### Abstract

The intensity and polarization of two-photon annihilation in a magnetic fuield B≪B_{cr}=4.4×10^{13} 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»mc^{2}/sin ρ{variant}. Power-like parts are formed in the wings of the spectra for kT≫mc^{2} and not too small sin ρ{variant}. The direction-integrated spectra reach their (finite) maxima, at E=mc^{2} for any T. The radiation concentrates near the plane, perpendicular to the magnetic field for E close to mc^{2} and is beamed along the magnetic field for E far from mc^{2}. 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/mc^{2}) sin ρ{variant} and [ln (kT/mc^{2})]^{-1} for kT≪mc^{2} and kT sin ρ{variant}≫mc^{2}, respectively. Annihilation radiation dominates over Bremsstrahlung in the e^{∓} plasma at kT≲7 mc^{2}. 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 language | English (US) |
---|---|

Pages (from-to) | 241-284 |

Number of pages | 44 |

Journal | Astrophysics and Space Science |

Volume | 174 |

Issue number | 2 |

DOIs | |

State | Published - Dec 1 1990 |

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### All Science Journal Classification (ASJC) codes

- Astronomy and Astrophysics
- Space and Planetary Science

### Cite this

*Astrophysics and Space Science*,

*174*(2), 241-284. https://doi.org/10.1007/BF00642511

}

*Astrophysics and Space Science*, vol. 174, no. 2, pp. 241-284. https://doi.org/10.1007/BF00642511

**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.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Annihilation radiation from thermal electron-positron plasma on the ground Landau level

T2 - The case of low magnetic fields

AU - Kaminker, A. D.

AU - Pavlov, George

AU - Mamradze, P. G.

PY - 1990/12/1

Y1 - 1990/12/1

N2 - 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.

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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U2 - 10.1007/BF00642511

DO - 10.1007/BF00642511

M3 - Article

AN - SCOPUS:34249953359

VL - 174

SP - 241

EP - 284

JO - Astrophysics and Space Science

JF - Astrophysics and Space Science

SN - 0004-640X

IS - 2

ER -