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Circular Polarization in Pulsar Integrated Profiles: Updates

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Chinese Journal of Astronomy and Astrophysics 2006年第2期6卷 237-246页

作者： Xiao-Peng You jin-lin han National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

We update the systematic studies of circular polarization in integrated pulse profiles by han et al. Data of circular polarization profiles are compiled. Sense reversals can occur in core or cone components, or near the intersection between components. The correlation between the sense of circular polarization and the sense of position angle variation for conal-double pulsars is confirmed with a much large database. Circular polarization of some pulsars has clear changes with frequency. Circular polarization of millisecond pulsars is marginally different from that of normal pulsars.

关键词： polarization - pulsars: general

Spectral indices for radio emission of 228 pulsars

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Research in Astronomy and Astrophysics 2016年第10期16卷 81-92页

作者： Jun han Chen Wang Jun Xu jin-lin han National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China School of Astronomy University of Chinese Academy of Sciences Beijing 100049 China

We determine spectral indices of 228 pulsars by using Parkes pulsar data observed at 1.4 GHz, among which 200 spectra are newly determined. The indices are distributed in the range from -4.84 to -0.46. Together with known pulsar spectra from literature, we tried to find clues to the pulsar emission process. The wealCcorrelations between the spectral index, the spin-down energy loss rate E and the poten- tial drop in the polar gap Aψ hint that emission properties are related to the particle acceleration process in a pulsar＇s magnetosphere.

关键词： pulsars: general -- radiation mechanisms: general -- radio continuum: general

Lensing clusters of galaxies in the SDSS-Ⅲ

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Research in Astronomy and Astrophysics 2011年第10期11卷 1185-1198页

作者： Zhong-Lue Wen jin-lin han Yun-Ying Jiang National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

We identify new strong lensing clusters of galaxies from the Sloan Digital Sky Survey Ⅲ （SDSS DR8） by visually inspecting color images of a large sample of clusters of galaxies. We find 68 new clusters showing giant arcs in addition to 30 known lensing systems. Among 68 cases, 13 clusters are ＂almost certain＂ lensing systems with tangential giant arcs, 22 clusters are ＂probable＂ and 31 clusters are ＂pos- sible＂ lensing systems. We also find two exotic systems with blue rings. The giant arcs have angular separations of 2.0jj - 25.7j~ from the bright central galaxies. We note that the rich clusters are more likely to be lensing systems and the separations between the arcs and the central galaxies increase with cluster richness.

关键词： galaxies clusters general -- gravitational lensing

Estimating Black Hole Masses of AGNs using Ultraviolet Emission line Properties

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Chinese Journal of Astronomy and Astrophysics 2006年第4期6卷 396-410页

作者： Min-Zhi Kong Xue-Bing Wu Ran Wang jin-lin han National Astronomical Observatories Chinese Academy of Sciences Beiiing 1000121 Department of Astronomy Peking University Beijing 100871

Based on measured broad line region sizes in the reverberation-mapping AGN sample, two new empirical relations are introduced to estimate the central black hole masses of radio-loud high-redshift （z 〉 0.5） AGNs. First, using the archival IUE/HST spectroscopy data at UV band for the reverberation-mapping objects, we obtained two new empirical relations between the BLR size and Mg Ⅱ/C Ⅳ emission line luminosity. Secondly, using the newly determined black hole masses of the reverberation-mapping sample as calibration, we found two new relationships for determining the black hole mass with the full width at half maximum and the luminosity of Mg Ⅱ/C Ⅳ line. We then apply the relations to estimate the black hole masses of the AGNs in the Large Bright Quasar Survey and a sample of radio-loud quasars. For the objects with small radio-loudness, the black hole mass estimated using the RBLR-LMg Ⅱ/C Ⅳ relation is consistent with that from the RBLR-L3000 A/1350 A relation. For radio-loud AGNs, however, the mass estimated from the RBLR-LMg Ⅱ/C Ⅳ relation is systematically lower than that from the continuum luminosity L3000 A/13S0 A Because jets could have significant contributions to the UV/optical continuum luminosity of radio-loud AGNs, we emphasize once again that for radio-loud AGNs, the emission line luminosity may be a better tracer of the ionizing luminosity than the continuum luminosity, so that the relations between the BLR size and UV emission line luminosities should be used to estimate the black hole masses of high redshift radio-loud AGNs.

关键词： galaxies: nucleus -- galaxies: high-redshift-- quasars: emission lines -- ultraviolet: galaxies

Ionized gas clouds near the Sagittarius Arm tangent

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Research in Astronomy and Astrophysics 2017年第5期17卷 91-106页

作者： Li-Gang Hou Jian Dong Xu-Yang Gao jin-lin han National Astronomical Observatories Chinese Academy of Sciences Shanghai Astronomical Observatory Chinese Academy of Sciences

Radio recombination lines（RRLs） are the best tracers of ionized gas. Simultaneous observations of multi-transitions of RRLs can significantly improve survey sensitivity. We conducted pilot RRL observations near the Sagittarius Arm tangent by using the 65-m Shanghai Tian Ma Radio Telescope（TMRT） equipped with broadband feeds and a digital backend. Six hydrogen RRLs（H96α-H101α）at C band（6289 MHz-7319 MHz） were observed simultaneously toward a sky area of 2°× 1.2° by using on-the-fly mapping mode. These transitions were then stacked together for detection of ionized gas. Star forming complexes G48.6＋0.1 and G49.5-0.3 were detected in the integrated intensity *** found agreements between our measured centroid velocities and previous results for the 21 known HII regions in the mapped area. For more than 80 cataloged HII region candidates without previous RRL measurements, we obtained new RRL spectra at 30 targeted positions. In addition, we detected 25 new discrete RRL sources with spectral S/N 〉 5σ, and they were not listed in the catalogs of previously known HII regions. The distances for 44 out of these 55 new RRL sources were estimated.

关键词： tangent recombination listed transitions positions targeted pilot complexes toward FWHM

Braking PSR J1734–3333 with a possible fall-back disk

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Research in Astronomy and Astrophysics 2014年第1期14卷 85-92页

作者： Xiong-Wei Liu Ren-Xin Xu Guo-Jun Qiao jin-lin han Hao Tong School of Physics China West Normal University School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking University National Astronomical Observatories Chinese Academy of Sciences Xinjiang Astronomical Observatory Chinese Academy of Sciences

The very small braking index of PSR J1734-3333, n = 0.9 ± 0.2, chal- lenges the current theories of braking mechanisms in pulsars. We present a possible interpretation that this pulsar is surrounded by a fall-hack disk and braked by it. A modified braking torque is proposed based on the competition between the magnetic energy density of the pulsar and the kinetic energy density of the fall-back disk. With this torque, a self-similar disk can fit all the observed parameters of PSR J1734-3333 with natural initial values of parameters. In this regime, the star will evolve to the re- gion having anomalous X-ray pulsars and soft gamma repeaters in the P -/5 diagram in about 20 000 years and stay there for a very long time. The mass of the disk around PSR J1734-3333 in our model is about 10M similar to the observed mass of the disk around AXP 4U 0142＋61.

关键词： pulsars: individual (PSR J1734-3333) - stars: evolution - stars: neutron

Pulsars in FIRST Observations

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Chinese Journal of Astronomy and Astrophysics 2002年第2期2卷 146-150页

作者： Xiang-Hua Li and jin-lin han National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

We identify 16 pulsars from the Survey of Faint Images of the Radio Sky at Twenty-cm (FIRST) at 1.4 GHz. Their positions and total flux densities are extracted from the FIRST catalog. By comparing the source positions with those in the PSR catalog, we obtain better determined positions of PSR J1022+1001, J1518+4904, J1652+2651, and proper motion upper limits of PSR J0751+1807, J1012+5307, and J1640+2224. The proper motions of the other ten pulsars are consistent with the catalog values.

关键词： pulsar: general -stars: neutron

Discovery of Three Large HII Regions in the Galactic Plane

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Chinese Journal of Astronomy and Astrophysics 2008年第5期8卷 575-579页

作者： Wei-Bin Shi Xiao-Hui Sun jin-lin han Xu-Yang Gao Li Xiao National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Department of Space Science and Applied Physics Shandong University at Weihai Weihai 264209 China

We discovered three large HⅡ regions： G148.8＋2.3, G149.5＋0.0 and G169.9＋2.0 in the Sino-German A6 cm polarization survey of the Galactic plane. They have been identified based on the flat spectral indexes and the... 详细信息

关键词： radio continuum general - methods observational - HⅡ regions

A digital pulsar backend based on FPGA

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Research in Astronomy and Astrophysics 2017年第1期17卷 97-102页

作者： jin-Tao Luo Lan Chen jin-lin han Ali Esamdin Ya-Jun Wu Zhi-Xuan Li Long-Fei Hao Xiu-Zhong Zhang National Time Service CenterChinese Academy of SciencesXi'an 710600China Key Laboratory of Time and Frequency Primary Standards Chinese Academy of SciencesXi'an 710600China National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China Shanghai Institute of Technology Shanghai 200235China Yunnan Observatories Chinese Academy of SciencesKunming 650011China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China

A digital pulsar backend based on a Field Programmable Gate Array （FPGA） is developed. It is designed for incoherent de-dispersion of pulsar observations and has a maximum bandwidth of 512MHz. The channel bandwidth is fixed to 1 MHz, and the highest time resolution is 10 p.s. Testing observations were carried out using the Urumqi 25-m telescope administered by Xinjiang Astronomical Observatory and the Kunming 40-m telescope administered by Yunnan Observatories, targeting PSR J0332＋5434 in the L band and PSR J0437-4715 in the S band, respectively. The successful observation of PSR J0437-4715 demonstrates its ability to observe millisecond pulsars.

关键词： instrumentation miscellaneous - methods data analysis - pulsars general