Melted cast iron was inoculated by FeSi,then quenched to interrupt the dissolution, the non-metallic inclusions,in which the graphite phase was already occured,formed in the dissolution region,They dissolved into the ...Melted cast iron was inoculated by FeSi,then quenched to interrupt the dissolution, the non-metallic inclusions,in which the graphite phase was already occured,formed in the dissolution region,They dissolved into the melt soon,but the inclusions coated by graphite could exist for along time.The function of inoculant is to create an undercooling solution for carbon,thereby the non-metallic inclusions in the solution may be activated as the nuclei for graphite.展开更多
This study will see the resurgence of interest in precise velocity dispersion measurements, both for the study of galactic and active nuclei kinematics. As several works suggest, an excellent tactic to measure σ is t...This study will see the resurgence of interest in precise velocity dispersion measurements, both for the study of galactic and active nuclei kinematics. As several works suggest, an excellent tactic to measure σ is to use the absorption lines of the calcium triplet, as it is a spectral region relatively free from complications. The discovery of an empirical relationship between the mass of the central black hole (M•) and σ was the leading guide of my detailed study of the calcium triplet region. This search for more accurate methods to calculate the dispersion of velocities, in addition to the careful study of uncertainties. After investing so much time in the development and improvement of the method and its application to so many galaxies, it is time to reap the rewards of this effort, using my results to address a series of questions concerning the physics of galaxies.展开更多
Ⅰ. INTRODUCTIONIRAS indicates the complication for the origin of the infrared radiation of Seyfert galaxies. Besides thermal and non-thermal radiation from the active nuclei, there are two important non-nuclear compo...Ⅰ. INTRODUCTIONIRAS indicates the complication for the origin of the infrared radiation of Seyfert galaxies. Besides thermal and non-thermal radiation from the active nuclei, there are two important non-nuclear components: contribution from cold material in the host galactic展开更多
The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST) provides an increase in sensitivity and has detected rapid variability of gamma-ray sources.The variability time scales detected f...The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST) provides an increase in sensitivity and has detected rapid variability of gamma-ray sources.The variability time scales detected from the gamma-ray loud blazars by LAT and EGRET,and gamma-ray luminosity are used to estimate the central black hole masses.In this work,we find that the lower limits of central black hole masses are in a range of (0.3-24)×107M⊙,which are compared with those obtained by other authors.Our results are consistent with other authors' results.Also,the Lorentz factor,Γ,and the propagation angle,θ,are obtained for 18 blazars for which superluminal motions are known.展开更多
Radio galaxies are divided into two groups according to their luminosities at 178 MHz, namely Fa- naroff-Riley type Is (FRIs) and Fanaroff-Riley type IIs (FRIIs) with FRIs showing lower radio luminosities than FRIIs. ...Radio galaxies are divided into two groups according to their luminosities at 178 MHz, namely Fa- naroff-Riley type Is (FRIs) and Fanaroff-Riley type IIs (FRIIs) with FRIs showing lower radio luminosities than FRIIs. In this paper, the X-ray data are compiled for 183 radio galaxies (61 FRIs and 122 FRIIs), from the available literature, for the analysis of the X-ray properties. The 1 keV X-ray luminosities are calculated and discussed for the two groups, and an averaged X-ray luminosity of logLX1 keV = 41.30±2.51 erg·s-1·keV-1 is found for FRIs, which is lower than that for FRIIs, logLX1 KeV = 43.39±3.06 erg·s-1·keV-1. A Kolmogorov-Smirnov (K-S) test indicates that the probability for the X-ray luminosity distributions of the two groups to be from the same parent distribution is 1.44×10-10. We also discuss the origin and the mechanism of the X-ray emission for FRIs and FRIIs.展开更多
We present the first Chandra X-ray observations of the H2O megamaser galaxy Mrk1210 (UGC4203), a Seyfert 2 galaxy at an approximate distance of D～57.6 Mpc. The Chandra X-ray image, with by far the highest angular res...We present the first Chandra X-ray observations of the H2O megamaser galaxy Mrk1210 (UGC4203), a Seyfert 2 galaxy at an approximate distance of D～57.6 Mpc. The Chandra X-ray image, with by far the highest angular resolution (～1"), displays an unresolved compact core toward the nuclear region of Mrk1210. Comparisons with the previous X-ray observations in the nuclear emission and the spectral shape indicate a fairly stable phase between 2001 (BeppoSAX and XMM-Newton) and 2004 (Chandra) after a dramatic variation since 1995 (ASCA). The best-fit model of Chandra X-ray spectrum consists of two components. The soft scattered component can be best fitted by a moderately absorbed power-law model adding a spectral line at ～0.9 keV (possibly a Ne-Kα fluorescent line), while the hard nuclear component can be well reproduced by a heavily absorbed power-law model (NH～2×1023 cm-2) with an additional line at ～6.19 keV (close to the Fe-Kα fluorescent line). The derived absorption-corrected X-ray luminosity implies that the dramatic variation of spectral properties is caused by significant changes of the absorbing column density along the line-of-sight, while the intrinsic nuclear X-ray lu-minosity remains stable. In this case, the absorbers should be anisotropic and its size can be constrained to be less than 0.0013 pc. In addition, we also estimate the mass of central engine, the disk radius and the accretion rate of the accretion disk to be 107.12±0.31M⊙, ～1 pc and 0.006, respectively.展开更多
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 morphology.It is one of four BL Lac objects with a kpc scale extended X-ray jet.In this pape...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 morphology.It is one of four BL Lac objects with a kpc scale extended X-ray jet.In this paper,we searched the unpublished European VLBI Network(EVN) archived high resolution data for this source,and present the high resolution radio structure.The EVN images all show a core-jet structure in 1.6,5 and 8 GHz.In combination with the VLA data in the literature,we found position angle differences(△PA) of about 10°-20° between pc and kpc scale jet structures.The 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 12.0.We 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.展开更多
文摘Melted cast iron was inoculated by FeSi,then quenched to interrupt the dissolution, the non-metallic inclusions,in which the graphite phase was already occured,formed in the dissolution region,They dissolved into the melt soon,but the inclusions coated by graphite could exist for along time.The function of inoculant is to create an undercooling solution for carbon,thereby the non-metallic inclusions in the solution may be activated as the nuclei for graphite.
文摘This study will see the resurgence of interest in precise velocity dispersion measurements, both for the study of galactic and active nuclei kinematics. As several works suggest, an excellent tactic to measure σ is to use the absorption lines of the calcium triplet, as it is a spectral region relatively free from complications. The discovery of an empirical relationship between the mass of the central black hole (M•) and σ was the leading guide of my detailed study of the calcium triplet region. This search for more accurate methods to calculate the dispersion of velocities, in addition to the careful study of uncertainties. After investing so much time in the development and improvement of the method and its application to so many galaxies, it is time to reap the rewards of this effort, using my results to address a series of questions concerning the physics of galaxies.
基金Project supported by the National Natural Science Foundation and Science Foundation of National Education Committee for Ph. D. Station
文摘Ⅰ. INTRODUCTIONIRAS indicates the complication for the origin of the infrared radiation of Seyfert galaxies. Besides thermal and non-thermal radiation from the active nuclei, there are two important non-nuclear components: contribution from cold material in the host galactic
基金supported by the National Natural Science Foundation of China (Grant Nos. 10573005 and 10633010)the National Basic Research Program of China (Grant No. 2007CB815405)+1 种基金Hunan Provincial Natural Science Foundation of China (Grant No. 10JJ3020)the Fund of the 11th Five-year Plan for Key Construction Academic Subject (Optics) of Hunan Province
文摘The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST) provides an increase in sensitivity and has detected rapid variability of gamma-ray sources.The variability time scales detected from the gamma-ray loud blazars by LAT and EGRET,and gamma-ray luminosity are used to estimate the central black hole masses.In this work,we find that the lower limits of central black hole masses are in a range of (0.3-24)×107M⊙,which are compared with those obtained by other authors.Our results are consistent with other authors' results.Also,the Lorentz factor,Γ,and the propagation angle,θ,are obtained for 18 blazars for which superluminal motions are known.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10573005 and 10633010)the National Basic Research Program of China (Grant No. 2007CB815405)
文摘Radio galaxies are divided into two groups according to their luminosities at 178 MHz, namely Fa- naroff-Riley type Is (FRIs) and Fanaroff-Riley type IIs (FRIIs) with FRIs showing lower radio luminosities than FRIIs. In this paper, the X-ray data are compiled for 183 radio galaxies (61 FRIs and 122 FRIIs), from the available literature, for the analysis of the X-ray properties. The 1 keV X-ray luminosities are calculated and discussed for the two groups, and an averaged X-ray luminosity of logLX1 keV = 41.30±2.51 erg·s-1·keV-1 is found for FRIs, which is lower than that for FRIIs, logLX1 KeV = 43.39±3.06 erg·s-1·keV-1. A Kolmogorov-Smirnov (K-S) test indicates that the probability for the X-ray luminosity distributions of the two groups to be from the same parent distribution is 1.44×10-10. We also discuss the origin and the mechanism of the X-ray emission for FRIs and FRIIs.
基金Supported by the National Natural Science Foundation of China (Grant No.10633010)the Natural Science Foundation of Guangdong Province,China (Grant No.8451009101001047) Recommended by Zhou YouYuan
文摘We present the first Chandra X-ray observations of the H2O megamaser galaxy Mrk1210 (UGC4203), a Seyfert 2 galaxy at an approximate distance of D～57.6 Mpc. The Chandra X-ray image, with by far the highest angular resolution (～1"), displays an unresolved compact core toward the nuclear region of Mrk1210. Comparisons with the previous X-ray observations in the nuclear emission and the spectral shape indicate a fairly stable phase between 2001 (BeppoSAX and XMM-Newton) and 2004 (Chandra) after a dramatic variation since 1995 (ASCA). The best-fit model of Chandra X-ray spectrum consists of two components. The soft scattered component can be best fitted by a moderately absorbed power-law model adding a spectral line at ～0.9 keV (possibly a Ne-Kα fluorescent line), while the hard nuclear component can be well reproduced by a heavily absorbed power-law model (NH～2×1023 cm-2) with an additional line at ～6.19 keV (close to the Fe-Kα fluorescent line). The derived absorption-corrected X-ray luminosity implies that the dramatic variation of spectral properties is caused by significant changes of the absorbing column density along the line-of-sight, while the intrinsic nuclear X-ray lu-minosity remains stable. In this case, the absorbers should be anisotropic and its size can be constrained to be less than 0.0013 pc. In addition, we also estimate the mass of central engine, the disk radius and the accretion rate of the accretion disk to be 107.12±0.31M⊙, ～1 pc and 0.006, respectively.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10633010, 10703009, 10833002 and 10821302)the National Basic Research Program of China (Grant No. 2009CB824800)+2 种基金the Study Abroad Fund from the Ministry of Education of China (Grant No. O922571001)the Science Foundation of Guizhou Province (Grant No. 20092064)the Science Foundation of Guizhou University (Grant No. 2008035)
文摘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 morphology.It is one of four BL Lac objects with a kpc scale extended X-ray jet.In this paper,we searched the unpublished European VLBI Network(EVN) archived high resolution data for this source,and present the high resolution radio structure.The EVN images all show a core-jet structure in 1.6,5 and 8 GHz.In combination with the VLA data in the literature,we found position angle differences(△PA) of about 10°-20° between pc and kpc scale jet structures.The 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 12.0.We 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.
文摘HADAR(High Altitude Detection of Astronomical Radiation)是一个基于大气切伦科夫成像技术的地面望远镜阵列,其采用大口径折射式水透镜系统来收集大气切伦科夫光,以实现对10 GeV—10 TeV能量段的伽马射线和宇宙线的探测.HADAR具有低阈能和大视场的优势,因此可以对天区进行连续扫描和观测,在观测活动星系核(Active Galactic Nuclei,AGN)等银河系外伽马射线源方面具有明显优势.本文研究了HADAR实验对AGN的探测能力.基于费米望远镜(Fermi Large Area Telescope,Fermi-LAT)的AGN源能谱信息,将观测能量外推至甚高能能段,同时加入河外背景光的吸收效应,以计算HADAR对AGN源观测的统计显著性.研究结果显示,HADAR运行一年时间,预计将有31个Fermi-LAT AGN源以高于5倍显著性被观测到,其中大部分为蝎虎状天体类型.
