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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 {2. and National astronomical Observatories, Chinese {4. of sciences, beijing 100012. beijing astronomical {2. and National astronomical Observatories 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 4. 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 38 out of the 4. 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

The 3-channel High-Speed Photometer at beijing astronomical {2.

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天文研究与技术 1999年第S1期 68-71页

作者： Jiang Xiaojun 1,2.1 beijing astronomical {2., The Chinese academy of {4., beijing 100012. china Email: xjjiang @ class1. bao. ac. cn 2.National astronomical Observatories, The Chinese academy of {4.

A 2.channel photometer was upgraded to a Whole Earth Telescope (WET) high speed 3 channel photometer at beijing astronomical {2. (BAO). The structure and functions of the photometer are discussed. The data obt...

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Vilnius Photometry and Reddening of the Young Open Cluster NGC 6913

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Chinese Journal of Astronomy and Astrophysics 2001年第4期1卷 333-343页

作者： Jun-Jie Wang and Jing-Yao Hu (National astronomical Observatories, Chinese academy of {2., beijing 100012.beijing astronomical observatory, Chinese academy of {2., beijing 100012.Chinese academy of {2.-Peking University Joint beijing As Chinese academy of sciences-Peking University Joint {2. Astrophysical Center Beijing 100871

stars in the NGC 6913 field with both UBV and Vilnius photometry are selected to be the sample. The membership probability of the stars is greater than 50%. The correlation among Vilnius photometry, UBV photometry and reddening in the cluster is reviewed. It is found that the photometry in the Vilnius X, Y and Z bands can be used to make rough spectral classification. The values of E(B - V) are well correlated with the Vilnius colors of X - Y, Y - Z, Z - V and V - S in NGC 6913. The ratio of (V - S)/(Y - Z) of the MPCM (Most Possible Cluster Members) is a constant (1.30 -±0.06), and has no effect on the values of E(B - V), (B - V)0 and V0. Comparing with the observational data of all the stars of NGC 6913 region, we propose that the value of (V - S)/(Y - Z) can probably be used to select the preliminary candidates of one open cluster. In addition, 12.variable stars are discovered in the NGC 6913 region, in which star #155 has a variation with an amplitude of 4.2. mag.

关键词： Galaxy: open clusters and associations - ISM: dust extinction

Entropy of three-dimensional BTZ black holes

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中国科学：物理学、力学、天文学英文版 2004年第3期47卷 277-283页

作者： GAO Changjun1,2.& SHEN Yougen1,2.3,4.1.Shanghai astronomical {2.,Chinese academy of sciences,Shanghai 2.0030,{4.(mailing address) 2.National astronomical Observatories,Chinese academy of sciences,beijing 100012.{4. 3.Institute of Theoretical Physics,Chinese academy of sciences,beijing 100080,{4. 4.Shanghai United Center for Astrophysics,Shanghai 2.02.4.{4. 1. Shanghai astronomical observatory Chinese Academy of Sciences 200030 Shanghai China 2. National astronomical Observatories Chinese Academy of Sciences 100012 Beijing China 3. Institute of Theoretical Physics Chinese Academy of Sciences 100080 Beijing China 4. Shanghai United Center for Astrophysics 200234 Shanghai China

The entropies of scalar field and neutrino field are calculated in the background of three-dimensional BTZ black hole. Considering statistical physics,we propose not to consider the superraradiant modes for bosons (Fermion fields do not display supperradiance).In fact,the nonsuperradiant modes do contribute exactly the area entropy for both bosons and fermions. The result shows that the neutrino field entropy is 3/2.times the scalar one.

关键词： BTZ black holes, entropy, supperradiant modes.

Time of impact of fragment P2.of comet SL 9 on Jupiter

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Chinese Science Bulletin 1997年第5期42卷 396-398页

作者： ZHOU Hongnan,QIAN Bochen, HUANG Keliang and LI Qibin1. Department of Astronomy, Nanjing University, Nanjing 2.0093, china 2. Shanghai observatory, Chinese {2. of sciences, Shanghai 2.0030, china 3. Physics Department, Nanjing Normal University, Nanjing 2.0097, china 4. beijing astronomical observatory, Chinese {2. of sciences, beijing 100080, china Department of Astronomy Nanjing University Nanjing China Shanghai observatory Chinese Academy of Sciences Shanghai China Physics Department Nanjing Normal University Nanjing China beijing astronomical {2. Chinese Academy of Sciences Behijing China

FROM 1994.07-16 to 1994.07-2., 2. fragments of comet SL 9 impacted against Jupiter in succession. During the impact period the impact of fragments D, E, K, N, P2.and S was observed in{2.. We used a 1.56-m telescope with the CCD camera of Shanghai observatory to monitor Jupiter and its Galilean Satellites, obtaining 1000 high-quality images at B, V, I wave bands. Our data on optical wave bands are rather complete and valuable in the world. Specially, we got some images of Jupiter, Io and Europa in the impact time of fragment P2.impacting against Jupiter. This will help us understand the precise time, position, depth and energy of the P2.s collision. In this note, we report the impact time of fragment P2.of comet SL 9 and Jupiter. Since the impact of comet SL 9 was expected to take place on the side of Jupiter

关键词： comet comet Shoemaker-Levy 9 impacting against Jupiter impact time.

PROGRESS ON SPACE SOLAR TELESCOPE

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空间科学学报 1998年第S1期18卷 5-11页

作者： AI Guo-xiang (beijing astronomical {2., The Chinese academy of {4., 100080)

The research of Space Solar Telescope is consisted of three aspects, the BalloonBorne and Ground-Mobile Solar Telescope which is a preparing project for the Space Solar Telescope, Space Solar Telescope and researches ... 详细信息

关键词： Solar telescope

A method to predict amplitude and date of maximum sunspot number

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Chinese Science Bulletin 2000年第14期45卷 1287-1290页

作者： HAN Yanbenbeijing astronomical {2., Chinese academy of {4., National astronomical Observatories, Chinese academy of {4., beijing 100012. china beijing astronomical {2. Chinese Academy of Sciences National Astronomical Observatories Chinese Academy of Sciences Beijing China

A method to predict the amplitude and date of the maximum sunspot number is introduced. The regression analysis of the relationship between the variation rate of monthly sunspot numbers in the initial stage of solar cycles and both of the maximum and the time-length of ascending period of the cycle showed that they are closely correlative. In general, the maximum will be larger and the ascending period will be shorter when the rate is larger. The rate of sunspot numbers in the initial 2.years of the 2.rd cycle is thus analyzed based on these grounds and the maximum of the cycle is predicted. For the smoothed monthly sunspot numbers, the maximum will be about 139.2.±18.8 and the time-length of ascending period will be about 3.31 ±0.4. years, that is to say, the maximum will appear around the spring of the year 2.00. For the mean monthly ones, the maximum will be near 170.1±2..9 and the time-length of ascending period will be about 3.4. ±0.4. years, that is to say, the appearing date of the maximum

关键词： solar activity prediction sunspot number 2.rd solar cycle.

Infrared Galaxies in the Nearby Universe

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Chinese Journal of Astronomy and Astrophysics 2008年第6期8卷 643-652页

作者： Jian-Ling Wang 1 National astronomical Observatories,Chinese academy of {2.,beijing 100012.{4. 2.Graduate School of Chinese academy of {2.,beijing 10004.,{4. National astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate School of Chinese academy of sciences Beijing 100049 China

We used the Sloan Digital Sky Survey （SDSS） Data Release 5 （DR5） to study the morphological properties of 1137 nearby infrared （IR） galaxies, most of which are brighter than 15.9 mag in r-band. This sample was drawn from a cross-correlation of the Infra-Red astronomical Satellite （IRAS） point source catalog redshift survey with DR5 at z ≤ 0.08. Based on this IR galaxy sample, we constructed five volume-limited sub-samples with IR luminosity ranging from 10^9.5 L⊙ to 10^12.⊙. By deriving the IR luminosity functions （LF） for different morphological types, we found that normal spiral galaxies are the dominant population below LIR ~ 8 ~ 10^10 L⊙; while the fraction of barred spiral galaxies increases with increasing IR luminosity and becomes dominant in spiral galaxies beyond LIR ≈ 5 × 10^10L⊙. As the IR luminosity decreases, the IR galaxies become more compact and have lower stellar masses. The analysis also shows that normal spiral galaxies give the dominant contribution to the total comoving IR energy density in the nearby universe, while, in contrast, the contribution from peculiar galaxies is only 39%.

关键词： galaxies evolution galaxies interactions galaxies starburst infrared galaxies galaxies luminosity function

Annual Modulation in Intraday Variability Timescales of Extragalactic Radio Sources

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Chinese Journal of Astronomy and Astrophysics 2001年第2期1卷 133-143页

作者： Shan-Jie Qian and Xi-Zhen Zhang (beijing astronomical {2., National astronomical Observatories, Chinese {4. of sciences, beijing 100012. beijing astronomical {2. National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

Annual modulations in timescales of intraday variability (IDV hereafter) are discussed for six extragalactic sources: 0716+714. 0917+62.0} 0954.65, 174.+70, 1803+78 and 2.07+77. The timescales calculated from scintillation theory are compared with the observational data . It is emphasized that systematic observations are required to identify the phenomenon and to determine the motion of the interstellar medium with respect to the Local Standard of Rest. In addition, significant deviations from the annual modulation could be due to intrinsic variations.

关键词： scattering - ISM: kinematics - BL Lacertae objects: individual: 0716+71 - quasars: individual: 0917+62.- radiation mechanisms: non-thermal