Annihilation radiation from thermal electron-positron plasma on the ground Landau level: The case of low magnetic fields

A. D. Kaminker, George Pavlov, P. G. Mamradze

Research output: Contribution to journalArticle

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Abstract

The intensity and polarization of two-photon annihilation in a magnetic fuield B≪Bcr=4.4×1013 G are studied in detail for a, one-dimensional thermal distribution of annihilating electrons and positrons on the ground Landau level. With the increase of temperature T the total annihilation rate and energy losses decrease, being higher than for the isotropic thermal distributions at the same T. The shapes of intensity spectra at sin ρ{variant}=0 (ρ{variant} is the angle between B and wave-vector) are close to those in the isotropic case. The widths and blue-shifts of the spectra decrease with increasing sin ρ{variant} and increase with increasing T. Logarthmic singularities arise in the spectra at E»mc2/sin ρ{variant}. Power-like parts are formed in the wings of the spectra for kT≫mc2 and not too small sin ρ{variant}. The direction-integrated spectra reach their (finite) maxima, at E=mc2 for any T. The radiation concentrates near the plane, perpendicular to the magnetic field for E close to mc2 and is beamed along the magnetic field for E far from mc2. Energy-integrated angular distributions are stretched along B, the stronger the higher T. The rediation is linearly polarized in the plane formed by the magnetic field and weve-vector. Typical values of the polarization inside the cores of the annihilation spectra are ∼(kT/mc2) sin ρ{variant} and [ln (kT/mc2)]-1 for kT≪mc2 and kT sin ρ{variant}≫mc2, respectively. Annihilation radiation dominates over Bremsstrahlung in the e plasma at kT≲7 mc2. The results are useful for interpretation of the annihilation radiation in the gamma-ray bursts. They permit to estimate temperature, gravitational potential, and emission measure of radiating regions and the beaming of the radiation.

Original languageEnglish (US)
Pages (from-to)241-284
Number of pages44
JournalAstrophysics and Space Science
Volume174
Issue number2
DOIs
StatePublished - Dec 1 1990

Fingerprint

electron-positron plasmas
thermal plasmas
magnetic field
plasma
electron
radiation
magnetic fields
polarization
potential temperature
gamma ray bursts
blue shift
wings
bremsstrahlung
gravitational fields
energy
positrons
angular distribution
energy dissipation
temperature
photons

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

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title = "Annihilation radiation from thermal electron-positron plasma on the ground Landau level: The case of low magnetic fields",
abstract = "The intensity and polarization of two-photon annihilation in a magnetic fuield B≪Bcr=4.4×1013 G are studied in detail for a, one-dimensional thermal distribution of annihilating electrons and positrons on the ground Landau level. With the increase of temperature T the total annihilation rate and energy losses decrease, being higher than for the isotropic thermal distributions at the same T. The shapes of intensity spectra at sin ρ{variant}=0 (ρ{variant} is the angle between B and wave-vector) are close to those in the isotropic case. The widths and blue-shifts of the spectra decrease with increasing sin ρ{variant} and increase with increasing T. Logarthmic singularities arise in the spectra at E»mc2/sin ρ{variant}. Power-like parts are formed in the wings of the spectra for kT≫mc2 and not too small sin ρ{variant}. The direction-integrated spectra reach their (finite) maxima, at E=mc2 for any T. The radiation concentrates near the plane, perpendicular to the magnetic field for E close to mc2 and is beamed along the magnetic field for E far from mc2. Energy-integrated angular distributions are stretched along B, the stronger the higher T. The rediation is linearly polarized in the plane formed by the magnetic field and weve-vector. Typical values of the polarization inside the cores of the annihilation spectra are ∼(kT/mc2) sin ρ{variant} and [ln (kT/mc2)]-1 for kT≪mc2 and kT sin ρ{variant}≫mc2, respectively. Annihilation radiation dominates over Bremsstrahlung in the e∓ plasma at kT≲7 mc2. The results are useful for interpretation of the annihilation radiation in the gamma-ray bursts. They permit to estimate temperature, gravitational potential, and emission measure of radiating regions and the beaming of the radiation.",
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Annihilation radiation from thermal electron-positron plasma on the ground Landau level : The case of low magnetic fields. / Kaminker, A. D.; Pavlov, George; Mamradze, P. G.

In: Astrophysics and Space Science, Vol. 174, No. 2, 01.12.1990, p. 241-284.

Research output: Contribution to journalArticle

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AB - The intensity and polarization of two-photon annihilation in a magnetic fuield B≪Bcr=4.4×1013 G are studied in detail for a, one-dimensional thermal distribution of annihilating electrons and positrons on the ground Landau level. With the increase of temperature T the total annihilation rate and energy losses decrease, being higher than for the isotropic thermal distributions at the same T. The shapes of intensity spectra at sin ρ{variant}=0 (ρ{variant} is the angle between B and wave-vector) are close to those in the isotropic case. The widths and blue-shifts of the spectra decrease with increasing sin ρ{variant} and increase with increasing T. Logarthmic singularities arise in the spectra at E»mc2/sin ρ{variant}. Power-like parts are formed in the wings of the spectra for kT≫mc2 and not too small sin ρ{variant}. The direction-integrated spectra reach their (finite) maxima, at E=mc2 for any T. The radiation concentrates near the plane, perpendicular to the magnetic field for E close to mc2 and is beamed along the magnetic field for E far from mc2. Energy-integrated angular distributions are stretched along B, the stronger the higher T. The rediation is linearly polarized in the plane formed by the magnetic field and weve-vector. Typical values of the polarization inside the cores of the annihilation spectra are ∼(kT/mc2) sin ρ{variant} and [ln (kT/mc2)]-1 for kT≪mc2 and kT sin ρ{variant}≫mc2, respectively. Annihilation radiation dominates over Bremsstrahlung in the e∓ plasma at kT≲7 mc2. The results are useful for interpretation of the annihilation radiation in the gamma-ray bursts. They permit to estimate temperature, gravitational potential, and emission measure of radiating regions and the beaming of the radiation.

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