Left panel: comparison of upper limits and detection of Cassiopeia A with predictions made from core-collapse supernova models. Right panel: predicted ⁴⁴Ti ejecta yields for different type Ia supernova models. Upper limits obtained for the three youngest type Ia supernovae exclude the double detonation model and faint SN2005E-like scenarios. We include the detections of ⁴⁴Ti in Cassiopeia A and SN1987 A with the NuSTAR and INTEGRAL/IBIS telescopes in green and blue, respectively. Upper limits from further NuSTAR and IBIS observation are additionally included in green and blue (see Table 3 for references). Masses are determined for the distances in Table 1 and remnant age at the average observation date in the cited publications.