Slow-Speed Supernovae from the Palomar Transient Factory: Two Channels

Understand

Since the discovery of the unusual prototype SN 2002cx, the eponymous class of low-velocity, hydrogen-poor supernovae has grown to include at most another two dozen members identified from several heterogeneous surveys, in some cases ambiguously.

• Here we present the results of a systematic study of 1077 hydrogen-poor supernovae discovered by the Palomar Transient Factory, leading to nine new members of this peculiar class.
• Moreover we find there are two distinct subclasses based on their spectroscopic, photometric, and host galaxy properties: The "SN 2002cx-like" supernovae tend to be in later-type or more irregular hosts, have more varied and generally dimmer luminosities, have longer rise times, and lack a Ti II trough when compared to the "SN 2002es-like" supernovae.
• None of our objects show helium, and we counter a previous claim of two such events.