毫秒脈沖星的偏振觀測(cè)課件

1、偏振電矢量振動(dòng)方向?qū)τ趥鞑シ较虻牟粚?duì)稱(chēng)性叫做偏振，它是橫波區(qū)別于其他縱波的一個(gè)最明顯的標(biāo)志。偏振光的描述方法經(jīng)典方法斯托克斯參數(shù)法 I：總強(qiáng)度 (Q2+U2)1/2: 線(xiàn)偏振成分的強(qiáng)度 V：圓偏振成分的強(qiáng)度 tan-1(U/Q)/2:線(xiàn)偏振位置角斯托克斯參數(shù)的性質(zhì)自然光：I，0，0，0強(qiáng)度為I的自然光可看作是兩束強(qiáng)度相等、不相干的反向偏振光I/2,Q,U,V和I/2,-Q,-U,-V的混合。任意偏振光I,Q,U,V可以分為一束自然光I-(Q2+U2+V2)1/2,0,0,0和一束完全橢圓偏振光(Q2+U2+V2)1/2,Q,U,V, 或者一束自然光I-(Q2+U2+V2)1/2-|V|,0,0

2、,0和一束完全線(xiàn)偏振光(Q2+U2+V2)1/2,Q,U,0以及一束完全圓偏振光|V|,0,0,V。Polarization measurementsRadio telescopes usually take measurements in two orthogonal polarizations.For a dual-linear feed For a dual-circular feed 法拉第旋轉(zhuǎn)效應(yīng)=RM2脈沖星的周期分布Millisecond pulsarsNormal pulsarsP-Pdot diagram Harding 2013Duty cycle (W/P) Kramer

3、 et al. 1998光速圓柱半徑Pulsar emission beamGil et al . 1984Opening angle Kramer et al. 1998InterpulseThe secondary pulses separated by about 180from the main pulse.The main pulse and interpulse originate from oppsite magnetic poles.While only about 2% of all normal pulsars are known to exhibit interpulse

4、s or pre- or postcursors, about 36% of all Galactic MSPs known either emit a post or precursor or exhibit an interpulse. Kramer et al. 1998Rotating Vector Model （Radhakrishnan & Cooke 1969） Von Hoensbroech & Xilouris 1997Polarization similarity Han et al. 2009 Ord et al. 2004Parkes Pulsar Timing Arr

5、ay projectPPTA脈沖星的偏振輪廓Yan et al. 2011aPA variations with timeLong-term changes in pulsar PAs can result from changes in the polarization of the emitted radiation or from changes in the RM along the path. PA=RM2Intrinsic PA changes could result from precession of the pulsar spin axis or changes in th

6、e magnetic configuration of the star. RM changes can occur as the path to the pulsar traverses different regions of the interstellar medium (ISM) or in certain changes the Earths ionosphere.Vela pulsar (PSR B0833-45)discovered in 1968, 89msnear the center of the Vela nebulaHamilton et al .1985 雙脈沖星系統(tǒng) J0737-3039discovered in 2003,22.7ms, 2.77sa laboratory for strong-field gravity and plasma physics Yuen et al. 2012PA variations for PPTA pulsars Yan et al. 2011b總結(jié)毫秒脈沖星的偏振性質(zhì)和普通脈沖星是相似的，說(shuō)明兩類(lèi)脈沖星基本的輻射機(jī)制是相同的然而毫秒脈沖星的偏振位置角和輪廓形狀比普通脈沖星復(fù)雜，說(shuō)明毫秒脈沖星的輻射區(qū)結(jié)構(gòu)更復(fù)雜經(jīng)過(guò)電離層修正以后，