脉冲星观测技术与搜寻ppt课件

脉冲星观测技术与搜寻,1,脉冲星观测技术和搜寻,脉冲星观测技术与搜寻,2,思考题/提纲,脉冲星信号发射时的特征是什么？脉冲星信号传播过程中有那些改变？脉冲星观测可以用什么样的望远镜？脉冲星观测和搜寻的关键技术点是什么？脉冲星搜寻中选择效应过去脉冲星发现和搜寻结果脉冲双星系统的搜寻特殊目标的脉冲星搜寻将来脉冲星搜寻的主要任务,脉冲星观测技术与搜寻,3,MilkyWayinSky,0329,中子星半径仅10公里，有极强的磁场108-14G，极高的密度1014g/cm3.它们旋转，产生脉冲，成为脉冲星！,脉冲星观测技术与搜寻,4,超新星爆炸后留下：超新星遗迹，和中子星或黑洞！,中子星半径仅10公里，有极强的磁场108-14G，极高的密度1014g/cm3.它们旋转，产生脉冲，成为脉冲星！,脉冲星观测技术与搜寻,5,电磁波谱,光学波长：几千埃(10-10m)电波：=1m=300MHz=1mm=300GHz,脉冲星观测技术与搜寻,6,1054AD爆炸，中国史书记录完整，年龄可靠.脉冲星周期33毫秒.该脉冲星从射电到光学到高能，全波段辐射,蟹状星云及其脉冲星,(Abdoetal.2010),脉冲星观测技术与搜寻,7,银河系=恒星+星际介质,+中子星+黑洞+暗物质,Crab从射电到光学到X和，全波段辐射！,讨论几个问题：1.不同波段周期及变化是否相同？2.不同波段的脉冲相位一样？3.不同波段的脉冲现状是否相同？4.那些波段受星际介质影响？,脉冲星观测技术与搜寻,8,波形随频率变化:辐射频率与辐射高度有关,Thorsett1991Phillips但群速度为,考虑电磁波在稀薄气体中传播时，电子被电磁波电场加速运动的方程为,n个电子一起引起的偶极偏振电场：,介电常数为,共振频率为=0,介质对电磁波的反射系数为,电磁波的传播延时为,注意：与光速的差取决于2仅仅低频电磁波收星际介质影响！,脉冲星观测技术与搜寻,10,方法：将频段分为多个小频带探测每个小频带的脉冲，然后相加。,射电波段观测：色散要消除！,脉冲星观测技术与搜寻,11,地球大气窗口,射电窗口,大气吸收率,脉冲星观测技术与搜寻,12,Interstellarmedium:CloudsBW=300MHz;1024ChannelIntegrationtime:67s(precursor),135s/278s(ongoing)2.5to5timesfurtherthanParkesMBBeamsize:204”x232”;outerbeam:329”x384”Centralbeamgain:11K/Jy;outerbeamgain:8K/JyTsys:about25Kat1400MHzDeepGalacticplanesurvey:|b|5deg,32l80degMediumlatitudesurveys:50.18Msun0.009Msun(10MJup)0.19Msund6.7kpc2.2kpc2.5kpc3.9kpc,DAmicoetal.(2001),脉冲星观测技术与搜寻,99,脉冲星观测技术与搜寻,100,ProperMotions1stgasdetectioninGC,UsingParkestelescope33MSPsdetectedRecentdiscoveriesusingaccelerationsearchMostinbinarysystemsShortestorbitofanyradiopulsar,i.e.96minAccuratepositions,47Tucanae,球状星团的脉冲星搜寻,11MSPsdiscovered1991-1995.Allbuttwosingle(non-binary)12morePSRsdiscoveredusingmultibeamreceiver.Allbuttwobinary.,脉冲星观测技术与搜寻,101,PSRB,PSRD,PSRE,PSRC,PSRA,NGC6752:Twopulsarsatunusualpositionsandmovingveryfast!,脉冲星在星团中高速运动：探测到星团中心的黑洞？.No！,脉冲星观测技术与搜寻,102,Terzan5:Massivecluster8.52kpc(l,b)=(3.8,1.7)：33pulsars,mostlyMSPsRansometal.2005,Science,307,892PSRJ1748-2446adfastestspin(716Hz)Hesselsetal.2006，Nature,Gain(i.e.area)：3timeslargerthanParkes“Clean”600MHzbandatlowS-band(1950Mhz)ReducesDM-smearing(-3)N-star1.7MPSRJ1748-2446ad-fastestknownpulsar!P=1.3959ms,f0=716.3Hz,S200080Jycircularorbit,Pb=1.09d，mc0.14MEclipsedfor40%oforbit,球状星团的脉冲星搜寻,脉冲星观测技术与搜寻,103,27newMSPsinTerzan5=30intotal!Ransometal.,2005,Science,307,892,脉冲星观测技术与搜寻,104,脉冲星观测技术与搜寻,105,脉冲星观测技术与搜寻,106,脉冲星观测技术与搜寻,107,FastestMillisecondPulsars:Aremanyofthefastest-spinningpulsarshidden?,5ofthe10fastest-spinningpulsarsshoweclipses.5ofthe10fastest-spinningpulsarsarefoundinTerzan5,Arethefrequencieslimitedbygravitationalradiation?,脉冲星观测技术与搜寻,108,327MHzVLAimage,DetectingpulsarsinSgrA*isdifficultbecauseoftheintensescatteringscreeninfrontofSgrA*.Multipathdifferentialarrivaltimesd2000-4secSolution:highsensitivityathighfrequency,SgrA*=3106BHwithasurroundingstarclusterwith108stars.Manyoftheseareneutronstars.,银河系中心的脉冲星搜寻：到目前为止，均以失败告终！Why？,脉冲星观测技术与搜寻,109,SamplingofpulsarL-Pdistributionwithdifferentinstruments,detectable,EVLAcansampleagoodfractionoftheluminosityfunctionAsouthern-hemisphereArecibo-likeaperturesamplesevenmoreSKAmaybenecessarytorealizetimingprecisionrequiredforphysicspayoff(blackholespin,GRtests),银河系中心附近的脉冲星搜寻,脉冲星观测技术与搜寻,110,超新星遗迹：深“曝光”,在SNRG0.9+0.1中发现J17472809：DM=1133,P=52ms,S=40uJy;Edot=4.3*1037ergs;t=5.3kyr!Dist=813kpc！只有用GBTat2GHz测到！Parkes1.4GHz：Scattering=55ms！,(Camiloetal.2009,ApJ700,L23),脉冲星观测技术与搜寻,111,Magnetar：RadioPulsar！,Neutronstarswithperiodsbetween5-12secPeriodderivatives10-1010-13s/smagneticfieldoftheorderof1015G!Radio-quietbutburstingX-ray/gamma-raysourcesPoweredbyenergystoredinmagneticfield,XTEJ1810-197:Aradioemittingmagnetar(Camiloetal.2006):,-IdentifiedasAXPduringoutburst2003P=5.54s,dP/dt=10-11,B2.4x1014G;T7600yrFirstasradiosourceinVLAcontinuumPulsedemissionbyParkesVerystrong,flatspectrumsourceComplicated,changingprofile:Mainandinterpulsecomponent,脉冲星观测技术与搜寻,112,XTEJ1810-197:Aradioemittingmagnetar,Propolarizationarechangingwithtime,Krameretal.(2007),脉冲星观测技术与搜寻,113,脉冲星发现的数目与年代,脉冲星观测技术与搜寻,114,SKApulsarsurvey:(600sperbeam)104PSR,MillisecondPulsars,RelativisticBinaries,Today,Today,Future,SKA,SKA,Future,only6!,脉冲星观测技术与搜寻,115,FAST：最重要的研究课题：脉冲星宇宙中氢原子与恒星星系的形成其他（如：寻找地外文明！）,球反射面：口径500m球冠张角：110120有效照明口径：300m天空覆盖：天顶角40工作频率：70MHz3GHz灵敏度：2000/K多波束：19跟踪精度：8,脉冲星观测技术与搜寻,116,FAST:skycoverageandpulsarsurvey,脉冲星观测技术与搜寻,117,Whymorepulsars?,ExtremePulsars:P5secPorb1013G(magnetars?)V1000kms-1,Newinstruments(AO,GBT,FAST,SKA)candramaticallyincreasethevolumesearched(galactic&extragalactic),Testsoftheoriesofgravity:NS-NS&NS-BHMoreMSPforGravitationalwavedetectorsMoreextremePSRsforExtremematterphysicsRelativisticplasmaphysicsMagnetospheres+RadiationmechanismsProbesofturbulentandmagnetizedISM(&IGM)Endsta