We review the characteristics of nucleosynthesis and radioactivities in Hypernovae, i.e., supernovae with very large explosion energies ($ gsim 10^{52} $ ergs) and their $gamma$-ray line signatures. We also discuss the $^{44}$Ti line $gamma$-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 $alpha$-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 $gamma$-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.
تحميل البحث