脉冲星的高辐射能优秀PPT.ppt

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1、1 1、脉冲星的基本特性、脉冲星的基本特性2 2、脉冲星的观测结果、脉冲星的观测结果3 3、描述脉冲星高能、描述脉冲星高能辐射的模型射的模型 外外间隙模型隙模型内容内容1 1）中子星观念的提出中子星观念的提出1 1、脉冲星的基本特性、脉冲星的基本特性Baade&Zwicky(1934)提出宇宙中存在中子星 Oppenheimer&Volkoff(1939)估计了中子星的第一个态方程：质量 1.4 太阳质量；半径 10 公里；密度1014 g cm-3 .Pacini(1967)Pacini(1967)提出来自提出来自转动的中子星的的中子星的电磁磁辐射可以射可以驱动CrabCrab星云星云 Pu

2、lses from the Vela Pulsar2 2）脉冲星的发觉）脉冲星的发觉19671967年，年，Jocelyn BellJocelyn Bell每天每天早上在射早上在射电望望远镜中都中都观测到短的、到短的、规则的、象的、象时钟一一样的的辐射射脉冲。脉冲。Hewish Hewish 等人等人(Hewish et al.1968,Nature)(Hewish et al.1968,Nature)发觉发觉了了一一颗颗射射电电放射的快速脉冲源放射的快速脉冲源PSR B1919+21.PSR B1919+21.Gold(1968,Nature)Gold(1968,Nature)指出脉冲星就是

3、表面磁指出脉冲星就是表面磁场1012G1012G的的中子星。中子星。3 3）脉冲星的分类）脉冲星的分类 孤立中子星：孤立中子星：通通过过快速自快速自转变转变慢慢辐辐射能量射能量（一般（一般 0)0)。脉冲脉冲X X射射线线源：源：双星系双星系统统中的致密天体中的致密天体（一般（一般为为中子星）；从正常伴星中吸中子星）；从正常伴星中吸积积物物质质(P10s secs,dP/dt0)dP/dt0)。已已观测观测到大部分脉冲星自到大部分脉冲星自转变转变慢，即慢，即dP/dt0dP/dt0。所以它。所以它们损们损失失转动转动能可以能可以说说明明观观测吗测吗？转动转动磁偶极子的能磁偶极子的能损损：磁磁场

4、场与周期和周期倒数的关系：与周期和周期倒数的关系：脉冲星年脉冲星年龄龄的估算：的估算：Pulsar pictureLight cylinderOpenmagnetosphereRadio beamr=c/w wBClosed magnetosphereNeutron starmass=1.4 solar massesradius=10 kmB=10 to 10 Tesla49Pulsar model2 2、脉冲星的、脉冲星的观测结果果1）射电波段：2000 2000 2000 2000 颗脉冲星颗脉冲星颗脉冲星颗脉冲星 2）X射线波段：51颗X射线脉冲星彩色的符号表示探彩色的符号表示探测到到X

5、 X射射线脉冲脉冲转动驱动的脉冲星分布的脉冲星分布28颗正常脉冲星 23颗毫秒脉冲星3 3）高能伽）高能伽玛射射线：History:SAS 2,COSB(1970s-1980s).EGRET(1990s)Coming satellite:GLAST（1）EGRET观测成果Increased number of IDs sources by large factors发觉了170颗未证认的伽玛射线源（2 2）观测到的伽到的伽玛射射线脉冲星脉冲星 Crab脉冲星 Vela脉冲星 PSR B150958 PSR B104658 PSR B170644 PSR B195132 PSR B105552

6、Geminga脉冲星Pulses at multi-wavebandsEnergy spectra of gamma-ray pulsars3 3、描述脉冲星高能、描述脉冲星高能辐射的模型射的模型目前有两类公认的模型：目前有两类公认的模型：（1 1）内间隙模型内间隙模型 (Harding et al.1978,ApJ 225,226;Daugherty&Harding 1982 ApJ 252,337;1996 ApJ 458,278;Zhang&Harding,2000,ApJ;Sterner et al.1995,ApJ 445,736).（2 2）外间隙模型）外间隙模型 (Cheng,H

7、o,Ruderman,1986,ApJ 300,500;300,522;Chiang&Romani 1994,ApJ 436,754;Romani,1996,ApJ 470,469,Zhang&Cheng 1997,ApJ 487 370;Hirotani&Shibata 2001,MNRAS 325,1228)Schematic geometry of polar and outer gaps.Dark solid regions are thin gaps of younger pulsars.Hatched regions are thick gaps of older pulsars（

8、1 1）我们的外间隙模型我们的外间隙模型我们的外间隙模型我们的外间隙模型正负电子由外间隙中正负电子由外间隙中 E E|加速加速相对论性相对论性 e e+/e/e-通过同步曲率辐射通过同步曲率辐射和和ICIC过程产生高能伽玛射线过程产生高能伽玛射线来自表面的软来自表面的软X X射线由回流电流与射线由回流电流与NSNS表面碰撞产生。在外间隙中高表面碰撞产生。在外间隙中高能伽玛射线与这些软能伽玛射线与这些软X X射线碰撞产射线碰撞产生正负电子对，从而维持外间隙生正负电子对，从而维持外间隙存在。存在。我我我我们们的厚的厚的厚的厚间间隙模型隙模型隙模型隙模型（Zhang&Cheng,1997,ApJZh

9、ang&Cheng,1997,ApJZhang&Cheng,1997,ApJZhang&Cheng,1997,ApJ）Outer gap size：Luminosity：Spectrum 特点特点：(1)(1)自洽性自洽性自洽性自洽性;(2)(2)普普普普适适适适性性性性。对对一一一一给给定定定定的的的的脉脉脉脉冲冲冲冲星星星星（即即即即周周周周期期期期P P和和和和表表表表面面面面磁磁磁磁场场B B已已已已知知知知），可可可可估估估估计计伽伽伽伽玛玛射射射射线线光光光光度度度度和能和能和能和能谱谱。依次模型，我们开展了系列的工作依次模型，我们开展了系列的工作1)Conversion effi

10、ciency of gamma-ray pulsars.2)The statistics of gamma-ray pulsars.3)Radiation features of X-ray pulsars.4)The statistics of X-ray pulsars.5)The contribution of gamma-rays from pulsars to Galactic gamma-rays.6)The contribution of positrons from pulsars to Galactic positrons.7)Unidentified gamma-ray s

11、ources and gamma-ray pulsars.2)Three-Dimensional Model3D magentic structure,the phase profile and phase-resolved spectra.Application to Crab pulsar.Phase-resolved high-energy features of Crab-like pulsars.Phase-resolved high-energy features of Geminga pulsar.3)Crab X-ray pulses,HE Emission of AXPs a

12、nd SGRsZhang,L.&Cheng,K.S.2002,ApJ,569,872Cheng&Zhang,2001,ApJ,562,918Zhang,&Cheng,2002,ApJ,579,7163)MS Pulsars HE Emission弱磁场，短周期Zhang&Cheng,K.S.2003,A&A,398,6394)New version of outer gapmagnetosphere geometry inclination effectObservation indicates(Thompson et al.2001):L L sd.ZC97 model predicts L

13、 (B/P)0.3,e.g,the ratio of(B/P)0.3 for PSR B1055-52 to that for Geminga is 0.9.But,the observed ratio 8(Kaspi et al.2000).Outer gap:Outer gap:f0(P,B)=5.5 P 26/21 B-4/712Gamma-ray LuminosityRadio-loud:L L 0.30 sd Radio-quiet:L L 0.38 sd Solid line:lg L 20.42+0.38lg LsdDashed line:lg L 3.25+0.30lg Lsd

14、Death lines of the pulsars with self-sustained outer gaps.(1)Crab-like(2)Vela-likeChen&Ruderman 1993(3)ZC97 model(4)uniform(5)cosineNew modelDeath lines Zhang,L.et al.2004,ApJ,604,317Cheng,K.S.,Zhang et al.2004,ApJ,608,418Pulsed X-ray luminosity of normal X-ray pulsarsX-ray LuminosityZhang&Jiang,200

15、5,A&AGamma-ray statistical propertiesZhang,Han,Jiang,2005,A&A,429,489HE properties of High-field PulsarsZhang,Jiang,2005,ApJ,631High-filed:1013-1014 G 28 high-pulsar pulsars感感谢！脉冲星高能脉冲星高能辐射平均射平均谱 Zhang&Cheng,1997,ApJ,487,370Cheng&Zhang,1998,ApJ,498,327脉冲星辐射的转换效率脉冲星辐射的转换效率 Return Zhang&Cheng,1998,MNR

16、AS,294,177Solid boxes:OursEmpty triangles:Harding,1981Empty diamonds:Dermer&Sturner 1994 X-X-射线脉冲星的辐射特性射线脉冲星的辐射特性 Return Cheng,Gil&Zhang,1998,ApJ,493,L35Cheng&Zhang 1999,ApJ,515,337 X-X-射线脉冲星的统计性质射线脉冲星的统计性质 Return Zhang&Cheng 1999,ApJ,526,327 射线射线脉冲星的统计特性脉冲星的统计特性 Return Cheng&Zhang 1998,ApJ,498,327

17、射线脉冲星产生的射线脉冲星产生的 射线对银河射线对银河 射线的贡献射线的贡献 Zhang&Cheng,1998,MNRAS,294,327ReturnCosmic positrons Return Comparison of observed e+/(e-+e+)ratio with predicted ones.The short-dashed curve is the ratio of positron background and total electron background given by Moskalenko&Strong(1998).The solid,long dashe

18、d and dot-dashed curves are the ratios including the contribution of the mature gamma-ray pulsars with birth rates of one per 100 yrs,one per 50 yrs and one per 30 yrs respectively.(Zhang&Cheng,2001,A&A)未证认的未证认的 射线源与射线源与 射线脉冲星的关系射线脉冲星的关系 Solid lines:gamma-ray selection effectDashed lines:radio&gamma

19、-ray selection effectsZhang&Cheng,1998,A&A,335,234Zhang,Zhang&Cheng,2000,357,957 Geminga Return Phase-resolved and phase-averaged gamma-ray spectra of the Geminga pulsarEmission projection and pulseprofile for Geminga parameter.Panel A:Photon emission from thepulsar as a function of phase.Panel B:Pu

20、lse profile.Crab 3D structure of the outer gapsThe spectra of CrabZhang,Cheng,K.S.Mei,D.C.2000,CPL,17,544Cheng,K.S.Ruderman,M.Zhang,L.2000,ApJ,537,964 PSR B1509-58PSR B1509-58 Emission projection onto the(,)plane and pulse profile.Panel A:photon emission;Panel B:radial distance vs.;Panel C:pulse profile.The spectrum of PSR B1509-58Zhang&Cheng 2000,A&A,363,575