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Gamma-Ray Constraints On Supernova Nucleosynthesis, Mark D. Leising
Gamma-Ray Constraints On Supernova Nucleosynthesis, Mark D. Leising
Publications
Gamma-ray spectroscopy holds great promise for probing nucleosynthesis in individual supernova explosions via short-lived radioactivity, and for measuring current global Galactic supernova nucleosynthesis with longer-lived radioactivity. It was somewhat surprising that the former case was realized first for a Type II supernova, when both Co-56 and Co-57 were detected in SN 1987A. These provide unprecedented constraints on models of Type II explosions and nucleosynthesis. Live Al-26 in the Galaxy might come from Type II supernovae, and if it is eventually shown to be so, can constrain massive star evolution, supernova nucleosynthesis, and the Galactic Type II supernova rate. Type Ia …
A Search For Gamma-Ray Lines From The Decay Of Fe-59 In Supernova 1987a, Mark D. Leising, M J. Harris
A Search For Gamma-Ray Lines From The Decay Of Fe-59 In Supernova 1987a, Mark D. Leising, M J. Harris
Publications
We have searched spectra of Supernova (SN) 1987A, accumulated during several 35-day intervals after the explosion by the Solar Maximum Mission (SMM) Gamma Ray Spectrometer (GRS), for gamma-ray lines at 1.099 and 1.292 MeV from the decay of Fe-59 which may have been produced in the progenitor's helium shell. We find no evidence for these lines, down to 3-sigma upper limits approximately = 7 x 10-4 gamma/sq cm/s for the 1.099 MeV line, or approximately = 4.5 x 10-4 gamma/sq cm/s for the 1.292 MeV line, in any 35-day interval. We derive a conservative 3-sigma upper limit on the mass …
The Cosmic Gamma-Ray Background From Type Ia Supernovae, Mark D. Leising, Donald D. Clayton, Lih-Sin The
The Cosmic Gamma-Ray Background From Type Ia Supernovae, Mark D. Leising, Donald D. Clayton, Lih-Sin The
Publications
We present an improved calculation of the cumulative gamma-ray spectrum of Type Ia supernovae during the history of the universe. We follow Clayton & Ward (1975) in using a few Friedmann models and two simple histories of the average galaxian nucleosynthesis rate, but we improve their calculation by modeling the gamma-ray scattering in detailed numerical models of SN Ia's. The results confirm that near 1 MeV the SN Ia background may dominate, and that it is potentially observable, with high scientific importance. A very accurate measurement of the cosmic background spectrum between 0.1 and 1.0 MeV may reveal the turn-on …
Search For Gamma-Ray Transients Using The Smm Spectrometer, Mark D. Leising, G H. Share, M J. Harris, D C. Messina
Search For Gamma-Ray Transients Using The Smm Spectrometer, Mark D. Leising, G H. Share, M J. Harris, D C. Messina
Publications
Observations for transient radiation made by the Gamma Ray Spectrometer on the SMM satellite are summarized. Spectra were obtained from 215 solar flares and 177 gamma-ray bursts. No narrow or moderately broadened lines were observed in any of the bursts. The rate of bursts is consistent with a constant over the mission but is weakly correlated with solar activity. No evidence was found for bursts of 511 keV line emission, unaccompanied by a strong continuum, at levels not less than 0.05 gamma/sq cm s for bursts lasting not more than 16 s. No evidence was found for broad features near …