Annihilation radiation from a power-law distributed electron-positron plasma on the ground Landau level: the case of low magnetic fields |
| |
Authors: | A D Kaminker G G Pavlov P G Mamradze |
| |
Institution: | (1) A.F. Ioffe Institute of Physics and Technology, St. Petersburg, Russia;(2) Abastumani Astrophysical Observatory, Tbilisi, Georgia |
| |
Abstract: | Intensity, polarization, and cooling rate of the two-photon annihilation radiation are studied in detail in the case of one-dimensional power-law distributions of electrons and positrons, assuming that they occupy the ground Landau level in a strong magnetic fieldB 1010–1012 G. Simple analytical expressions for limiting cases are obtained and results of numerical calculations of radiation characteristics are presented. Power-lawe
± distributions
±
±
–k
are shown to generate power-law spectra of the annihilation radiation atE mc
2 andE mc
2, with indices depending on the direction of radiation. The annihilation spectra at =0 show the largest blue-shifts of their maxima and the hardest high-energy tailsI(E mc
2, =0) E
–(k–1). The blue-shifts reduce, and the hard tials steepen, with increasing . At >(2mc
2/E)1/2 the slopes of the high-energy tails rapidly transform to that at = 2,I(E mc
2, = /2) E
–(2k+3). The direction-integrated spectraS(E) also display the power-law tials at low and high energies,S(E mc
2) E
–(k+1). The total annihilation rate and energy losses decrease with decreasingk, being higher than for the isotropice
± power-law distributions at the samek. The radiation is linearly polarized in the plane formed by the magnetic field and wave-vector. The polarization degreeP is maximum atE mc
2:P
max 0.6 for = /2. Annihilation features and power-law-like hard tails observed in many gamma-ray burst spectra may be associated with the annihilation radiation of the magnetized power-law distributed plasma near neutron stars. Comparison of the observed and theoretical spectra allows one to estimate the power-law index of thee
–
e
+-distribution and the gravitational redshift factor in the radiating region. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|