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Qiao,G.J. Dept. of Astronomy, Peking Univ. Collaborators: Zhang, B.( University of Nevada ), Xu, R.X.(PKU), Han,J.L.(NAOC), Lin,W.P.(SHO),Lee,K.J.(PKU) Xia,X.Y. Radio and Gamma-ray emission of pulsars
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I. Radio emission (Inverse Compton scattering model: ICS ) II. Inner annular gap & gamma-ray emission Radio + Gamma ray emission III. Pulsar: Neuron stars or Strange stars?
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Core beam Beam-frequency Mode changing Bi-driftingGamma-ray Core gapAnnular gap Strange stars
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Pulsar emission beams
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Observations
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Emission beams Rankin, 1983, ApJ,274,333
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Theories
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Ruderman & Sutherland (RS) Model Ruderman & Shutherland,1975, ApJ,196,51
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Emission beams in RS model Ruderman & Sutherland, 1975 Emission beams Hollow cone only!
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Obs. & Theory(ICS) (1) Core + Cones (2) Different components come from different locations (3) Pulse profile shapes changing with freq. (4) Mode changing (5) Bi-drifting Pulsars: NS or Strange stars?
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ICS Model: emission beams ⇒ Core +cones Qiao, 1992
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ICS: shift of emission beams Different emission location→shift of the emission beams Qiao & Lin, 1998, A&A,333,172
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Poln: Beam shift→PA jumps Xu, Qiao & Han, 1997, AA
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Poln: PA jump Xu, Qiao & Han, 1997, AA
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ICS model: inner gap sparking → ω 0 ω=2γ 2 ω 0 (1-βCosθ i ) Qiao & Lin, 1998, A&A
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Core beam Beam-frequency Mode changing Bi-driftingGamma-ray Core gapAnnular gap Strange stars
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RS model Qiao,Liu, Zhang,& Han, 2001,AA Lyne & Manchester (1988) & Sieber et al. (1975),Kramer,(1994)
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“S” shape PA & Obs.
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Poln of integrated pulse in ICS V —circular poln L —Linear poln I —Total Intensity Position angle Xu,Liu,Han,Qiao, 2000, ApJ
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Core beam Beam-frequency Mode changing Bi-driftingGamma-ray Core gapAnnular gap Strange stars
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Mode changing of pulsars Rankin, 1986
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Zhang,Qiao,Lin,Han, 1997 Tree mode of sparking Thermal ICS Curvature radiation Resonant ICS
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Mode change pulsars Zhang,Qiao,Lin,Han, 1997,ApJ Zhang,Qiao, Han, 1997,ApJ
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Core beam Beam-frequency Mode changing Bi-driftingGamma-ray Core gapAnnular gap Strange stars
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☆ Polar cap (polar gap) Basic Observational facts vs Theories ☆ Radio--- Gamma-rays: Obs. Outer gapGamma-rayRadio
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The magnetosphere of a NS +
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Inner annular gap
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Qiao,Lee,Wang,Xu, Han, 2004a,ApJL
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I nner annular gap Qiao,Lee,Wang,Xu, 2004a, ApJL
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Inner Annular Gap Qiao,Lee,Wang,Xu, 2004a, ApJL
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Core beam Beam-frequency Mode changing Bi-driftingGamma-ray Core gapAnnular gap Strange stars
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Mclaughlin 2003,astr-ph/0310454 Bi-drifting: Obs.
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Drifting subpulses PULSE LONGITUDE Drifting subpulses Taylor et al. (1975) Backer (1973)
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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
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Inner Annular Gap : V= c E x B / B^2
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Bi-drifting: fitting Mclaughlin 2003,astr-ph/0310454 Qiao,Lee,Zhang,Xu,Wang,2004b, ApJL
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Neutron stars: Binding energy ≤ 10 KeV no gap can be formed!!! Binding energy > 10 KeV only one gap cab be formed: core or annular gap Strange stars: both core & annular gap can be Formed !
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● Annular Gap mole: different Gamma-ray pulsars can be fitted ● Pulsars: Strange stars? ● Observational check: Polarization at high energy bands ● Theory: two caps=two gap? Conclusion and discussion
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Core beam Beam-frequency Mode changing Bi-driftingGamma-ray Core flowAnnular flow Neutron stars ? ? ? Qiao,Lee,Zhang, Wang & Xu,,2005,
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Can free flow produce drifting pulses? If not, can we distinguish NS from SS? ♣ More drifting phenomena need to be obs. ♣ Sub-millisecond pulsar need to be found? 100 m telescope will be helpful for the research above!
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? 100m at Effelsberg New Green Bank Telescope Jodrell Bank KaShi,China ?
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Thank you !
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Multi-cones in the ICS model Qiao,Wang,Wang,Xu, 2002,ChJAA
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Multi-frequency fitting of PSR J0437-4715 Qiao,Wang,Wang,Xu, 2002,ChJAA
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Magnetosphere of pulsars Goldreich & Julian (1969)
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Charge density — ρ GJ (Goldreich & Julian 1969 ) Acceleration electric field Acceleration electric field
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I nner annular gap Qiao,Lee,Wang,Xu, Han, 2004
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Ruderman & Sutherland, 1975 Neutron stars: binding energy > 10KeV Can’t form core and annular gap at the same time!
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Strange stars: binding energy << 10KeV Can form core and annular gap at the same time!
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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
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Crab pulsar
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Vela Pulsar
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Geminga
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Inner annular gap Qiao,Lee,Wang,Xu, 2003
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PA jumps: individual pulses ??? Stinebring et at. 1984
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OPM Depolarization (Xu.R.X) Orthogonal Poln Mode (OPM) →Depolarization (Low LP] ??? Or Low LP →OPM ???
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Daugherty & Lerche, 1975 The “Death line” of radio pulsars
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The Death line of radio pulsars
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Death and appearance line Qiao et al.,2003 Sparking condition ! Does not Hubble line!
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The Death line of radio pulsars Qiao & Zhang,1996
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The magnetosphere of a NS Critical field line NCS
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Low L Poln→OPM ? Xu & Qiao, 2000, Science in China
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Outer Gap Model Emission beams: 1 &4 : toward out side 2 & 3 : toward inside
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Muslimov & Harding, 2003 Slot gap model
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Beams in ICS model Type I Type II Qiao,Liu,Zhang & Han, 2001
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Obs. & ICS : Type I a Obs.ICS Qiao,Liu, Zhang,& Han, 2001,AA Lyne & Manchester (1988) & Sieber et al. (1975)
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Obs. & ICS: Type Ib Obs. ICS Qiao,Liu, Zhang,& Han, 2001,AA Kramer (1994).
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Obs. & ICS : Type IIa ICS Obs. Qiao,Liu, Zhang,& Han, 2001,AAPhillips & Wolszczan (1992).
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Magnetospere of pulsars Am--mass of ion, Z-charge of ion Outer gap, 1 Space charge limited flow Inner gap
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Holloway 1975 MN
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Poln. of Individual pulses in ICS model Xu,Liu,Han,Qiao, 2000, ApJ
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Radio emission of pulsars Observations & Theories ☆ Emission beams: Core+Cones Emission locations ☆ Polarization: linear, circular, “orthogonal mode” ☆ Pulse profiles changing with frequencies
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Rankin (1983, 1993) Gil & Krawczyk 1996; Mitra & Deshpande 1999; Gangadhara & Gupta 2001, Lyne & Manchester 1988 Han & Manchester 2001 Core and Cones
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ω=2γ 2 ω 0 (1-βCosθ i ) ICS model: The low frequency wave can Propagate near the surface Qiao & Lin, 1998, AA
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Polar Cap Model
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Inner annular gap Qiao,Lee,Wang,Xu, 2003
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Gamma-ray +radio emission Radio + Gamma ray emission model ☆ Basic picture ☆ Pulse profiles fitting: radio + Gamma-rays
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Gamma-ray emission of pulsars ● Current models ☆ Polar cap model ☆ Outer gap model ● Radio + Gamma ray emission model ☆ Basic picture ☆ Pulse profiles fitting: radio + Gamma-rays
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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
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● Gamma-ray OBS. Of Radio Pulsars
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Janssenet al. astr-ph/0406484: PSR B1818-13
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