Defining Photometric Peculiar Type Ia Supernovae
  We present a new photometric identification technique for SN 1991bg-like type
Ia supernovae (SNe Ia), i.e. objects with light-curve characteristics such as
later primary maxima and absence of secondary peak in redder filters. This
method is capable of selecting out this sub-group from the normal type Ia
population. Furthermore, we find that recently identified peculiar sub-types
such as SNe Iax and super-Chandrasekhar SNe Ia have similar photometric
characteristics as 91bg-like SNe Ia, namely the absence of secondary maxima and
shoulders at longer wavelengths, and can also be classified with our technique.
The similarity of these different SN Ia sub-groups perhaps suggests common
physical conditions. This typing methodology permits the photometric
identification of peculiar SNe Ia in large up-coming wide field surveys either
to study them further or to obtain a pure sample of normal SNe Ia for
cosmological studies.
