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Chinese Journal of Astronomy and Astrophysics 2001年第1期1卷 39-45页

作者： You－JunLu Chong－ShanZhao centerforastrophysics UniversityofScienceandTechnologyofChinaHefei230026 centerforastrophysics Unive

We report on our research on the UV, optical line parameters and the infrared through UV to soft X-ray continuum parameters for a composite sample of narrow line and normal Seyfert 1 galaxies. The strong correlations among the line width of HB, optical line strength of Fell and the soft X-ray slope are confirmed. We found no correlations between the UV line parameters, the equivalent widths of Lya and CIV and their ratio on one hand and the optical line parameters on the other. The UV and X-ray luminosities strongly correlate with the line widths of HB and the Fe II/HB ratio. No significant correlation is found between the infrared-soft X-my continuum slope aix and the line width of HB.

关键词： galaxies: active galactic nuclei (AGN) - emission lines - Ultraviolet: galaxies - galaxies: X-rays

The Hybrid Nature of 0846+51W1: a BL Lac Object with a Narrow Line Seyfert 1 Nucleus

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Chinese Journal of Astronomy and Astrophysics 2005年第1期5卷 41-48页

作者： Hong-YanZhou Ting-GuiWang Xiao-BoDong ChengLi Xue-GuangZhang centerforastrophysics UniversityofScienceandTechnologyofChinaHefei230026

We found a NLS1 nucleus in the extensively studied eruptive BL Lac object, 0846+51W1, out of a large sample of NLS1s compiled from the spectroscopic dataset of SDSS DR1. Its optical spectrum can be well decomposed into three components: a power law component from the relativistic jet, a stellar component from the host galaxy, and a component from a typical NLS1 nucleus. The emission line properties of 0846+51W1, FWHM (Hβ) (?) 1710 km s-1 and [OⅢ]λ5007/Hβ(?)0.32 from its SDSS spectrum observed when it was in the faint state, fulfil the conventional definition of NLS1. Strong Fell emission is detected in the SDSS spectrum, which is also typical of NLS1s. We tried to estimate its central black hole mass using various techniques and found that 0846+51W1 is very likely emitting at a few ×10% of the Eddington luminosity. We speculate that Seyfert-like nuclei, including NLS1s, might be concealed in a significant fraction of BL Lacs but have remained largely unobserved because, often, their optical-UV continuum is overwhelmed by the synchrotron emission.

关键词： galaxies: active - galaxies: Seyfert - galaxies: BL Lacertae - quasars: indevidual (0846+51W1) - radiation: lines continuum

Global Axisymmetric Stability Analysis for a Composite System of Two Gravitationally Coupled Scale-Free Discs

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Chinese Journal of Astronomy and Astrophysics 2004年第6期4卷 541-552页

作者： YueShen Yu-QingLou DepartmentofPhysics＆centerforastrophysics TsinghuaUniversityBeijing100084 DepartmentofPhysics＆centerforastrophysics TsinghuaUniversityBeijing100084／／NationalAstronomicalObservatoriesChineseAcademyofSciencesBeijing100012

For a composite system of gravitationally coupled stellar and gaseous discs, we have carried out a linear stability analysis for axisyrnmetric coplanar perturbations using the two-fluid formalism. The background stellar and gaseous discs are taken to be scale-free with all physical variables varying as powers of the cylindrical radius r with compatible exponents. The unstable modes set in as neutral modes or stationary perturbation configurations with angular frequency f33 = 0. The axisyrnmetric stable range is bounded by two marginal stability curves derived from stationary perturbation configurations. Because of the gravitational coupling between the stellar arid the gaseous discs, one only needs to consider the parameter regime of the stellar disc. There exist two unstable regimes in general: a collapse regime corresponding to large-scale perturbations and a ring-fragmentation regime corresponding to short-wavelength perturbations. The composite system will collapse if it rotates too slowly and will succumb to ring-fragmentation instabilities if it rotates sufficiently fast. The overall stable range against axisyrnmetric perturbations is determined by a necessary D-criterion involving the effective Mach number squared Ds2 (the squared ratio of the stellar disc rotation speed to the stellar velocity dispersion up to a numerical factor). Different mass ratio S and sound speed ratio η of the gaseous and stellar disc components will alter the overall stability. For spiral galaxies or circumnuclear discs, we further include the dynamical effect of a massive dark matter halo. Astrophysical applications to disc galaxies, proto-stellar discs and circumnuclear discs are given as examples.

关键词： hydrodynamics - ISM: general - galaxies: kinematics and dynamics - galaxies: spiral - galaxies: structure - waves

Timescale Analysis of Spectral Lags

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Chinese Journal of Astronomy and Astrophysics 2004年第6期4卷 583-598页

作者： Ti-PeiLi Jin-LuQu HuaFeng Li-MingSong Guo-QiangDing LiChen ParticleAstrophysicsLab. InstituteofHighEnergyPhysicsChineseAcademyofSciences DepartmentofPhysics＆centerforastrophysics TsinghuaUniversityBeijing100084／／ParticleAstrophysicsLab.InstituteofHighEnergyPhysicsChineseAcademyofSciences DepartmentofEngineeringPhysics＆centerforastrophysics TsinghuaUniversity DepartmentofAstronomy BeijingNormalUniversity

A technique for timescale analysis of spectral lags performed directly in the time domain is developed. Simulation studies are made to compare the time domain technique with the Fourier frequency analysis for spectral time lags. The time domain technique is applied to studying rapid variabilities of X-ray binaries and γ-ray bursts. The results indicate that in comparison with the Fourier analysis the timescale analysis technique is more powerful for the study of spectral lags in rapid variabilities on short time scales and short duration flaring phenomena.

关键词： methods data analysis binaries general x-rays stars gamma rays bursts x-rays bursts

A DWT Power Spectrum Analysis of PSCz Galaxies

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Chinese Journal of Astronomy and Astrophysics 2001年第3期1卷 200-212页

作者： Yiao－HuYang Long－LongFeng 等 centerforastrophysics UniversityofScienceandTechnologyofChinaHeifei230026 NationalAstronomicalObserv

The power spectrum estimator based on the Discrete Wavelet Transfor- mation (DWT) is applied to detect the clustering power in the IRAS Point Source Catalog Redshift Survey (PSCz). Comparison with mock samples extracted from N-body simulation shows that the DWT power spectrum estimator could provide a robust measurement of banded fluctuation power over a range of wavenumbers 0.1 ~ 2.0hMpc-1. We have fitted three typical CDM models (SCDM, τCDM and CDM) using the Peacock-Dodds formula including non-linear evolution and redshift distortion. We find that, our results are in good agreement with other statistical measurements of the PSCz.

关键词： large-scale structure of Universe - Methods: N-body simulations

Mass-Temperature Relation of X-ray Clusters in Triaxial Halo

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Chinese Journal of Astronomy and Astrophysics 2004年第2期4卷 105-117页

作者： RongYang JunYu Guo-PengShen centerforastrophysics UniversityofScienceandTechnologyofChinaHefei230026／NationalAstronomicalObservatoriesChineseAcademyofScienceBeijing100012

We investigate the mass-temperature relation of clusters for both the spherical NFW halo model and a concentric triaxial halo model. We study the temperature and density distributions of both an isothermal and a polytropic intra-cluster gas in hydrostatic equilibrium. We find that both the uncertainties in the concentration parameter and in the eccentricities (in case of the triaxial halo) lead to a greater scatter in the emission-weighted temperature at a given halo mass for less massive clusters. This may be helpful when determining the intrinsic statistical error of the σ8 normalization of the linear power spectrum from cluster abundance.

关键词： cosmology: theory galaxy: cluster: general large-scale structure ofuniverse

Rhombic Cell Analysis. Ⅱ. Application to the IRAS/PSCz Catalogue

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Chinese Journal of Astronomy and Astrophysics 2004年第3期4卷 209-220页

作者： TaoKiang Yong-FengWu Xing-FenZhu DunsinkObservatory DublinInstituteforAdvancedStudiesDublin15Ireland centerforastrophysics UniversityofScienceandTechnologyofChinaHefei230026

Rhombic cell analysis as outlined in the first paper of the present series is applied to samples of varying depths and liming luminosities of the IRAS/PSCz Catalogue. Numerical indices are introduced to summarize essential information. Because of the discrete nature of the analysis and of the space distribution of galaxies, the indices for a given sample must be regarded as each having an irreducible scatter. Despite the scatter, the mean indices show remarkable variations across the samples. The underlying factor for the variations is shown to be the limiting luminosity rather than the sampling depth. As samples of more and more luminous galaxies are considered over a range of some 2.5 magnitudes (a factor of some 75 in space density), the morphology of the filled and empty regions defined by the galaxies degrades steadily towards insignificance, and the degrading is faster for the filled than the empty region.

关键词： cosmology: large-scale structure of universe cosmology: observations IRAS/PSCz catalogue

Corrected Stefan-Boltzmann Law and Lifespan of a Black Hole

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Chinese Physics Letters 2014年第8期31卷 1-3页

作者：何唐梅杨锦波张靖仪 LaboratoryCenter GuangzhouUniversityGuangzhou510006 centerforastrophysics GuangzhouUniversityGuangzhou510006

The corrected Stefan-Boltzmann law of black holes in the frame of a generalized uncertainty principle is derived through the Planck equation of thermal radiation. The result is different from the fiat spacetime： a corrected T term induced by the generalized uncertainty principle emerges; the coefficient of the T4 term is no longer a constant while related with the spacetime in the vicinity of the event horizon and the thin film model. Applying this corrected law to black hole radiation, the highest temperature in the final time of the radiation and the corresponding remnant with a mass of order of Planck mass are obtained. The lifespan of black holes is also corrected, however, the correction is extremely small.

关键词： Radiation Black holes

Chandra Observations of the Flat Spectrum Seyfert-2 Galaxies NGC 2110 and NGC 7582

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Chinese Journal of Astronomy and Astrophysics 2004年第5期4卷 427-439页

作者： HuiDong Sui-JianXue ChengLi Fu-ZhenCheng centerforastrophysics UniversityofScienceandTechnologyofChinaHefei230026 NationalAstronomicalObservatories ChineseAcademyofSciencesBeijing100012

Chandra observations of the Seyfert-2 galaxies NGC 2110 and NGC 7582 arepresented. With the superb spatial resolution of Chandra we found that in NGC 7582 the soft (≤2keV) and hard (2-10 keV) X-rays are emitted in different regions, consistent with the report by Xueet al. By comparing the present X-ray data with the previous infrared data, we determined that thesoft X-ray region is the site of starburst activities. We found no significant temporal variationsduring our observations. We confirm the previous finding that NGC 2110 and NGC 7582 areflat-spectrum sources. We argue that the flat spectra may result from a cold absorbing material suchas envisaged in the 'dual absorbed' model. Strong FeK_α emission feature is detected in 6～*** equivalent width is so large that it cannot be reproduced by using the Galactic column densityof ～ 10^(22) cm^(-2).

关键词： X-rays: image X-ray: spectrum galaxy: seyfert galaxy: individuals

The Correlation between Gamma-ray and Radio Emissions in γ-ray Loud Blazars

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Chinese Journal of Astronomy and Astrophysics 2005年第3期5卷 229-237页

作者： Jiang-HeYang Jun-HuiFan DepartmentofPhysicsandElectronicsScience HunanUniversityofArtsandScienceChangde415000／／CenterforAstrophysicsGuangzhouUniversityGuangzhou510405 centerforastrophysics GuangzhouUniversityGuangzhou510405／／NationalAstronomicalObservatoriesChineseAcademyofSciencesBeijing100012／／PhysicsInstituteHunanNormalUniversityChangsha410081

We collect 119 γ-ray-loud blazars (97 flat spectrum radio quasars (FSRQs) and 22 BL Lacertae objects (BL Lacs)), and investigate possible correlations between their γ-ray emission (maximum, minimum and average values) at 1 GeV and the radio emission at 8.4 GHz. Our main results are as follows. For the lower state γ-ray data, there is no correlation between the γ-ray and radio flux density; For the high state γ-ray data, there are good correlations for the whole 119 blazars and 97 FSRQs, and a weak correlation for the 22 BL Lac objects; For the average γ-ray data, there are good correlations. According to our analysis, we propose that the γ-rays are associated with the radio emission from the jet, and that the γ-ray emission is likely from the SSC process in this case.

关键词： Galaxies: active - BL Lacertae objects- quasars