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Published on November 15, 2007

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Slide1:  Radio pulsars & Anomalous X-ray pulsars(AXP) Qiao G.J. Astronomy Dept. of Peking Univ. Slide2:  Radio pulsars & Anomalous X-ray pulsars(AXP) 1.Radio pulsar ☆ Basic observational facts & derived parameters ☆ Radiation models for radio emission ☆ Radiation models for Gamma-ray emission 2.Anomalous X-ray pulsar(AXP) ☆ Basic observations & Comparison ☆ Accretion Models of AXP & Test of obs. ☆ Accretion models for radio pulsars Slide3:  Radio pulsars: observational facts ● Basic observational facts ☆ Individual and integrated pulse profiles ☆ Polarization ☆ Mode changing ☆ Drifting sub-pulses ● Basic parameters ☆ P,Pdot,DM: observed ☆ ,B: derived Pulsar radiation :  Pulsar radiation Slide5:  脉冲星的个别脉冲 和平均脉冲 Slide6:  Interstellar Dispersion Ionised gas in the interstellar medium causes lower radio frequencies to arrive at the Earth with a small delay compared to higher frequencies. Given a model for the distribution of ionised gas in the Galaxy, the amount of delay can be used to estimate the distance to the pulsar. P--period DM--dispersion measure Slide7:  “S” shape PA & Obs. Slide8:  Mean pulse shapes and polarisation Lyne & Manchester (1988) P.A. Stokes I Linear Stokes V Slide9:  Drifting subpulses PULSE LONGITUDE Drifting subpulses Taylor et al. (1975) Backer (1973) The strength of the magnetic field:  The strength of the magnetic field Pacini 1968: Ostriker&Gunn1969:  Xu & Qiao, 2001, ApJL, 561,L85 Slide11:  Characteristic age of pulsars  Slide12:  Radio pulsars & Anomalous X-ray pulsars(AXP) 1.Radio pulsar ☆ Basic observational facts & derived parameters ☆ Radiation models for radio emission ☆ Radiation models for Gamma-ray emission 2.Anomalous X-ray pulsar(AXP) ☆ Basic observations & Comparison ☆ Accretion Models of AXP & Test of obs. ☆ Accretion models for radio pulsars Slide13:  Radio pulsars: models for radio emission ☆ The magnetosphere of neutron stars ☆ Inner vacuum gap(RS model) ☆ Space charge limited flow ☆ Inverse Compton Scattering model(ICS model) Slide14:  th=3/2 nkT g=GMNSmnh/r2 h=3kTr2/(2GMNS)1 cm  Pulsars: without atmosphere When: T=106 k m=mp, r=RNS=10 km Slide15:  Magnetospere of pulsars Goldreich & Julian, 1969,ApJ,157,869  Slide16:  The magnetosphere of a NS For Crab Pulsar:  Goldreich & Julian, 1969,ApJ,157,869 Slide17:  Mono-generator For the Earth: For the Sun: For Crab Pulsar: Inner gap:  Inner gap Ruderman & Sutherland ,1975,ApJ Slot gap model:  Slot gap model Arons,J. 1983, ApJ Outer gap:  Outer gap Slide21:  Magnetospere of pulsars Am--mass of ion, Z-charge of ion Outer gap, 1 Space charge limited flow Inner gap Slide22:  Radio pulsars: models for radio emission ☆ The magnetosphere of neutron stars ☆ Inner vacuum gap(RS model) ☆ Space charge limited flow ☆ Inverse Compton Scattering model(ICS model) Slide23:  ● Gamma-ray OBS. Of Radio Pulsars Slide24:  Emission beams in RS model Slide25:  Frequency Dependence of Mean Pulse Profile Phillips & Wolsczcan (1992) Geometry of magnetic pole model Slide26:  Radio pulsars: model for radio emission ☆ The magnetosphere of neutron stars ☆ Inner vacuum gap(RS model) ☆ Space charge limited flow ☆ Mode changing & death line ☆ Inverse Compton Scattering model(ICS model) Slide27:  脉冲星的模式变化 Slide28:  Zhang,Qiao,Lin,Han, 1997, ApJ Mode changing Slide29:  Qiao,Xue,Zhang,Xu,Ye,Wang,2003 Slide30:  ω=2γ2ω0(1-βCosθi) Assumption 2: The low frequency wave can Propagate near the surface Qiao & Lin, 1998,A&A ICS Model: emission beams----Core +cones:  ICS Model: emission beams----Core +cones Qiao , 1992, Slide32:  ICS: shift of emission beams Different emission location→shift of the emission beams Qiao & Lin, 1998,A&A Slide33:  Polarization of integrated pulse in ICS V—circular poln L—Linear poln I—Total Intensity Position angle Xu et al. ApJ.2000 Slide34:  Obs. & ICS : Type IIa ICS Obs. Qiao,Liu,Zhang & Han, 2001,AA Phillips & Wolsczcan (1992) Slide35:  Obs. & ICS: Type Ib Obs. ICS Qiao,Liu,Zhang & Han, 2001 Cramer 1994, AAs Slide36:  Obs. & ICS: Type IIb Obs. Qiao,Liu,Zhang & Han, 2001,A & A Cramer 1994, AAs Slide37:  Accelerators: Inner vacuum gap (Ruderman & Sutherland 1975) requiring high binding energy of charges on stellar surface Drifting sub-pulses Xu,Qiao Zhang, 1999,ApJL,522,L112 Deshpannde & Rankin, 1999,ApJ, 524,1008 Slide38:  Radio pulsars & Anomalous X-ray pulsars(AXP) 1.Radio pulsar ☆ Basic observational facts & derived parameters ☆ Radiation models for radio emission ☆ Radiation models for Gamma-ray emission 2.Anomalous X-ray pulsar(AXP) ☆ Basic observations & Comparison ☆ Accretion Models of AXP & Test of obs. ☆ Accretion models for radio pulsars Pulsar Gaps:  Pulsars are broad-band emitters (gamma-ray, X-ray, optical, radio) Pulsars must be particle accelerators Two preferred acceleration regions: --- Polar cap region --- Outer gap region Pulsar Gaps Slide40:  Muslimov & Harding, 2003 Slot gap model Slide41:  Cheng et al. (1986); Romani (2000) Rotating neutron-star model: magnetospheric gaps Inner (polar cap) gap Outer gaps Regions of particle acceleration! W.B = 0 Slide42:  Dyks & Rudak,2003 Caustic Model Slide43:  The problems of the current models for Gamma-rays ● The problems ☆ Polar cap models:   200 ☆ Outer Gap models: Gamma-ray cut off ? ● Where the problems come from? ☆ Polar cap models: did not taking the null surface into account ☆ Outer Gap models: can not correlated with the inner gap ● The way to resolve these problems Inner vacuum gap + Outer gap model ● What can we get? ☆ To result the difficulties in the models ☆ To get a model for radio + Gamma rays Multiple acceleration model (WA model):  Multiple acceleration model (WA model) Qiao,Lee,Wang,Xu, 2003 Slide45:  Observations & theories of MA model MA model Observations Observations and theories of AXP:  Observations and theories of AXP Basic observations &Comparison : AXP( Anomalous X-ray Pulsars) SGR: Soft Gamma-ray Repeaters X-ray Pulsars, Radio Pulsars; Accretion Models of AXP & Test of obs. Accretion models for radio pulsars Basic observations: AXP:  Basic observations: AXP  spin periods P: 6-- 12 s  Pdot 10-11 s/s Large timing noise  Edot LX  spin down time scales: 103—105 yr  very soft X--ray spectra  lack of bright optical counter parts  SNR Mereghetti, et al. astroph/0205122 Basic observations: SGR:  Basic observations: SGR  super-outbursts  1044reg/s (low-energy gamma-ray and X-ray bursts)  Observations for AXP:  spin periods P: 5-- 8 s  Pdot  10-11 s/s  Large timing noise  Edot  LX  soft X--ray spectra  secular spin down on time scales: 103—105 yr  lack of bright optical counter parts  SNR Mereghetti, et al. astroph/0205122 Observations and theories of AXP:  Observations and theories of AXP Basic observations: AXP( Anomalous X-ray Pulsars) SGR: Soft Gamma-ray Repeaters Comparison: Radio Pulsars; X-ray Pulsars Accretion Models of AXP & Test of obs. Accretion models for radio pulsars High mass X-ray binaries:  High mass X-ray binaries Low mass X-ray binaries:  Low mass X-ray binaries Comparison: Radio Pulsars/X-ray pulsars:  Comparison: Radio Pulsars/X-ray pulsars  Radio Pulsars: 0.0016s-8.5s Pulsars in HMXB: 0.069s--1400s SGR: 5s--8s AXP: 6s---12s Compression between AXP and other objects:  Compression between AXP and other objects CCO & DTN:  CCO & DTN AXP: Lx  Edot :  AXP: Lx  Edot Lx & E_dot :  Lx & E_dot (Guseinov et al. 2002). Radio pulsars, AXP & SGR :  Radio pulsars, AXP & SGR Camilo et al.2000,ApJ Pulsars with High-B:  Pulsars with High-B Camilo et al.2000,ApJ PSR(1814-1744)--AXP(2259+586):  PSR(1814-1744)--AXP(2259+586) Bradio BAXP Observations and theories of AXP:  Observations and theories of AXP Basic observations: AXP( Anomalous X-ray Pulsars) SGR: Soft Gamma-ray Repeaters Comparison: Radio Pulsars; X-ray Pulsars Accretion Models of AXP Test of obs. Accretion models for radio pulsars X-ray Bursts from AXP 1E 1048 :  X-ray Bursts from AXP 1E 1048 Magnetars & Disks:  Magnetars & Disks Evolutionary tracks in the P-Pdot diagram:  Evolutionary tracks in the P-Pdot diagram (1) B12 = 1.8, M0,dot = 5 10^28 g /s (2) B12 = 2.8, M0,dot = 1 10^28 g /s (3) B12 = 5.5, M0,dot = 5 10^27 g /s (4) B12 = 8, M0,dot = 3.2 10^28 g /s (5) B12 = 6, M0,dot = 2 10^27 g /s Eksi & Alpar,astroph/0309029 Period evolution of AXPs:  Period evolution of AXPs (1) B12 = 1.8, M0,dot = 5 10^28 g /s (2) B12 = 2.8, M0,dot = 1 10^28 g /s (3) B12 = 5.5, M0,dot = 5 10^27 g /s (4) B12 = 8, M0,dot = 3.2 10^28 g /s (5) B12 = 6, M0,dot = 2 10^27 g /s Eksi & Alpar,astroph/0309029 Test of observations:  Test of observations NS: different B B: obs. ?(Sanwal et al. 2002; Xu et al.2002) Disk: Observed ? Near-IR obs. & Opt obs. (Hullemant et al.2000,2002) Disk: precession?(Qiao et al,2003) NS or Strange star ? SGR: disk+cloud(Xu et al.2001) CYCLOTRON ABSORPTION LINES:  CYCLOTRON ABSORPTION LINES Bignami et al. 3002,Nature 423,725 CCO & DRQNS:  CCO & DRQNS Line: 0 .7, 1.4 and 2.1 keV(Bignami et al.Nature,2003) electron: Bl=61010G, ; proton: Bl=1.6 1014 G (Sanwal et al. 2002) Bp,dp/dt=3×1012G,(Xu et al.2002) Spectrum line of AXP :  Spectrum line of AXP Line: 8.1 keV(astrph/0302490, 0309402) electron:B= 9 × 1011G proton: B=1.6 1015 G IR Observations of AXP:  IR Observations of AXP IR Observation astroph/0204233(1708) astroph/0209599(1048) Hulleman,et al. ApJ,2001,(2259) Hulleman,et al 2000(0142) Durant et al. astr-ph/0309801(0124;1048) Optical Observations of AXP:  Optical Observations of AXP Opt. Observation Hulleman,et al. Nature,2002,,(2259) Hulleman,et al Nature, 2000(0142) Durant et al. astr-ph/0309801(0124;1048) X-ray Bursts from AXP 1E 1048 :  X-ray Bursts from AXP 1E 1048 Mereghetti et al.astroph/0205122 Accretion models for AXP:  Accretion models for AXP Basic observations: AXP( Anomalous X-ray Pulsars) SGR: Soft Gamma-ray Repeaters Comparison: Radio Pulsars; X-ray Pulsars Accretion Models of AXP Accretion models for radio pulsars Optical pulsations from the AXP 4U0142161:  Optical pulsations from the AXP 4U0142161 Kern & Martin, 2002,Nature,417,527 The pulsed fraction of optical light (27 per cent) is five to ten times greater than that of soft X-rays  Magnetar there are no detailed models predicting the opt. emission from magnetars. Crab, Vela:LX /Lopt < 103-4 similar to 4U0142  Precession observations of radio pulsars :  Precession observations of radio pulsars Crab :astr-ph/0303369(103 yr) Vela: Sedrakian et al. 1999,ApJ. 524,241(104 yr) PSR 1642-03: Shabanova et al. 2001, ApJ. 552,321(3.4 Myr) PSR 1842-11: Stairs et al. Nature,2000,406,484(0.11 Myr) Fallback Disk --> precession? :  Fallback Disk --> precession? Free Precession of a Radio Pulsar :  Free Precession of a Radio Pulsar B1828–11: Systematic timing residuals Periods of 1000, 500 and 250 days Pulse shape and torque correlated Stairs et al. 2000 Free Precession of a Radio Pulsar:  Free Precession of a Radio Pulsar BUT: Free precession is not expected in case of pinned vortices in super-fluid interior! An accretion disk model for periodic timing variations of pulsars (Qiao, Xue,Xu, Wang, Xiao. 2003, A&AL):  An accretion disk model for periodic timing variations of pulsars (Qiao, Xue,Xu, Wang, Xiao. 2003, A&AL) An accretion disk model for periodic timing variations of pulsars (Qiao, Xue,Xu, Wang, Xiao. 2003, A&AL):  The gravitational potential The precession angular velocity The simplification An accretion disk model for periodic timing variations of pulsars (Qiao, Xue,Xu, Wang, Xiao. 2003, A&AL) An accretion disk model for periodic timing variations of pulsars (Qiao, Xue,Xu, Wang, Xiao. 2003, A&AL):  An accretion disk model for periodic timing variations of pulsars (Qiao, Xue,Xu, Wang, Xiao. 2003, A&AL) Are there any other observational facts related to the fullback accretion disk? :  Are there any other observational facts related to the fullback accretion disk? Arrival time residuals for 1E 1048.1 astr-ph/0011368:  Arrival time residuals for 1E 1048.1 astr-ph/0011368 Conclusion and discussion 1. Magnetar or disk: ? same observational fact with different point of view !!! 2.More theoretical works and observations are needed. 3. Our point of view: periods:5—10s , spin down age  SNR age & “free precession” and some other observations are favorable to accretion model :  Conclusion and discussion 1. Magnetar or disk: ? same observational fact with different point of view !!! 2.More theoretical works and observations are needed. 3. Our point of view: periods:5—10s , spin down age  SNR age & “free precession” and some other observations are favorable to accretion model At present no one can present an important evidence to distinguish these two models !!! Can we find a way to present an important evidence to distinguish these two models? :  At present no one can present an important evidence to distinguish these two models !!! Can we find a way to present an important evidence to distinguish these two models? PSR(1847-0130)--AXP(2259+586):  PSR(1847-0130)--AXP(2259+586) A challenge to magnetar model: Bradio > BAXP B1847-0130 > Bmagnetar:  B1847-0130 > Bmagnetar  AXP  Radio pulsar Mcloughlin et al.2003, ApJL Slide89:  Thank you! Slide90:  Thank you!

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