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Testing the Universality of the TIS Model on Cluster Scales from the X-ray Surface Brightness Profiles

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Chinese Journal of Astronomy and Astrophysics 2001年第1期1卷 29-38页

作者： Yu-Ying Zhang (beijing astronomical Observatory and {2., Chinese Academy of {3., beijing 100012) beijing astronomical Observatory and {2. Chinese Academy of Sciences Beijing 100012

The truncated isothermal sphere (TIS) model has been recently suggested as an alternative for virialized dark halos (Shapiro et al. 1999). Both its profound theoretical motivation and its successful explanations for the galactic rotation curves and the gravitational scaling laws of clusters indicate that the TIS model is a promising candidate among other prevailing models such as the NFW profile and the Burkert profile. This promotes us to re-examine the universality of the TIS model on cluster scales from a different angle. Using an ensemble of X-ray surface brightness profiles of 45 clusters, we test the goodness of fit of the TIS predicted gas distributions to the X-ray data under the assumption of isothermal, hydrostatic equilibrium. Unlike the conventional B model or the NFW/Burkert profile, for which about half of the clusters have the reduced X2.values smaller than 2. the TIS model fails in the fitting of the X-ray surface brightness profiles of clusters in the sense that 3. out of the 45 clusters show X2.> 2. This may constitute a challenge for the universality of the TIS model unless the present analysis is seriously contaminated by other uncertainties including the negligence of non-gravitational heating processes and the unconventional sampling of the X-ray data.

关键词： cosmology: theory -dark matter - galaxies: clusters: general- X-rays: galaxies

A Date Recovery System launched for chronological studies in ancient China

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Science China(Physics,Mechanics & Astronomy) 2008年第1期51卷 105-110页

作者： LI Yong national astronomical observatories,Chinese Academy of sciences,{2. {3.,China 1. national astronomical observatories Chinese Academy of Sciences Beijing 100012 China

Benefited from the performance of the Xia-Shang-Zhou Chronology Project(XSZP) in China and our new astronomical chronology method designed and processed for Chinese particular 60-day-cycle Ganzhi(the heavenly stems and earthly branches)date records,we launch a Date Recovery System(DRS)for ancient China. Of high analysis function,this software can recover and convert the complete or incomplete date information originally from Ganzhi style in the historical period of China to the Gregorian Calendar System,which may have wide applications in the area of literary history,archaeology and cultural relic,etc.,and solve the Goldbach Puzzles of Chinese *** an example,we give the detailed process for the sculptures on four bronze wares with the Ganzhi data and afterwards employ this software and provide their possible dates corresponding to Gregorian system.

关键词： chronology date ephemeris software

Thermal analysis of the baffle structure of the Solar Space Telescope

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Science China(Physics,Mechanics & Astronomy) 2010年第9期53卷 1755-1764页

作者： LI Rong1,2.3.& WANG Sen1,3.1 national astronomical observatories,Chinese Academy of sciences,{2. 100012,China 2.Graduate University of Chinese Academy of sciences,{2. 100049,China 3.Key Laboratory of Solar Activity,national astronomical observatories of Chinese Academy of sciences,{2. 100012,China 1. national astronomical observatories Chinese Academy of Sciences Beijing 100012 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Key Laboratory of Solar Activity National Astronomical Observatories of Chinese Academy of Sciences Beijing 100012 China

The SST(Space Solar Telescope) is an astronomical telescope with a primary mirror of 1 m in *** observes the sun with a small view field to ensure that its high spatial resolution imaging has 0.1″-0.15″ and high SNR(signal to noise ratio).Surrounding the small view field is still the sun,which is an intense source of both heat and stray *** baffles(the main baffle,the aperture,and the outer baffle),which are used to eliminate the stray light,will change the thermal flux in the SST and will weaken the effect of the thermal control *** this study,the compatibility analysis of the thermal effect of baffle structures in SST is *** GCF(Geometry Composing Function) and BRDF(Bidirectional Reflectance Distribution Function),which are two inherent related parameters in the compatibility analysis,are *** objective and method of the compatibility analysis are *** the thermal analysis software,the temperature fields are calculated for different lengths of the main baffle,different radii of apertures,different lengths of the outer baffle with a 3. tilt angle and 16' tilt angle,and different tilt angles of the outer baffle with a 2.0 mm length.A series of configurations and sizes of the baffles are studied with the goals of both thermal control and elimination of stray *** design of the baffle structure of SST is achieved:the main baffle of length 4100 mm,the internal shield of radius 494 mm,the outer baffle of length 2.0 mm,and the outer baffle of tilt angle 3. are successfully *** paper presents the relationship between the thermal control design and stray light elimination plan in the *** aims of the optimal design of the baffle structure of SST are *** thoughts and methods of the optimal analysis are also useful for similar optical telescopes designed for solar observation.

关键词： baffle the main baffle the outer baffle GCF BRDF

A Remark on Using Gravitational Lensing Probability as a Probe of the Central Regions of CDM Halos

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Chinese Journal of Astronomy and Astrophysics 2002年第5期2卷 399-407页

作者： YunLinational astronomical observatories, Chinese Academy of sciences,{2. national astronomical observatories Chinese Academy of Sciences Beijing 100012

We calculate the gravitational lensing probabilities by cold dark matter (CDM) halos with different density profiles, and compare them with current observations from the Cosmic Lens All-Sky Survey (CLASS) and the Jodrell-Bank VLA Astrometric Survey (JVAS). We find that the lensing probability is dramatically sensitive to the clumping of the dark matter, or quantitatively, the concentration parameter. We also find that our predicted lensing probabilities in most cases show inconsistency with the observations. It is argued that high lensing probability may not be an effective tool for probing the statistical properties of inner structures of dark matter halos.

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

Modeling earthquake indexes derived from the earthquake warning system upon the planet earth

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Science China(Physics,Mechanics & Astronomy) 2010年第12期53卷 2293-2299页

作者： LI Yong national astronomical observatories, Chinese Academy of sciences,{2., China 1. national astronomical observatories Chinese Academy of Sciences Beijing 100012 China

By studying the correlation between historical earthquake data and the distributional characteristics of parameters of solid earth tides in the earthquake epicenter, we are able to design a forecasting function of earthquake probability. We put forward a design method for the Earthquake Warning System. The model could theoretically simulate and be used to predict the probability of strong earthquakes that could occur anywhere at any time. In addition, the system could also conveniently obtain global or partial Modeling Earthquake Indexes to finally combine the precise pointing prediction and forecast of partial indexes. The literature quotes global data values, provided by NEIC, of 1544 M ≥ 6.5 earthquakes. It also gives examples of instantaneous earthquake indexes of the whole world and Taiwan Region on 1st January 2.10, UT=0:00 and the average earthquake index near the Taiwan Region. According to the 10-year pointing prediction of strong earthquakes in San Francisco, the literature provides the average earthquake index on 2.th June 2.15 (± 15 days), in its neighborhood.

关键词： earthquake earthquake warning system astrogeodynamics index

2.ASS photometry and age estimation of the globular clusters in the outer halo of M3.

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Research in Astronomy and Astrophysics 2012年第2期12卷 115-126页

作者： Jun Ma 1,2. national astronomical observatories,Chinese Academy of sciences,{2. 100012,China 2.Key Laboratory of Optical Astronomy,national astronomical observatories,Chinese Academy of sciences,{2. 100012,China national astronomical observatories Chinese Academy of Sciences Beijing 100012 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

We present the first photometric results in J, H and Ks from 2.ASS （Two Micron All Sky Survey） imaging of 10 classical globular clusters （GCs） in the far outer regions of M3.. Combined with the V and I photometric data from previous literature, we constructed a color-color diagram between J - Ks and V - Ⅰ. By comparing the integrated photometric measurements with evolutionary models, we estimate the ages of these clusters. The results showed that all of these clusters are older than 3.× 109 yr, and among them four are older than 10 Gyr and the other six have intermediate ages between 3.- 8 Gyr. The masses for these outer-halo GCs are from 7.0 × 104 M to 1.02.× 10^6 M. We argued that GC2.and GC3. whose ages, metallicities and distance moduli are almost the same, were accreted from the same satellite galaxy, if they did not form in situ. The statistical results show that the ages and metallicities of these 10 M3. outer-halo GCs do not vary with projected radial position, and a relationship between age and metallicity does not exist.

关键词： galaxies: halos - galaxies: individual (M3.) - star clusters: general

Planet Host Stars: Mass, Age and Kinematics

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Chinese Journal of Astronomy and Astrophysics 2002年第2期2卷 151-160页

作者： Yu-Qin Chen and Gang Zhao national astronomical observatories, Chinese Academy of sciences,{2. national astronomical observatories Chinese Academy of Sciences Beijing 100012

We determine the mass, age and kinematics of 51 extra-solar planet host stars. The results are then used to search for signs of connection of the data with metallicity and to investigate the population nature. We find that the increase in mean metallicity with stellar mass is similar to that in normal field stars, so it seems unsuitable to use this relation as a constraint on the theory of planet formation. The age and kinematic distributions seem to favour the metallicity of extra-solar planet host stars being initial. Although the kinematic data of these stars indicate their origin from two populations - the thin and the thick disks, kinematics may not help in the maintenance of the planet around the host. Stars with planets, brown dwarfs or stellar companions are sorted into three groups and re-investigated separately for their formation mechanism. The main results indicate that stars with M2.2.M3.have [Fe/H] > 0.1 and a wide period range, but there are no other differences. Thus, there does not seem to be any physically distinguishable characteristics among the three star groups.

关键词： stars: masses ages ─ stars: kinematics -planetary system

Vertical Scale Parameter Estimates for 48 Non-edge-on Spiral Galaxies

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Chinese Journal of Astronomy and Astrophysics 2003年第6期3卷 499-504页

作者： Jun Manational astronomical observatories, Chinese Academy of sciences,{2. national astronomical observatories CAS NAOC Beijing 100012 China

In the first paper of this series, we directly studied the mathematicalforms, symmetry of spiral structure, and the projection of galactic discs on the images, andmeasured the pitch angles of the spiral arms and inclination angles of the galactic discs for 60spiral galaxies. In this second paper, we estimate the vertical scale parameters of 48 non-edge-onspiral galaxies based on the method proposed by Peng et al. and on the results given in Paper I. Aswe know, for edge-on disc galaxies we can obtain the vertical scale parameter from the photometry,once a mathematical form is specified for the vertical light distribution. For non-edge-on galaxies,some other methods have to be used. The statistical result was that the vertical scale parameter iscomparable for edge-on and non-edge-on galaxies, although it is obtained from two very differentmethods.

关键词： galaxies: spiral galaxies galaxies: vertical scale parameter

The Amplitude of Mass Fluctuations and Mass Density of the Universe Constrained by Strong Gravitational Lensing

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Chinese Journal of Astronomy and Astrophysics 2004年第2期4卷 118-124页

作者： Da-Ming Chennational astronomical observatories, Chinese Academy of sciences,{2. cdm@*** national astronomical observatories Chinese Academy of Sciences Beijing 100012

We investigate the linear amplitude of mass fluctuations in the universe, σ8, and the present mass density parameter of the Universe, Ωm, from statistical strong gravitational lensing. We use the two population model of lens halos with fixed cooling mass scale Mc = 3.1013.-1M⊙ to match the observed lensing probabilities, and leave σ8 orΩm as a free parameter to be constrained by the data. Another varying parameter, the equation of state of dark energy ω, and its typical values of -1, -2.3. -1/2.and -1/3.are investigated. We find that σ8 is degenerate with Ωm in a way similar to that suggested by present day cluster abundance as well as cosmic shear lensing measurements: σ8Ω0.6m≈0.3.. However, both σ8≤0.7 and Ωm≤0.2.can be safely ruled out, the best fit is when σ8 = 1.0, Ωm = 0.3.and ω= - 1. This result is different from that obtained by Bahcall & Bode, who gave σ8 = 0.98±0.1 and Ωm = 0.17 ±0.05. For σ8 = 1.0, the higher value ofΩm = 0.3. requires ω = -2.3.and Ωm = 0.40 requires ω= -1/2.

关键词： cosmology: theory - cosmological parameters - gravitational lensing