Quantum Effects in Magnetized Electron-Positron Plasmas: Synchrotron Pair Cascades and Gamma-ray Burst Spectra
Modelling of gamma-ray burst spectra with optically thin synchrotron emission in strong magnetic fields is examined. The properties of burst sources that suggest the existence of electron-positron pairs and strong magnetic fields in the emission region are summarized. In such a field, interesting quantum processes occur, such as the creation of an electron-positron pair by a free photon and the splitting of a photon in two. These have a profound influence on the synchrotron emission modelling of the continuum of burst sources. The basic properties of these processes of these sources are reviewed. The spectrum is attenuated at gamma-ray energies, which may or may not be observed. Pairs that are created by photons can reradiate synchrotron photons at lower energies that may create further pairs. The process can continue forming a pair cascade. The equilibrium spectra from such cascades are calculated to see what modifications the pair creation makes to the hard X-ray synchrotron spectrum: it is found that the spectral index does not change from that expected without any pair production. The distribution of angles of radiation and particles with respect to the direction of the magnetic field is also considered, and it is found that accurate fitting of hard gamma-ray burst spectra above 1 MeV is possible.
KeywordsNeutron Star Pair Production Optical Depth Spectral Index Strong Magnetic Field
Unable to display preview. Download preview PDF.
- Baring, M. G.: 1989b Mon. Not Roy. astr. Soc. submittedGoogle Scholar
- Bussard, R. W., and Lamb, F. K.: 1982 in Gamma Ray Transients and Related Astrophysical Phenomena eds. Lingenfelter, R. E., et al., ( AIP, New York ) p 189Google Scholar
- Epstein, R., 1986 in Radiative Hydronamics in Stars and Compact Objects eds. Winkler, W., H., and Mihalas, D., ( Springer, Heidelberg )Google Scholar
- Heuter, G. J.: 1984 in High Energy Transients in Astrophysics ed. Woosley, S. E., ( AIP, New York ) p 373Google Scholar
- Nolan, P. L., et al..: 1983 in Positron-Electron Pairs in Astrophysics, eds: Burns, M. L., et al., ( AIP, New York ) p 59Google Scholar
- Nolan, P. L., et al..: 1984 in High Energy Transients in Astrophysics ed. Woosley, S. E., ( AIP, New York ) p 399Google Scholar
- Sokolov, A. A., and Ternov, I. M.: 1968 Synchrotron Radiation ( Pergamon Press, Oxford )Google Scholar