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Model fitting of the kinematics of ten superluminal components in blazar 3C 279

Research in Astronomy and Astrophysics 2013年第7期13卷 783-802页

作者： Shan-Jie Qian national astronomical observatories Chinese Academy of Sciences

The kinematics of ten superluminal components （C11-C16, C18, C20, C21 and C24） of blazar 3C 279 are studied from VLBI observations. It is shown that their initial trajectory, distance from the core and apparent speed can be well fitted by the precession model proposed by Qian. Combined with the results of the model fit for the six superluminal components （C3, C4, C7a, C8, C9 and C10） already pub-lished, the kinematics of sixteen superluminal components can now be consistently interpreted in the precession scenario with their ejectiontimes spanning more than 25 yr （or more than one precession period）. The results from model fitting show the possible existence of a common precessing trajectory for these knots within a pro- jected core distance of ～0.2-0.4 mas. In the framework of the jet-precession scenario, we can, for the first time, identify three classes of trajectories which are character-ized by their collimation parameters. These different trajectories could be related to the helical structure of magnetic fields in the jet. Through fitting the model, the bulk Lorentz factor, Doppler factor and viewing angle of these knots are derived. It is found that there is no evidence for any correlation between the bulk Lorentz factor of the components and their precession phase （or ejection time）. In a companion paper, the kinematics of another seven components （C5a, C6, C7, C17, C19, C22 and C23） have been derived from model fitting, and a binary black-hole/jet scenario was envisaged. The precession model proposed by Qian would be useful for understanding the kine- matics of superluminal components in blazar 3C 279 derived from VLBI observations, by disentangling different mechanisms and ingredients. More generally, it might also be helpful for studying the mechanism of jet swing （wobbling） in other blazars.

关键词： radio continuum - galaxies jets - galaxies kinematics - galaxies individual (blazar 3C 279)

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A New Catalogue of Fine Structures Superimposed on Solar Microwave Bursts

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Chinese Journal of Astronomy and Astrophysics 2004年第2期4卷 176-188页

作者： Qi-Jun Fu, Yi-Hua Yan, Yu-Ying Liu, Min Wang and Shu-Juan Wangnational astronomical observatories, Chinese Academy of Sciences, Beijing 100012 fuqijun2002@*** national astronomical observatories Chinese Academy of Sciences Beijing 100012

The 2.6-3.8 GHz, 4.5-7.5 GHz, 5.2-7.6 GHz and 0.7-1.5 GHz componentspectrometers of Solar Broadband Radio Spectrometer (SBRS) started routine observations,respectively, in late August 1996, August 1999, August 1999, and June 2000. They just managed tocatch the coming 23rd solar active maximum. Consequently, a large amount of microwave burst datawith high temporal and high spectral resolution and high sensitivity were obtained. A variety offine structures (FS) superimposed on microwave bursts have been found. Some of them are known, suchas microwave type Ⅲ bursts, microwave spike emission, but these were observed with more detail;some are new. Reported for the first time here are microwave type U bursts with similar spectralmorphology to those in decimetric and metric wavelengths, and with outstanding characteristics suchas very short durations (tens to hundreds ms), narrow bandwidths, higher frequency drift rates andhigher degrees of polarization. Type N and type M bursts were also observed. Detailed zebra patternand fiber bursts at the high frequency were found. Drifting pulsation structure (DPS) phenomenaclosely associated with CME are considered to manifest the initial phase of the CME, andquasi-periodic pulsation with periods of tens ms have been recorded. Microwave 'patches', unlikethose reported previously, were observed with very short durations (about 300 ms), very high fluxdensities (up to 1000 sfu), very high polarization (about 100% RCP), extremely narrow bandwidths(about 5%), and very high spectral indexes. These cannot be interpreted with the gyrosynchrotronprocess. A superfine structure in the form of microwave FS (ZPS, type U), consisting of microwavemillisecond spike emission (MMS), was also found.

关键词： sun: flares sun: radio radiation instrumentation: spectro-graphs

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The clustering of QSOs and the dark matter halos that host them

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Research in Astronomy and Astrophysics 2013年第10期13卷 1141-1154页

作者： Dong-Yao Zhao Chang-Shuo Yan Youjun Lu national astronomical observatories Chinese Academy of Sciences

The spatial clustering of QSOs is an important measurable quantity which can be used to infer the properties of dark matter halos that host *** construct a simple QSO model to explain the linear bias of QSOs measured by recent observations and explore the properties of dark matter halos that host a *** assume that major mergers of dark matter halos can lead to the triggering of QSO phenomena,and the evolution of luminosity for a QSO generally shows two accretion phases,i.e.,initially having a constant Eddington ratio due to the self-regulation of the accretion process when supply is sufcient,and then declining in rate with time as a power law due to either diminished supply or long term disk *** a Markov Chain Monte Carlo method,the model parameters are constrained by fitting the observationally determined QSO luminosity functions（LFs）in the hard X-ray and in the optical band *** the model parameters that best fit the QSO LFs,the linear bias of QSOs can be predicted and then compared with the observational measurements by accounting for various selection efects in diferent QSO *** find that the latest measurements of the linear bias of QSOs from both the SDSS and BOSS QSO surveys can be well *** typical mass of SDSS QSOs at redshift 1.5

关键词： black hole physics galaxies:active cosmology

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A Gravitational Wave Background from Primordial Black Hole Lattices in Matter Dominated Era

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Communications in Theoretical Physics 2019年第10期71卷 1196-1204页

作者： Ke Wang national astronomical observatories Chinese Academy of Sciences

We use the wide-used Einstein Toolkit to solve the Einstein constraints and then simulate the expansion of primordial black hole lattices(PBHLs) with different value of f PBH and m PBH. We find that f PBH plays an important role during the evolution of PBHLs. Since the motion of primordial black holes(PBHs) caused by the expansion of PBHLs occurs at speeds close to that of light, we expect the emission of gravitational waves(GWs) during the expansion of PBHLs. We use both analytical estimates and numerical simulations to cross check the production of GWs in expanding PBHLs.

关键词： Einstein Toolkit primordial black hole lattices gravitational waves

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Cross-correlation of 21 cm and soft X-ray backgrounds during the epoch of reionization

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Research in Astronomy and Astrophysics 2016年第8期16卷 135-144页

作者： Jun-Min Liang Xiao-Chun Mao Bo Qin national astronomical observatories Chinese Academy of Sciences

The cross-correlation between the high-redshift 21 cm background and the Soft X-ray Background （SXB） of the Universe may provide an additional probe of the Epoch of Reionization. Here we use semi-numerical simulations to create 21 cm and soft X-ray intensity maps and construct their cross power spectra. Our results indicate that the cross power spectra are sensitive to the thermal and ionizing states of the intergalactic medium （IGM）. The 21 cm background correlates positively to the SXB on large scales during the early stages of the reionization. However as the reionization develops, these two back- grounds turn out to be anti-correlated with each other when more than - 15% of the IGM is ionized in a warm reionization scenario. The anti-correlated power reaches its maximum when the neutral fraction declines to 0.2-0.5. Hence, the trough in the cross power spectrum might be a useful tool for tracing the growth of HII regions during the middle and late stages of the reionization. We estimate the detectability of the cross power spectrum based on the abilities of the Square Kilometre Array and the Wide Field X-ray Telescope （WFXT）, and find that to detect the cross power spectrum, the pixel noise of X-ray images has to be at least 4 orders of magnitude lower than that of the WFXT deep survey.

关键词： cosmic background radiation -- cosmology: theory -- dark ages reionization first stars --early Universe -- diffuse radiation -- X-rays: diffuse background

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Mass to light ratio of galaxies and gravitational lensing

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Research in Astronomy and Astrophysics 2013年第9期13卷 1041-1051页

作者： Nan Li Ran Li Xin-Zhong Er national astronomical observatories Chinese Academy of Sciences

We investigate the potential of constraining the mass to light ratio of field galaxies using weak lensing shear and flexions. A suite of Monte Carlo simulations are used to generate weak lensing observations with different noise models. Using mock data, we find that the inclusion of flexions can improve the estimate of foreground halo parameters, but the details are strongly dependent on noise in the model. In the intrinsic noise limit, both shear and flexions are promising tools to study the mass to light ratio of galaxies. However, if the noise model of flexions follows the form described by Rowe et al., there is only - 5% improvement in the constraints even with next generation lensing observations.

关键词： cosmology: dark matter -- galaxies: halos -- gravitational lensing

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A Quasi-Periodic Solar Radio Fluctuation at Microwave Band

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Chinese Physics Letters 2005年第12期22卷 3229-3232页

作者：许富英黄光力吴洪敖 Purple Mountain observatory Chinese Academy of Sciences Nanjing 210008 national astronomical observatories Chinese Academy of Sciences Beijing 100012

A rare but interesting solar radio fine structure, quasi-periodic fluctuations, on 25 August 1999 was observed at microwave band for the first time. They fluctuated initially at a nearly stable frequency level then at a reverse drift component up to 5.49 GHz, The individual fluctuation consists of a hi-directional drift component. The features are characterized by narrow bandwidth of △f/f≤3%, quasi-periodicity of ～ 100 ms as well as a slowly reverse and a rapidly normal drift rates on the hi-directional drift component. The associated data of the Yohkoh soft and hard x-ray telescope and Nobeyama radio heliograph at 17GHz showed that there are several bright spots （i.e. inhomogeneities） along the soft x-ray loop, and the locations of both radio and soft x-ray sources are closely consistent. Therefore, the fluctuations are most likely caused by the inhomogeneities within a flare loop. Based on the two-component atmospheric model, we suggest a three-component atmospheric model with large scale length λ and small scale lengths λ1 and λ2 to describe equilibrium atmosphere and inhomogeneity. With the beam model, the characters of fluctuations may be interpreted reasonably by the quasi-equidistant inhomogeneity along a flare loop.

关键词： LOW CORONA FLARE DRIFT

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Exploration of Galactic γ-ray supernova remnants

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Science China(Physics,Mechanics & Astronomy) 2013年第8期56卷 1443-1453页

作者： TIAN WenWu ZHANG JianLi national astronomical observatories Chinese Academy of Sciences

New generational very-high-energy telescope arrays have been detecting more than 120 TeV γ-ray sources. Multi-wavelength observations on these z-ray sources have proven to be robust in shedding light on their nature. The coming radio telescope arrays like ASKAP and FAST may find more faint （extended） radio sources due to their better sensitivities and resolutions, might identify more previously un-identified γ-ray sources and set many new targets for future deep surveys by very-highenergy ground-based telescopes like LHAASO. We in the paper summarize a list of known Galactic γ-ray Supernova Remnants （SNRs） with or without radio emissions so far, which includes some SNRs deserving top priority for future multi-wavelength observations.

关键词： supernova remnants γ-ray sources cosmic rays

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Influence of σ^(* )and φ Mesons on (A) Hyperon ^(1)S_(0) Superfluidity in Neutron Star Matter

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Chinese Physics Letters 2012年第5期29卷 252-255页

作者： XU Yan LIU Guang-Zhou WANG Hong-Yan DING Wen-Bo ZHAO En-Guang changchun observatory National Astronomical ObservatoriesChinese Academy of SciencesChangchun 130117 Center for Theoretical Physics Jilin UniversityChangchun 130012 Department of Physics Bohai UniversityJinzhou 121000 Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190

Within the framework of the relativistic mean field theory,we investigate the ^(1)S_(0) superfluidity (SF) of A hyperons in neutron star (NS) matter including σ^(*) and φ *** energy gap of ∧ hyperons is calculated with the Nijmegen one-boson-exchange potentials for a (∧∧) pair. The parameter set we use is in line with the recent experimental data △B_(∧∧) ~ 1.01 ± 0.20_+0.18-0.11 *** is found that with σ^(*) and φ mesons the pairing energy gap △F of ∧ hyperons and the corresponding SF critical temperature T_(C∧) are *** addition the NS mass range of ∧ hyperon SF is enlarged obviously.

关键词： meson relativistic addition

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Properties of the UCHII region G25.4NW and its associated molecular cloud

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Research in Astronomy and Astrophysics 2013年第8期13卷 935-944页

作者： Mei Ai Ming Zhu Li Xiao Hong-Quan Su national astronomical observatories Chinese Academy of Sciences

Ultra compact HII （UCHII） G25.4NW is a bright IR source in the region of the inner Galaxy. New HI images from the Very Large Array Galactic Plane Survey show clear absorption features associated with the UCHII region up to 95 km s^-1, and there are no other absorptions up to the tangential velocity. This reveals that G25.4NW has a near-side distance of 5.7 kpc, and it is located in the region of the inner Galactic molecular ring. Using the new distance, the bolometric luminosity of G25.4NW is estimated as 105.6 L⊙, which corresponds to an 06 star. It contains 460 M⊙ of ionized gas. A high-resolution ^13CO image from the Galactic Ring Survey reveals that G25.4NW is part of a more extended star-forming complex with about 104 M⊙ of molecular gas.

关键词： radiation mechanisms: thermal - ISM: atoms - ISM: HII regions - ISM: molecules

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