Continuum spectra for gamma-ray bursts: Suppressing the soft photons

Conference · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5763476

Ho, Cheng; Epstein, R I

Gamma-ray bursts are observed to have very steep spectra below photon energy /approximately/100 keV; some have photon number spectra as steep as F /proportional to/ E/sup 0/. This property has been difficult to explain in terms of most radiation processes. The BATSE experiment on the Gamma Ray Observatory should be able to test how common this spectral property is and whether there are bursts with even steeper low-energy spectra. To explain this spectral steepness, we study a model in which the /gamma/ radiation is produced by inverse-Compton and cyclotron scattering of blackbody radiation from the surface of a neutron star by relativistic electrons. If the neutron star has negligible magnetic field, Compton scattering dominates in producing the observed gamma-ray burst spectra. If the field exceeds 10/sup 10/ G, cyclotron scattering is more important. In the low-magnetic-field case, steep spectra may be produced via the suppression of the low energy part of the ''cooling spectrum'' (the spectrum integrated over the radiation lifetime of an electron), as a result of the smaller and more collimated photon flux an electron sees as it moves away from the neutron star. In the high-magnetic-field case, low-energy suppression occurs because electrons with higher energies scatter the blackbody photons more efficiently due to the cyclotron resonance, preferentially producing high energy photons. 27 refs., 5 figs.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5763476
• Report Number(s): LA-UR-89-2384; CONF-8904216-5; ON: DE89015260
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
640102 -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BASIC INTERACTIONS
COMPTON EFFECT
COSMIC GAMMA BURSTS
COSMIC RADIATION
CROSS SECTIONS
CYCLOTRON RESONANCE
ELASTIC SCATTERING
ELECTROMAGNETIC INTERACTIONS
ENERGY SPECTRA
INTERACTIONS
IONIZING RADIATIONS
MAGNETIC FIELDS
NEUTRON STARS
PARTICLE INTERACTIONS
PHOTON-ELECTRON INTERACTIONS
PHOTON-LEPTON INTERACTIONS
PRIMARY COSMIC RADIATION
RADIATIONS
RESONANCE
SCATTERING
SPECTRA
STARS