Skip to main content
eScholarship
Open Access Publications from the University of California

UC Berkeley

UC Berkeley Previously Published Works bannerUC Berkeley

ZTF Early Observations of Type Ia Supernovae. II. First Light, the Initial Rise, and Time to Reach Maximum Brightness

  • Author(s): Miller, AA
  • Yao, Y
  • Bulla, M
  • Pankow, C
  • Bellm, EC
  • Cenko, SB
  • Dekany, R
  • Fremling, C
  • Graham, MJ
  • Kupfer, T
  • Laher, RR
  • Mahabal, AA
  • Masci, FJ
  • Nugent, PE
  • Riddle, R
  • Rusholme, B
  • Smith, RM
  • Shupe, DL
  • Roestel, JV
  • Kulkarni, SR
  • et al.

Published Web Location

https://arxiv.org/pdf/2001.00598
No data is associated with this publication.
Abstract

While it is clear that Type Ia supernovae (SNe) are the result of thermonuclear explosions in C/O white dwarfs (WDs), a great deal remains uncertain about the binary companion that facilitates the explosive disruption of the WD. Here, we present a comprehensive analysis of a large, unique data set of 127 SNe Ia with exquisite coverage by the Zwicky Transient Facility (ZTF). High-cadence (six observations per night) ZTF observations allow us to measure the SN rise time and examine its initial evolution. We develop a Bayesian framework to model the early rise as a power law in time, which enables the inclusion of priors in our model. For a volume-limited subset of normal SNe Ia, we find that the mean power-law index is consistent with 2 in the r ZTF-band (α r=2.01± 0.02), as expected in the expanding fireball model. There are, however, individual SNe that are clearly inconsistent with α r=2. We estimate a mean rise time of 18.9 days (with a range extending from ∼15 to 22 days), though this is subject to the adopted prior. We identify an important, previously unknown, bias whereby the rise times for higher-redshift SNe within a flux-limited survey are systematically underestimated. This effect can be partially alleviated if the power-law index is fixed to α = 2, in which case we estimate a mean rise time of 21.7 days (with a range from ∼18 to 23 days). The sample includes a handful of rare and peculiar SNe Ia. Finally, we conclude with a discussion of lessons learned from the ZTF sample that can eventually be applied to observations from the Vera C. Rubin Observatory.

Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.

Item not freely available? Link broken?
Report a problem accessing this item