The Extremes of the Luminosity-Decline Rate Relation

The peak luminosity–decline rate relationship for Type Ia supernovae is an important underpinning of modern cosmology. Reproducing it is fundamental to viable progenitor/explosion scenarios. In this talk, I consider the observational properties of the extremes of the relationship: the luminous, slow-declining "91T-like" SNe and the sub-luminous, fast declining "91bg-like" events. Both extremes have long been referred to as "peculiar" (particularly by cosmologists), but I will argue that this is a terminology that should be retired.