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

作　　者：巍英春[1] 彭秋和[2] 吴鑫基[3] 张明[2] 王娜[1] 邹志刚[4] 艾力.伊沙木丁 

机构地区：[1]中国科学院国家天文台乌鲁木齐天文观测站,乌鲁木齐830011 [2]南京大学天文系,南京210093 [3]北京大学天文系,北京100871 [4]中国科学院国家天文台,北京100012

出　　处：《天文学报》2006年第4期362-370,共9页Acta Astronomica Sinica

基　　金：国家自然科学基金(No.10173020和No.10573026)资助

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=0．325kpc）和两个速度分布参数（σv1=115km／s，σv2=200km／s）组合的4种情况，对4×10^5颗脉冲星做了三维蒙特卡洛模拟．4×10^5颗脉冲星按着10^8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．“未逃逡’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（〉10^8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（〈2×10^7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=0．325kpc的条件下，在径向范围5〈r〈11kpc和时间t=9．22×10^6年以及σv2=200km／s的情况下，模拟的累积标高是0．596±0．005kpc．3-D Monte Carlo simulations of 4× 10^5 pulsars based on the undisturbed finitely thick disk gravitational potential derived by Peng et al. （1978） are made in this - per under four combinations of the two gravitational potential parameters （hz1 = 0.001 kpc, hz2 = 0.325kpc） and two initial velocity distribution parameters （σv1=115km/s, σv2 = 200kin/s）. The 4 × 10^5 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 〈 25kpc and 5 〈 r 〈 11kpc 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 （〉 10^8 yr）; but in relatively short time 〈 2 × 10^7 yr, 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 and σ2 = 200km/s the cumulative scale height is 0.5964- 0.005 kpc in t he range 5 〈 r 〈 11 kpc at time t = 9.22 ×10^6 yr.

关 键 词：脉冲星 普遍 恒星 演化 银河系 结构 银河系 盘 

分 类 号：P156[天文地球—天文学]