Between 1980 February and 1983 August the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission satellite (SMM) observed 71 gamma-ray bursts. These events form a representative subset of the class of classical gamma-ray bursts. Since their discovery more than 15 years ago, hundreds of gamma-ray bursts have been detected; however, most observations have been limited to an energy range of roughly 30 keV-1MeV. The large sensitive area and spectral range of the GRS allow, for the first time, an investigation of the high-energy (>1 MeV) behavior of a substantial number of gamma-ray bursts.
It is found that high-energy emission is seen in a large fraction of all events and that the data are consistent with all bursts emitting to at least 5 MeV with no cut-offs. Further, no burst spectrum measured by GRS has a clear high-energy cut-off. The high-energy emission can be a significant part of the total burst energy; on the average about 30% of the observed energy above 30 keV is contained in the >1 MeV photons.
Tests of spectral models yield mixed results. Neither a power law nor a thermal model can adequately explain all of the observed spectra. Some GRS spectra show clear curvature and cannot be well-fit by a power law. However, a number of spectra are clearly power laws, and the power-law model is consistent with more events ((TURN)80%) than either thermal synchrotron or optically-thin thermal bremsstrahlung. In addition, the two thermal models are generally too soft to explain the observed high-energy emission.
The fact that the observations are consistent with the presence of high-energy emission in all events implies a limit on the preferential beaming of high-energy photons, from any mechanism. Single-photon pair-production in a strong magnetic field produces such beaming; assuming that the low-energy emission is isotropic, the data imply an upper limit of 1 x 10('12) G on the typical magnetic field at burst radiation sites.
","abstract_html":"<p>Between 1980 February and 1983 August the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission satellite (SMM) observed 71 gamma-ray bursts. These events form a representative subset of the class of classical gamma-ray bursts. Since their discovery more than 15 years ago, hundreds of gamma-ray bursts have been detected; however, most observations have been limited to an energy range of roughly 30 keV-1MeV. The large sensitive area and spectral range of the GRS allow, for the first time, an investigation of the high-energy (>1 MeV) behavior of a substantial number of gamma-ray bursts.</p><p>It is found that high-energy emission is seen in a large fraction of all events and that the data are consistent with all bursts emitting to at least 5 MeV with no cut-offs. Further, no burst spectrum measured by GRS has a clear high-energy cut-off. The high-energy emission can be a significant part of the total burst energy; on the average about 30% of the observed energy above 30 keV is contained in the >1 MeV photons.</p><p>Tests of spectral models yield mixed results. Neither a power law nor a thermal model can adequately explain all of the observed spectra. Some GRS spectra show clear curvature and cannot be well-fit by a power law. However, a number of spectra are clearly power laws, and the power-law model is consistent with more events ((TURN)80%) than either thermal synchrotron or optically-thin thermal bremsstrahlung. In addition, the two thermal models are generally too soft to explain the observed high-energy emission.</p><p>The fact that the observations are consistent with the presence of high-energy emission in all events implies a limit on the preferential beaming of high-energy photons, from any mechanism. Single-photon pair-production in a strong magnetic field produces such beaming; assuming that the low-energy emission is isotropic, the data imply an upper limit of 1 x 10('12) G on the typical magnetic field at burst radiation sites.</p>","abstract_has_math":false,"creators":["MATZ, STEVEN MICHAEL"],"institution":null,"degree_name":"Doctor of Philosophy","degree_level":"Dissertation","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1986,"date_issued":"1986-01-01T08:00:00Z","date_published":"1986-01-01T08:00:00Z","updated_at":"2026-07-24T05:23:21Z","subjects":["Physics","Astronomy and Astrophysics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholars.unh.edu/dissertation/1483","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["MATZ, STEVEN MICHAEL"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physics","Astronomy and Astrophysics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholars.unh.edu/dissertation/1483"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Between 1980 February and 1983 August the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission satellite (SMM) observed 71 gamma-ray bursts. These events form a representative subset of the class of classical gamma-ray bursts. Since their discovery more than 15 years ago, hundreds of gamma-ray bursts have been detected; however, most observations have been limited to an energy range of roughly 30 keV-1MeV. The large sensitive area and spectral range of the GRS allow, for the first time, an investigation of the high-energy (>1 MeV) behavior of a substantial number of gamma-ray bursts.
It is found that high-energy emission is seen in a large fraction of all events and that the data are consistent with all bursts emitting to at least 5 MeV with no cut-offs. Further, no burst spectrum measured by GRS has a clear high-energy cut-off. The high-energy emission can be a significant part of the total burst energy; on the average about 30% of the observed energy above 30 keV is contained in the >1 MeV photons.
Tests of spectral models yield mixed results. Neither a power law nor a thermal model can adequately explain all of the observed spectra. Some GRS spectra show clear curvature and cannot be well-fit by a power law. However, a number of spectra are clearly power laws, and the power-law model is consistent with more events ((TURN)80%) than either thermal synchrotron or optically-thin thermal bremsstrahlung. In addition, the two thermal models are generally too soft to explain the observed high-energy emission.
The fact that the observations are consistent with the presence of high-energy emission in all events implies a limit on the preferential beaming of high-energy photons, from any mechanism. Single-photon pair-production in a strong magnetic field produces such beaming; assuming that the low-energy emission is isotropic, the data imply an upper limit of 1 x 10('12) G on the typical magnetic field at burst radiation sites.
"]},{"key":"dc:title","label":"Title","values":["ON THE SPECTRA OF GAMMA-RAY BURSTS AT HIGH ENERGIES"]}]}],"canonical_facts":{"dc:creator":["MATZ, STEVEN MICHAEL"],"dc:description.abstract":["Between 1980 February and 1983 August the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission satellite (SMM) observed 71 gamma-ray bursts. These events form a representative subset of the class of classical gamma-ray bursts. Since their discovery more than 15 years ago, hundreds of gamma-ray bursts have been detected; however, most observations have been limited to an energy range of roughly 30 keV-1MeV. The large sensitive area and spectral range of the GRS allow, for the first time, an investigation of the high-energy (>1 MeV) behavior of a substantial number of gamma-ray bursts.
It is found that high-energy emission is seen in a large fraction of all events and that the data are consistent with all bursts emitting to at least 5 MeV with no cut-offs. Further, no burst spectrum measured by GRS has a clear high-energy cut-off. The high-energy emission can be a significant part of the total burst energy; on the average about 30% of the observed energy above 30 keV is contained in the >1 MeV photons.
Tests of spectral models yield mixed results. Neither a power law nor a thermal model can adequately explain all of the observed spectra. Some GRS spectra show clear curvature and cannot be well-fit by a power law. However, a number of spectra are clearly power laws, and the power-law model is consistent with more events ((TURN)80%) than either thermal synchrotron or optically-thin thermal bremsstrahlung. In addition, the two thermal models are generally too soft to explain the observed high-energy emission.
The fact that the observations are consistent with the presence of high-energy emission in all events implies a limit on the preferential beaming of high-energy photons, from any mechanism. Single-photon pair-production in a strong magnetic field produces such beaming; assuming that the low-energy emission is isotropic, the data imply an upper limit of 1 x 10('12) G on the typical magnetic field at burst radiation sites.
"],"dc:identifier":["https://scholars.unh.edu/dissertation/1483"],"dc:subject":["Physics","Astronomy and Astrophysics"],"dc:title":["ON THE SPECTRA OF GAMMA-RAY BURSTS AT HIGH ENERGIES"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy"]},"updated_at":"2026-07-24T05:23:21Z"}