Non-stationary pair plasma in a pulsar magnetosphere and the two-stream instability

被引:93
作者
Asseo, E [1 ]
Melikidze, GI
机构
[1] Ecole Polytech, Ctr Phys Theor, F-91128 Palaiseau, France
[2] Ctr Astron, PL-65265 Zielona Gora, Poland
[3] Abastumani Astrophys Observ, GE-380060 Tbilisi, Georgia
关键词
instabilities; plasmas; radiation mechanisms : non-thermal; pulsars : general;
D O I
10.1046/j.1365-8711.1998.01990.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We test a new emission mechanism in pulsar magnetospheres, eventually responsible in part for the high level of observed radio radiation. This is carried out by comparing the efficiency of the two-stream instability of Langmuir waves in a pulsar emission region, where the stationary and non-stationary characters of pair plasma outflows produced in the gap region are characterized by two different time-scales. On the shorter time-scale, the Ruderman & Sutherland 'sparking' phenomenon leads to the creation of pair plasma clouds, in motion along magnetic field lines, that contain particles with a large spectrum of momenta. The overlapping of particles with different energies produced in successive clouds results in an efficient 'two stream'-like instability. This effect is a consequence of the non-stationary character of the pair plasma produced in the gap region, just above the magnetic poles of the neutron star. On a long ti:me-scale, resulting pair plasma outflows in pulsar magnetospheres can be treated as stationary In this case, the instability which results from interaction between existing primary beam particles and the pair plasma is negligible, whereas the instability owing to interaction between electrons and positrons of the pair plasma itself, and more precisely to their relative drift motion along curved magnetic field lines, is effective. We derive characteristic features of the triggered instability, using specific distribution functions to describe either particles in the assembly of clouds or relative drifting of electrons and positrons in these same plasma clouds. Although linear and local, our treatment suggests that nonstationary effects may compete with, or even dominate over, drifting effects in parts of pulsar emission regions.
引用
收藏
页码:59 / 71
页数:13
相关论文
共 33 条
[1]   WAVE-PROPAGATION IN PULSAR MAGNETOSPHERES - DISPERSION-RELATIONS AND NORMAL-MODES OF PLASMAS IN SUPERSTRONG MAGNETIC-FIELDS [J].
ARONS, J ;
BARNARD, JJ .
ASTROPHYSICAL JOURNAL, 1986, 302 (01) :120-137
[2]  
ARONS J, 1981, IAU S, V95, P69
[3]  
ASSEO E, 1990, MON NOT R ASTRON SOC, V247, P529
[4]  
ASSEO E, 1995, MON NOT R ASTRON SOC, V276, P74
[5]   RADIATIVE OR 2-STREAM INSTABILITY AS A SOURCE FOR PULSAR RADIO-EMISSION [J].
ASSEO, E ;
PELLAT, R ;
SOL, H .
ASTROPHYSICAL JOURNAL, 1983, 266 (01) :201-214
[6]  
Bliokh KY, 1996, ASTRON LETT+, V22, P482
[7]   TEMPERATURE STABILIZATION OF INSTABILITIES IN FORCE-FREE MAGNETOSPHERES [J].
BUSCHAUER, R ;
BENFORD, G .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1977, 179 (01) :99-103
[8]   BUNCHING MECHANISM FOR COHERENT CURVATURE RADIATION IN PULSAR MAGNETOSPHERES [J].
CHENG, AF ;
RUDERMAN, MA .
ASTROPHYSICAL JOURNAL, 1977, 212 (03) :800-806
[9]   PAIR PRODUCTION IN SUPERSTRONG MAGNETIC-FIELDS [J].
DAUGHERTY, JK ;
HARDING, AK .
ASTROPHYSICAL JOURNAL, 1983, 273 (02) :761-773
[10]  
DAUGHERTY JK, 1982, APJ, V252, P237