The study of young galactic supernovae through 44Ti gamma-ray line emission with Integral

In this paper, we present the results of a study of galactic supernovae (SNe) through the observation of ⁴⁴Ti γ-ray lines with INTEGRAL. This radioactive nucleus, mainly produced in the inner layers of SNe, has a lifetime of about 85 years and emits three γ-ray lines at 67.9, 78.4 and 1157 keV with similar branching ratios. Exempt of interstellar extinction limitations, it is a useful tool to study young SNe and constrain the models of explosive nucleosynthesis. Firstly, we report the results on the young historical SNe of known age, namely Kepler (SN1604) and Tycho (SN1572). Then we present the results of a search for young hidden SNe in the Galactic central region and discuss their implications in terms of SNe rate and ⁴⁴Ti yield per event. Finally the results of a search for ⁴⁴Ti line emission from the Vela Junior supernova remnant are reported.