A brief introduction- Outer gap model of r-ray pulsar Department of Physics National Tsing Hua University Lun-Wen Yeh

The basic structure of the magnetosphere The basic structure of the magnetosphere Outer gap model Outer gap model Then …… Then …… Reference: 1.K.S.Cheng,C.Ho,M.Ruderman.1986,ApJ 2.V.S.Beskin,A.V.Gurevich,Ya.N.Istomin Physics of the pulsar magnetosphere.

The basic structure of the magnetosphere If the neutron star is a rotating magnetosphere with magnetic dipole moment. If the neutron star is a rotating magnetosphere with magnetic dipole moment. We assume the star which is perfect conductor. We assume the star which is perfect conductor. In the interior: In the interior: J=σ(E +v × B/c) E=-v × B/c J=σ(E +v × B/c) E=-v × B/c E·B=0 E·B=0 In the outside: In the outside: If it is vacuum E·B≠0 If it is vacuum E·B≠0 However E·B would exceed the component of the for gravitational force for an electron or a proton. However E·B would exceed the component of the for gravitational force for an electron or a proton. A rotating magnetic neutron star can not be surrounded by a vacuum!! A rotating magnetic neutron star can not be surrounded by a vacuum!! E · B≠0 E · B=0 ＾

The region surrounding the star is filled with plasma. We assume the plasma corotating with the neutron star as a rigid body. The region surrounding the star is filled with plasma. We assume the plasma corotating with the neutron star as a rigid body. E=-v × B/c (the same with the inside) E=-v × B/c (the same with the inside) ρ 0 = ( ▽ ·E)/4π=-Ω·B/2 πc [1-(Ωrsinθ /c) 2 ] ρ 0 = ( ▽ ·E)/4π=-Ω·B/2 πc [1-(Ωrsinθ /c) 2 ] B ~ [3(m·r)r-m]/r 3 B ~ [3(m·r)r-m]/r 3 ＾ ＾

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n c = ρ 0 /e (particle/cm 3 ) n c = ρ 0 /e (particle/cm 3 ) n c ~10 -6 (particle/cm 3 ) for earth n c ~10 -6 (particle/cm 3 ) for earth n c ~10 -5 (particle/cm 3 ) for Jupiter n c ~10 -5 (particle/cm 3 ) for Jupiter n c ~10 11 ~10 12 (particle/cm 3 ) for neutron star n c ~10 11 ~10 12 (particle/cm 3 ) for neutron star B~10 12 G B~10 12 G R~10 6 cm=10km R~10 6 cm=10km In the open field region there have flowing-current. In the open field region there have flowing-current.

Outer gap model In order to explain r-ray pulsar In order to explain r-ray pulsar polar cap polar cap outer gap (1986 Cheng, Ho, Ruderman) outer gap (1986 Cheng, Ho, Ruderman) We assume the current which flow through null-surface and result in the charges depletion in this region. We assume the current which flow through null-surface and result in the charges depletion in this region. In the gap E·B≠0 such that e± production mechanisms would create a pair plasma. In the gap E·B≠0 such that e± production mechanisms would create a pair plasma. Curvature radiation Curvature radiation Inverse Compton scattering Inverse Compton scattering Synchrotron radiation Synchrotron radiation ＾

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For the Crab and Vela pulsar most observes would detect two r-ray pulsars per period. For the Crab and Vela pulsar most observes would detect two r-ray pulsars per period. See See 1.Path difference 1.Path difference 2.Field bending 2.Field bending 3.Aberration 3.Aberration Two or Four Two or Four 1.Thickness 1.Thickness 2.Dip angles 2.Dip angles

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