标题： 超新星持续时间超过一年的速率限制来自Subaru/Hyper Suprime-Cam 显示英文标题

标题： Constraints on the rate of supernovae lasting for more than a year from Subaru/Hyper Suprime-Cam

摘要： 一些超新星，如对不稳定超新星，预计在观测者框架中的持续时间超过一年。 为了限制持续时间超过一年的超新星的速率，我们使用8.2米 Subaru 望远镜上的 Hyper Suprime-Cam (HSC) 进行了长期深度暂现天体调查。 HSC 是一个宽视场（1.75 平方度视场）的相机，可以高效地进行暂现天体调查。 我们使用 g、r、i 和 z 波段滤光片对相同的 1.75 平方度视场进行了重复观测，典型的深度为 26 等，持续 4 个季节（从 2016 年底到 2020 年初）。 利用这些数据，我们搜索了持续时间超过一年的暂现天体。 在连续两个季节中检测到了两个超新星，在连续三个季节中检测到了一个超新星，但在所有四个季节的搜索中没有发现持续时间超过四个季节的暂现天体。 在典型极限星等为 26 等的情况下，持续时间超过一年的超新星的发现率被限制为 1.4^{+1.3}_{-0.7}（统计）^{+0.2}_{-0.3}（系统） 事件每平方度每年。 我们发现的所有持续时间较长的超新星很可能是 IIn 型超新星，我们的结果表明大约 40% 的 IIn 型超新星具有长时间的光变曲线。 没有发现持续时间超过一年的可能的对不稳定超新星候选体。 通过将调查结果与调查模拟进行比较，我们限制了明亮的对不稳定超新星的速率在红移 z ~ 3 以内最多为 100 Gpc-3 年-1，这相当于核心坍缩超新星速率的 0.01 - 0.1%。 显示英文摘要

摘要： Some supernovae such as pair-instability supernovae are predicted to have the duration of more than a year in the observer frame. To constrain the rates of supernovae lasting for more than a year, we conducted a long-term deep transient survey using Hyper Suprime-Cam (HSC) on the 8.2m Subaru telescope. HSC is a wide-field (a 1.75 deg2 field-of-view) camera and it can efficiently conduct transient surveys. We observed the same 1.75 deg2 field repeatedly using the g, r, i, and z band filters with the typical depth of 26 mag for 4 seasons (from late 2016 to early 2020). Using these data, we searched for transients lasting for more than a year. Two supernovae were detected in 2 continuous seasons, one supernova was detected in 3 continuous seasons, but no transients lasted for all 4 seasons searched. The discovery rate of supernovae lasting for more than a year with the typical limiting magnitudes of 26 mag is constrained to be 1.4^{+1.3}_{-0.7}(stat.)^{+0.2}_{-0.3}(sys.) events deg-2 yr-1. All the long-lasting supernovae we found are likely Type IIn supernovae and our results indicate that about 40% of Type IIn supernovae have long-lasting light curves. No plausible pair-instability supernova candidates lasting for more than a year are discovered. By comparing the survey results and survey simulations, we constrain the luminous pair-instability supernova rate up to z ~ 3 should be of the order of 100 Gpc-3 yr-1 at most, which is 0.01 - 0.1 per cent of the core-collapse supernova rate.