Publications of the Astronomical Society of Japan, vol. 71, no. 4, pp. 74

Authors:

  • Naoki Yasuda
  • Masaomi Tanaka
  • Nozomu Tominaga
  • Ji-an Jiang
  • Takashi J. Moriya
  • Tomoki Morokuma
  • Nao Suzuki
  • Ichiro Takahashi
  • Masaki S. Yamaguchi
  • Keiichi Maeda
  • Masao Sako
  • Shiro Ikeda
  • Akisato Kimura
  • Mikio Morii
  • Naonori Ueda
  • Naoki Yoshida
  • Chien-Hsiu Lee
  • Sherry H. Suyu
  • Yutaka Komiyama
  • Nicolas Regnault
  • David Rubin

URL:

Abstract:

We present an overview of a deep transient survey of the COSMOS field with the Subaru Hyper Suprime-Cam (HSC). The survey was performed for the 1.77 deg$^2$ ultra-deep layer and 5.78 deg$^2$ deep layer in the Subaru Strategic Program over six- and four-month periods from 2016 to 2017, respectively. The ultra-deep layer reaches a median depth per epoch of 26.4, 26.3, 26.0, 25.6, and 24.6 mag in $g$, $r$, $i$, $z$, and $y$ bands, respectively; the deep layer is $\sim$0.6 mag shallower. In total, 1824 supernova candidates were identified. Based on light-curve fitting and derived light-curve shape parameter, we classified 433 objects as Type Ia supernovae (SNe); among these candidates, 129 objects have spectroscopic or COSMOS2015 photometric redshifts and 58 objects are located at $z > 1$. Our unique data set doubles the number of Type Ia SNe at $z > 1$ and enables various time-domain analyses of Type II SNe, high-redshift superluminous SNe, variable stars, and active galactic nuclei.