Using 44Ti emission to differentiate between thermonuclear supernova progenitors

Abstract

The radioisotope 44Ti is produced through α-rich freezeout and explosive helium burning in type Ia supernovae (SNe Ia). In this paper, we discuss how the detection of 44Ti, 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 44Ti 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-MCh) and near-Chandrasekhar (near-MCh) SNe Ia. In addition, we predict that the late-time light curves of calcium-rich transients are entirely dominated by 44Ti.