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速度分布和银盘厚度效应对正常脉冲星Z向分布的影响

The Influence of Velocity Distribution and Thickness Effect of Galactic Disk on the z-Distribution of Normal Pulsars

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【作者】 巍英春彭秋和吴鑫基张明王娜邹志刚艾力·伊沙木丁

【Author】 WEI Ying-chun~1 PENG Qiu-he~2 WU Xin-ji~(3,1) ZHANG Ming~2 WANG Na~1 ZHOU Zhi-gang~4 A.Esamdin~1 1 National Astronomical Observatories,Urumqi Observatory,Chinese Academy of Sciences,Urumqi 830011 2 Department of Astronomy,Nanjing University,Nanjing 210093 3 Department of Astronomy,Peking University,Beijing 100871 4 National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100012

【机构】 中国科学院国家天文台乌鲁木齐天文观测站南京大学天文系北京大学天文系中国科学院国家天文台中国科学院国家天文台乌鲁木齐天文观测站 乌鲁木齐830011南京210093北京100871中国科学院国家天文台乌鲁木齐天文观测站乌鲁木齐830011乌鲁木齐830011北京100012

【摘要】 基于彭秋和等1978年得到的无扰动有限厚盘引力势,根据两个引力势参数(hz1= 0.001kpc,hz2=0.325 kpc)和两个速度分布参数(σv1=115km/s,σv2=200 km/s)组合的4种情况,对4×105颗脉冲星做了三维蒙特卡洛模拟.4×105颗脉冲星按着108年间隔被分成20组,计算了每组“逃逸”脉冲星所占比例.对每组中“未逃逸”脉冲星,分别在0<r<25kpc和5<r<11kpc两个区域中对|z|分布做了统计,研究了“未逃逸”脉冲星在这两个区域中的分段标高和累积标高的演化特征.“未逃逸”脉冲星的分段标高在一定空间范围内的变化不规则,但累积标高的变化却比较平滑.在相对长的时间里(>108年),银盘厚度对脉冲星累积标高演化有显著的复杂影响;在相对短的时间中(<2×107年),这种效应很小,而且累积标高对时间的依赖关系是线性的.在长时间里,初始速度分布对累积标高也有显著影响.在引力势hz2=0.325 kpc的条件下,在径向范围5<r<11kpc和时间t=9.22×106年以及σv2=200km/s的情况下,模拟的累积标高是0.596±0.005 kpc.

【Abstract】 3-D Monte Carlo simulations of 4×105 pulsars based on the undisturbed finitely thick disk gravitational potential derived by Peng et al.(1978) are made in this pa- per under four combinations of the two gravitational potential parameters (hz1=0.001 kpc, hz2=0.325kpc) and two initial velocity distribution parameters (σv1=115 km/s,σv2= 200km/s).The 4×105 pulsars were divided into 20 groups with 100Myr interval and the fraction of“escaped”pulsars of each group is calculated.The“not escaped”pulsars of each group whose simulated projective places on to the Galactic plane lie in the range 0<r<25 kpc and 5<r<11 kpc from the Galactic center respectively are selected to make statistics on absolute height |z| distribution to derive the segmental scale height and the cumulative scale height.The segmental scale heights of“escaped”pulsars change irregularly in some spatial range,while the cumulative scale heights change very smoothly. The effect of the galactic disk thickness has obviously complex influence on the evolution of pulsars’ scale height in the long run (>108yr);but in relatively short time<2×107yr, the effect is very small,moreover,the time dependence of the cumulative scale height is linear.In long period the initial distribution of velocity also has obvious influence on the cumulative scale heights.In the situation of hz2=0.325 kpc andσv2=200 km/s the cu- mulative scale height is 0.596±0.005 kpc in the range 5<r<11 kpc at time t=9.22×106 yr.

【关键词】 脉冲星普遍,恒星演化,银河系结构,银河系
【Key words】 pulsargeneralstarsevolutionGalaxystructuredisk
【基金】 国家自然科学基金(No.10173020和No.10573026)资助
  • 【文献出处】 天文学报 ,Acta Astronomica Sinica , 编辑部邮箱 ,2006年04期
  • 【分类号】P145.6
  • 【下载频次】65
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