Pair formation above pulsar polar caps - Structure of the low altitude acceleration zone

1979 ◽  
Vol 231 ◽  
pp. 854 ◽  
Author(s):  
J. Arons ◽  
E. T. Scharlemann
Keyword(s):  
Pair Formation ◽  
Polar Caps ◽  
Acceleration Zone ◽  
Low Altitude

scholarly journals Compton scattering effect on polar gap formation: Self-sustained polar cap heating

1996 ◽  
Vol 160 ◽  
pp. 175-176
Author(s):  
Qinghuan Luo
Keyword(s):  
Compton Scattering ◽  
Maximum Energy ◽  
Gap Formation ◽  
Inverse Compton Scattering ◽  
Polar Caps ◽  
Primary Particles ◽  
Polar Gap ◽  
Acceleration Zone ◽  
Gap Height ◽  
Gap Models

One of the essential ingredients in existing polar gap models (e.g. Ruderman & Sutherland 1975; Arons & Scharlemann 1979, hereafter AS) is a pair cascade above polar caps. In these models, pair cascade is initiated by curvature photons radiated by primary particles and produced pairs screen out the electric field, forming a pair-production-limited acceleration zone (called the polar gap). For pulsars with strong magnetic fields (B≳ 1012G) and hot polar caps, resonant inverse Compton scattering (RICS) can be important (e.g. Dermer 1990; Sturner 1995, and references therein). The gap height is significantly reduced by the RICS effect (Luo 1996), and this may reduce the energetics of the polar gap as the maximum energy of primary particles is constrained by the gap height. The minimum temperature for RICS to be important is (Luo 1996)

Particle Acceleration Zones above Pulsar Polar Caps: Electron and Positron Pair Formation Fronts

1998 ◽  
Vol 508 (1) ◽  
pp. 328-346 ◽  
Author(s):  
Alice K. Harding ◽  
Alexander G. Muslimov
Keyword(s):  
Particle Acceleration ◽  
Pair Formation ◽  
Polar Caps

scholarly journals Pulsar Death at an Advanced Age

1996 ◽  
Vol 160 ◽  
pp. 177-178
Author(s):  
Jonathan Arons
Keyword(s):  
Radio Emission ◽  
Large Scale ◽  
High Energy ◽  
Pair Creation ◽  
High Energy Particle ◽  
Polar Cap ◽  
Pulsar Radio ◽  
Polar Caps ◽  
Low Altitude ◽  
Pulsar Radio Emission

Not long ago Rankin (1990) presented strong evidence in favor of a low altitude (r≈R*) dipole geometry for the site of the core component of pulsar radio emission. Arons (1993) gave evidence that spun up millisecond pulsars must have a substantially dipolar large scale field at low altitute. Electron-positron pair creation at low altitude above the polar caps has long been hypothesized to be an essential ingredient of pulsar radio emission. If so, all observed pulsars must lie in the region ofP−Ṗspace where polar cap acceleration has sufficient vigor to lead to the copious pair production. Yet, to date, allinternally consistenttheories of polar cap pair creation have required hypothesizing a large scale (eg, quadrupole) component of the magnetic field with strength comparable to that of the dipole, in contradiction with the evidence in favor of an apparently dipolar low altitude geometry. The internally consistent theories also violate other observational constraints. The discharge models of Ruderman and Sutherland (1975), Gurevich and Istomin (1985), and Jones (1977, 1978, 1979) all accelerate equal, counterstreaming flows of electrons and positrons, thus putting one half of the particle acceleration energy into high energy particle and photon bombardment of the polar caps. The heating causes pulsed thermal X-ray emission from hot spots in excess of what is seen (Ogelman 1993). While the Arons and Scharlemann (1979) model does not have this problem, since the space charge in the starvation zone above the polar cap is made up almost entirely of the outbound beam, in star centered dipole geometry it dramatically fails to account for pulsar emission over most of theP−Ṗdiagram and predicts radio polarization variations in contradiction to the observations (Narayan and Vivekanand 1982).

Solar Flare Energetic Neutral Emission Measurements in the Project Coronas-I

1994 ◽  
Vol 144 ◽  
pp. 635-639
Author(s):  
J. Baláž ◽  
A. V. Dmitriev ◽  
M. A. Kovalevskaya ◽  
K. Kudela ◽  
S. N. Kuznetsov ◽  
...  
Keyword(s):  
Solar Flare ◽  
Energy Range ◽  
Gamma Rays ◽  
Pulse Shape ◽  
Gamma Ray ◽  
Pulse Shape Discrimination ◽  
Shape Discrimination ◽  
Solar Neutron ◽  
Low Altitude

AbstractThe experiment SONG (SOlar Neutron and Gamma rays) for the low altitude satellite CORONAS-I is described. The instrument is capable to provide gamma-ray line and continuum detection in the energy range 0.1 – 100 MeV as well as detection of neutrons with energies above 30 MeV. As a by-product, the electrons in the range 11 – 108 MeV will be measured too. The pulse shape discrimination technique (PSD) is used.

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