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Gamma-Ray Signatures of Supernovae and Hypernovae

K. Nomoto·K. Maeda·Y. Mochizuki·S. Kumagai·H. Umeda·T. Nakamura·I. Tanihata
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Abstract

We review the characteristics of nucleosynthesis and radioactivities in 'Hypernovae', i.e., supernovae with very large explosion energies ($ \gsim 10^{52} $ ergs) and their $γ$-ray line signatures. We also discuss the $^{44}$Ti line $γ$-rays from SN1987A and the detectability with INTEGRAL. Signatures of hypernova nucleosynthesis are seen in the large [(Ti, Zn)/Fe] ratios in very metal poor stars. Radioactivities in hypernovae compared to those of ordinary core-collapse supernovae show the following characteristics: 1) The complete Si burning region is more extended, so that the ejected mass of $^{56}$Ni can be much larger. 2) Si-burning takes place in higher entropy and more $α$-rich environment. Thus the $^{44}$Ti abundance relative to $^{56}$Ni is much larger. In aspherical explosions, $^{44}$Ti is even more abundant and ejected with velocities as high as $\sim$ 15,000 km s$^{-1}$, which could be observed in $γ$-ray line profiles. 3) The abundance of $^{26}$Al is not so sensitive to the explosion energy, while the $^{60}$Fe abundance is enhanced by a factor of $\sim$ 3.

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K. Nomoto, K. Maeda, Y. Mochizuki, S. Kumagai, H. Umeda, T. Nakamura, I. Tanihata. 2001-10-03. Gamma-Ray Signatures of Supernovae and Hypernovae. https://doi.org/10.1063/1.1419452

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