共查询到19条相似文献,搜索用时 140 毫秒
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脉冲星PSR1951+32的X射线脉冲辐射程凌翔,李惕碚,孙学军,马宇蒨,吴枚(中国科学院高能物理研究所,北京100039)主题词:脉冲星-X射线源1987年6月,用频率387MHz的射电观测发现了脉冲星PSR1951+32[1],同年7月,在180... 相似文献
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脉冲星PSR B0329+54的多波段观测 总被引:2,自引:0,他引:2
给出1999年3月12日至6月8日,使用国家天文观测中心乌鲁木齐南山站25m射电望远镜在0.327GHz,1.5GHz,2.3GHz,4.8GHz和8.4GHz频段,对脉冲星PSRB0329+54进行的多波段观测结果,PSRB0329+54的辐射呈幂律谱,并出现频谱转折现象,低频段谱指数为1.59,高频段为2.45,平均谱指数为1.72五个频段上的平均脉冲轮廓的角宽度和二个民分峰值间的角宽度都随频 相似文献
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从ROSAT PSPC观测数据中我国发现了与PSR0355+54相关联的脉冲星X射线喷流存在的证据。这是一个与脉冲星自行方向相反的长度为12′的近似线性的辐射特征。假设喷流具有PSR0355+54相同的距离和星际吸收,而其能谱是谱指数为-0.5的幂律谱,可导出喷流的光度为2.48±0.83×10^24J/S。喷流中的平均磁场约为7.9×10^-9T,典型的电子能量为2.1×10^7MeV。 相似文献
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脉冲宽度的测量方法有几种.最常用的脉冲宽度有Wpp(两峰值点的间距)、W50(最高峰值强度50%处的宽度)和W10(最高峰值强度10%处的宽度).另外,还有测量两个最外成分各自强度50%处的宽度Wc50和各自强度10%处的宽度Wc10.利用16颗双锥峰脉冲星和7颗核锥三峰脉冲星样本在1.4 GHz的脉冲轮廓数据,测量了5种脉冲宽度.利用有磁倾角α和撞击角β数据的脉冲星,导出了对应的辐射束半径ρ,并验证其与脉冲星周期P之间的关系ρ∝P-0.5.通过比较5种脉冲宽度导出的ρ与P关系的好坏,发现最外成分之间的宽度比前面3种宽度更好,其中Wc50宽度得出的相关关系最好.由此认为Wc50是最能反映辐射束宽度的测量值.还讨论了脉冲轮廓的对称性,发现后随的锥辐射成分与先导的锥辐射成分相比,更靠近核心辐射成分,两个锥辐射成分的宽度在统计上基本相同. 相似文献
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苏 《紫金山天文台台刊》1999,18(4):361-366
一个在PSPC定位精度内与M81球状星闭G35的光学位置相重合的X射线源从4个曝光时间大于11,000秒的POSATPSPC定点观测中的探测到,在改正了PSPC指向中心的系统偏差后,它与G35的光学位置相差~10’’.7,大大低于~30’’的PSPC空间分辨率,对这个X射线源所作的ROSAT观测分析表明,它的PSPC形态和X射线辐射性质符合M81球状星团亮源应有的特征。 相似文献
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苏晠 《紫金山天文台台刊》1999,(4)
一个在PSPC 定位精度内与M81 球状星团G35 的光学位置相重合的X 射线源从4 个曝光时间大于11 ,000 秒的ROSATPSPC 定点观测中探测到,在改正了PSPC 指向中心的系统偏差后,它与G35 的光学位置相差~10″.7 ,大大低于~30″的PSPC 空间分辨率。对这个X射线源所作的ROSAT 观测分析表明,它的PSPC 形态和X 射线辐射性质符合M81 球状星团亮源应有的特征。 相似文献
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本文介绍人光仪PSP0 的偏振器设计和实验结果。偏振器设计为旋转半滤片加固定偏振片的系统,但在选用偏振器件方面提出了两种方案。对于低价设计的实验结果表明,偏振器可在430780nm 波长范围内工作,能够实现PSP0 在其最佳工作波长的偏振测量。 相似文献
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在此介绍我们基于ASCA 和ROSAT 等X 射线天文卫星,对3C397 、G327 .11 .1 、G21 .50 .9 和RXJ1713 .73946 等超新星遗迹的物理特性进行的分析,简要地讨论了3C397 的非平衡电离双热分量和双极泡结构以及G327 .11 .1 和G21 .50 .9 中隐匿脉冲星的性质,并提出RXJ1713 .73946 和AD393 客星之间可能的关系。 相似文献
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利用紫金山天文台青海观测站13.7米射电望远镜对源IRAS053910217和IRAS065720742进行了12COJ=1-0观测,获得了气体的相应参数;用IRAS及其他红外观测资料,获得了尘埃热结构;探讨了云中气体的热平衡.对于IRAS053910217中由远红外得出的Td<Tk的情形,考虑了几种可能的加热机制.光电加热对该云可能是比较重要的;激波可能是另一种加热途径. 相似文献
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The central and outer components from the radiation beam of a pulsar are called the core and cone components, respectively. It was found in some early researches that a proportion of 0.7 exists between the widths of core and cone components of pulsars. 33 pulsars with signi?cant core and cone components are selected to verify it. The component separations are made by ?tting the integrated pulse pro?les of these pulsars with Gaussian functions, so as to obtain the widths and errors of all the core and cone components. The relation between the widths of core and cone components is investigated for the triple-peaked and quintuple-peaked pulsars, respectively. We ?nd that there are no signi?cant differences between the widths of core and cone components, the proportion of between the widths of core and cone components that reported by previous studies does not exist. 相似文献
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Peter L. Gonthier Sarah A. Story Brian D. Clow Alice K. Harding 《Astrophysics and Space Science》2007,309(1-4):245-251
We present results of our pulsar population synthesis of normal and millisecond pulsars in the Galactic plane. Over the past
several years, a program has been developed to simulate pulsar birth, evolution and emission using Monte Carlo techniques.
We have added to the program the capability to simulate millisecond pulsars, which are old, recycled pulsars with extremely
short periods. We model the spatial distribution of the simulated pulsars by assuming that they start with a random kick velocity
and then evolve through the Galactic potential. We use a polar cap/slot gap model for γ-ray emission from both millisecond and normal pulsars. From our studies of radio pulsars that have clearly identifiable core
and cone components, in which we fit the polarization sweep as well as the pulse profiles in order to constrain the viewing
geometry, we develop a model describing the ratio of radio core-to-cone peak fluxes. In this model, short period pulsars are
more cone-dominated than in our previous studies. We present the preliminary results of our recent study and the implications
for observing these pulsars with GLAST and AGILE.
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Xiao-Peng You Jin-lin Han National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2006,6(2):237-246
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. 相似文献
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Guo-Jun Qiao Xu-Dong Wang Hong-Guang Wang Ren-Xin XuDepartment of Astronomy CAS-PKU Joint Beijing Astrophysics Center Peking University Beijing 《中国天文和天体物理学报》2002,2(4)
Pulsar radio emission beams have been studied observationally for a long time, and the suggestion is that they consist of the so-called core and conal components. To reproduce these components is a challenge for any emission model, and that the pulse profile of pulsars changes with frequency presents even a greater challenge. Assuming a local surface magnetic structure (to produce the core or central beam) and a global dipole magnetic field (to produce the conal beams), Gil & Krawczyk (1997) applied curvature radiation to the pulse profile simulation of PSR J0437-4715 (hereafter the GK model). Here we present an alternative multi-frequency simulation of the same profiles within the framework of the Inverse Compton Scattering (ICS) model. It is obtained from our simulation (1) that besides the core, the inner cone and the outer cone, there is an outer-outer cone; (2) that the emission components of the core and cones evolve strongly with frequency. Some important differences between the ICS model and the 相似文献
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Alice K. Harding Isabelle A. Grenier Peter L. Gonthier 《Astrophysics and Space Science》2007,309(1-4):221-230
Radio-quiet γ-ray pulsars like Geminga may account for a number of the unidentified EGRET sources in the Galaxy. The number of Geminga-like
pulsars is very sensitive to the geometry of both the γ-ray and radio beams. Recent studies of the shape and polarization of pulse profiles of young radio pulsars have provided
evidence that their radio emission originates in wide cone beams at altitudes that are a significant fraction (1–10%) of their
light cylinder radius. Such wide radio emission beams will be visible at a much larger range of observer angles than the narrow
core components thought to originate at lower altitude. Using 3D geometrical modeling that includes relativistic effects from
pulsar rotation, we study the visibility of such radio cone beams as well as that of the γ-ray beams predicted by slot gap and outer gap models. From the results of this study, one can obtain revised predictions
for the fraction of Geminga-like, radio quiet pulsars present in the γ-ray pulsar population.
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R. N. Manchester 《Journal of Astrophysics and Astronomy》1995,16(2):107-117
Observations of mean or average pulse profiles and their polarization give us much information on the shape of pulsar beams.
The observed polarization variations, profile symmetry and frequency dependence of profile shape strongly suggest that the
emission beam is conical and emitted from the vicinity of a magnetic pole. Central and outer parts of the beam have somewhat
different properties, but the evidence is that they are emitted by the same basic mechanism. Recent observations suggest that
the highly polarized pulse components seen in young pulsars may be emitted at a large angle to the magnetic axis. 相似文献
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D. C. Backer 《Journal of Astrophysics and Astronomy》1995,16(2):165-171
Two investigations of millisecond pulsar radiation are discussed: average total intensity pulse morphology and individual
pulse to pulse fluctuations. The average emission profiles of millisecond pulsars are compared with those of slower pulsars
in the context of polar cap models. In general the full widths of pulsar emission regions continue to widen inversely with
periodP as P-(0.30-0.5) as expected for dipole polar cap models. Many pulse components are very narrow. The period scaling of pulsar profiles -separations
and widths -can tell us about the angular distribution of radiating currents. An investigation of individual pulses from two
millisecond pulsars at 430 MHz shows erratic pulse to pulse variations similar to that seen in slow pulsars. PSR B1937+21
displays occasional strong pulses that are located in the trailing edge of the average profile with relative flux densities
in the range of 100 to 400. These are similar to the giant pulses seen in the Crab pulsar. 相似文献
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There are a few methods of measuring pulse widths. Among the most often used pulse widths there are Wpp (the distance between two peak value points), W50 (the width at the place of 50% of the highest peak intensity) and W10 (the width at the place of 10% of the highest peak intensity). In addition, there are also the width Wc50 at the place of 50% of their respective intensities and the width Wc10 at the place of 10% of the respective intensities of the two outermost components. The data of the pulse profiles of the sample of 16 double-cone peak pulsars and 7 core-cone triple peak pulsars at 1.4 GHz are utilized to measure 5 kinds of pulse widths. The pulsars with the data of the magnetic inclination α and impact angle β are employed to derive the corresponding radiation beam radius ρ, and the relation between ρ and the pulsar period P, ρ ∝ P?0.5, is verified. Via a comparison between the qualities of the relation between ρ and P derived from the 5 kinds of pulse widths it is found that the width between the outermost components is better than any one of the first 3 kinds of widths, of which the correlative relation obtained from the Wc50 width is the best. From this it is considered that Wc50 is the measured value that can fully reflect the emission beam width. The symmetry of the pulse profile is also discussed and it is found that from the comparison with the preceding cone emission component the following cone emission component is much closer to the core emission component, and the widths of the two cone emission components are basically the same according to statistics. 相似文献
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R. K. Manchanda 《Astrophysics and Space Science》1989,161(1):85-98
We suggest that the variable pulse profile of GX 1+4 in the low-energy X-ray region results from the superposition of polar and disk components. The anomalous appearance during the spin-down episode can then be explained, if we consider a transition from thin to thick accretion disk configuration which can develop at midly super-Eddington luminosity levels of the source. a close examination of the data suggests that the intrinsic period of the pulsar is 4 min. A switching disk geometry can provide a natural explanation to pulse profile variations in more luminous accreting binary pulsars and also account for the transition between high and low spectral states seen in the case of the Cyg X-1 and low-mass X-ray binary systems. 相似文献