

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research in Astronomy and Astrophysics 2010年第11期10卷 1100-1108页

作者： Jun-Hui Fan Yi Liu Bo-Chun Qian Jun Tao Zhi-Qiang Shen Jiang-Shui Zhang Yong Huang Jin Wang Center for Astrophysics Guangzhou University Guangzhou 510400 China Astronomy Science and Technology research laboratory. of Department of Education of Guangdong Province Guangzhou 510006 China shanghai astronomical observatory Chinese Academy of Sciences Shanghai 200030 China Joint Institute for Galaxy and cosmology ShAO and USTC Chinese Academy of Sciences China

The light curve data from 1894 to 2008 are compiled for the BL Lacertae object OJ 287 from the available literature. Periodicity analysis methods （the Discrete Correlation Function-DCF, the Jurkevich method, the power spectral （Fourier） analysis, and the CLEANest method） are performed to search for possible periodicites in the light curve of OJ 287. Significance levels are given for the possible periods. The analysis results confirm the existence of the 12.2 ± 0.6 yr time scale and show a hint of a -53 yr time scale. The 12.2 ± 0.6 yr period is used as the orbital period to investigate the supermassive binary black hole system parameters.

关键词： galaxies active -- galaxies: general-- methods: data analysis -- galax- ies individual (OJ 287)

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宇宙大尺度结构数值模拟的研究进展

天文学进展 2018年第2期36卷 136-172页

作者：唐林林伟鹏中国科学院上海天文台星系与宇宙学重点实验室上海200030 中国科学院大学北京100049 中山大学物理与天文学院广州510275

宇宙的结构是由初始密度扰动发展而成的。在引力和宇宙膨胀的作用下,初始密度扰动不断增长,经过线性和非线性阶段,逐渐演化为现今的宇宙结构。在一个给定的宇宙学模型下,可以用一系列动力学方程来描述宇宙中暗物质和重子物质的运动及演... 详细信息

宇宙的结构是由初始密度扰动发展而成的。在引力和宇宙膨胀的作用下,初始密度扰动不断增长,经过线性和非线性阶段,逐渐演化为现今的宇宙结构。在一个给定的宇宙学模型下,可以用一系列动力学方程来描述宇宙中暗物质和重子物质的运动及演化历史。在过去的几十年间,随着算法的完善和计算机技术的发展,从最初几十个粒子的纯引力模拟到1010个粒子在秒差距量级的多体加流体动力学模拟,大量不同的数值模拟技术被用来研究宇宙结构的形成和演化。在这个过程中,数值模拟的分辨率和精度不断提高,模型中对重子物质物理过程的描述也越来越完善。这些模拟技术与观测结果相结合,使人们对宇宙的大尺度结构以及星系团的形成和演化有了更深刻的理解,也在一定程度上影响了观测的发展方向和设备研发。不同数值模拟结果在纯引力研究方面得到了较好的统一,但不同的星系模型使得流体模拟的结果存在较大的差异。

关键词：宇宙大尺度结构星系形成和演化数值模拟多体动力学流体动力学