Abstract
The radioisotope Ti-44 is produced through alpha-rich freezeout and explosive helium burning in type Ia supernovae (SNe Ia). In this paper, we discuss how the detection of Ti-44, either through late-time light curves of SNe Ia, or directly via gamma-rays, can uniquely constrain the origin of SNe Ia. In particular, building upon recent advances in the hydrodynamical simulation of helium-ignited double white dwarf binaries, we demonstrate that the detection of Ti-44 in a nearby SN Ia or in a young Galactic supernova remnant (SNR) can discriminate between the double-detonation and double-degenerate channels of sub-Chandrasekhar (sub-M-Ch) and near-Chandrasekhar (near-M-Ch) SNe Ia. In addition, we predict that the late-time light curves of calcium-rich transients are entirely dominated by Ti-44.