Yi Cao
(Caltech)
Fast and Furious: Young Supernovae and Their Progenitors
Observations of supernovae within a few days of explosion provide unique
constraints to the nature of their progenitors. Since 2013, as a part of my
thesis, I used the intermediate Palomar Transient Factory (iPTF) to
systematically study extraordinarily young supernovae. I will first provide
an overview of iPTF survey design, summarize the fast turnaround discovery
pipeline and then outline the rapid response follow-up. The highlights of my
work are as follows: 1) We observed a strong declining UV pulse from a
low-velocity Type Ia supernova which is consistent with the expected radiation
from a supernova slamming into a companion star. This UV pulse strongly
suggests the so-called "single degenerate" channel for Type Ia supernovae.
2) We found a peculiar Type Ia supernova which follows the empirical relation
between peak magnitude, lightcurve shape and maximum color for cosmological
measurement. It also shares observational features with super-Chandrasekhar
events, indicating an ejecta mass exceeding the Chandrasekhar limit. Thus
this object probably arises from the so-called "double-degenerate" channel.
Our observations together support multiple origin channels of
Type Ia supernovae. Additionally, we identified the first progenitor
candidate of a Type Ib supernova in the pre-explosion HST images. Our
multi-wavelength observations of this young Type Ib supernova constrain its
progenitor to be smaller than several solar radii and with strong mass loss.
I will end my talk with prospects for this field with the upcoming Zwicky
Transient Facility.