Nebular spectra of 111 Type Ia supernovae

We find no evidence of stripped companion emission in any of the nebular-phase spectra. Upper limits are placed on the amount of mass that could go undetected in each spectrum using recent hydrodynamic simulations.

With these null detections, we place an observational 3{sigma} upper limit on the fraction of SNe Ia that are produced through the classical H-rich non-degenerate companion scenario of <5.5 per cent. Additionally, we set a tentative 3{sigma} upper limit on He star progenitor scenarios of <6.4 per cent, although further theoretical modelling is required. These limits refer to our most representative sample including normal, 91bg-like, 91T-like, and 'super-Chandrasekhar' SNe Ia but excluding SNe Iax and SNe Ia-CSM.