NDLI: Positron annihilation in gamma-ray bursts

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Positron annihilation in gamma-ray bursts

Content Provider	NASA Technical Reports Server (NTRS)
Author	Harding, Alice K.
Copyright Year	1990
Description	Emission features appear at energies of 350 to 450 keV in the spectra of a number of gamma ray burst sources. These features were interpreted as electron-positron annihilation lines, redshifted by the gravitational field near the surface of a neutron star. Evidence that gamma ray bursts originate at neutron stars with magnetic field strengths of approx. 10(exp 12) Gauss came from recent observations of cyclotron scattering harmonics in the spectra of two bursts. Positrons could be produced in gamma ray burst sources either by photon-photon pair production or by one-photon pair production in a strong magnetic field. The annihilation of positrons is affected by the presence of a strong neutron star magnetic field in several ways. The relaxation of transverse momentum conservation causes an intrinsic broadening of the two-photon annihilation line and there is a decrease in the annihilation cross section below the free-space value. An additional channel for one-photon annihilation also becomes possible in high magnetic fields. The physics of pair production and annihilation near strongly magnetized neutron stars will be reviewed. Results from a self-consistent model for non-thermal synchrotron radiation and pair annihilation are beginning to identify the conditions required to produce observable annihilation features from strongly magnetized plasmas.
File Size	879668
Page Count	16
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_19900009667
Archival Resource Key	ark:/13960/t71w0dq3t
Language	English
Publisher Date	1990-01-01
Access Restriction	Open
Subject Keyword	Space Radiation Magnetic Flux Harmonics Annihilation Reactions Stellar Magnetic Fields Red Shift Neutron Stars Plasmas Physics Gravitational Fields Positron Annihilation Gamma Ray Bursts Emission Spectra Positrons Pair Production Line Spectra Synchrotron Radiation Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science
Content Type	Text
Resource Type	Article

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