Fast-transient Searches in Real Time with ZTFReST: Identification of Three Optically Discovered Gamma-Ray Burst Afterglows and New Constraints on the Kilonova Rate
Fast-transient Searches in Real Time with ZTFReST: Identification of Three Optically Discovered Gamma-Ray Burst Afterglows and New Constraints on the Kilonova Rate
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DOI：
10.3847/1538-4357/ac0bc7
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发表时间：
2021-09-01
影响因子：
4.9
通讯作者：
Yao, Yuhan
中科院分区：
文献类型：
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作者：
Andreoni, Igor;Coughlin, Michael W.;Yao, Yuhan
发现河外快速瞬变的最常见方法是跟踪伽马射线爆发和引力波触发，这些瞬变在光学系统中几个晚上就会消失。然而，广泛的实地调查有可能发现快速衰落的瞬变，而不依赖于这种外部触发因素。兹维基瞬变设备(ZTF)的体积测量速度使其对像千年星这样微弱和快速衰落的物体非常敏感，千星是双星中子星合并的光学对应物，最高可达200Mpc。我们介绍了一个开源软件基础设施，ZTF实时搜索和触发，ZTFReST，旨在识别ZTF数据中的千新世和快速瞬变。利用ZTF警报流和强制点扩散函数测光相结合的方法，实现了基于测光演化和KONOVA模型的自动候选排序。还实施了后续系统的自动触发，由人在回路中进行监测。在13个月的科学验证中，我们发现了几个独立于任何外部触发的银河系外快速瞬变，包括两个具有震后冷却发射的超新星，两个与伽马射线爆发相关的已知余辉(ZTF20abbiixp，ZTF20abwysqy)，两个已知的没有任何已知伽马射线对应的余辉(ZTF20aajnksq，ZTF21aaeyldq)，以及三个新的快速衰减源(ZTF20abtxwfx，ZTF20aco zryr，ZTF21aagwbjr)，可能与GRB200817A，GRB201103B和GRB210204A有关。然而，我们还没有发现任何看起来像是奇诺瓦的物体。我们将GW170817类konovae的比率限制在R<；900 GPC(-3)Yr(-1)(95%置信度)。像ZTFReST这样的框架可能会成为维拉·鲁宾天文台进行千诺瓦和快速瞬变发现的主要工具。
The most common way to discover extragalactic fast transients, which fade within a few nights in the optical, is via follow-up of gamma-ray burst and gravitational-wave triggers. However, wide-field surveys have the potential to identify rapidly fading transients independently of such external triggers. The volumetric survey speed of the Zwicky Transient Facility (ZTF) makes it sensitive to objects as faint and fast fading as kilonovae, the optical counterparts to binary neutron star mergers, out to almost 200 Mpc. We introduce an open-source software infrastructure, the ZTF REaltime Search and Triggering, ZTFReST, designed to identify kilonovae and fast transients in ZTF data. Using the ZTF alert stream combined with forced point-spread-function photometry, we have implemented automated candidate ranking based on their photometric evolution and fitting to kilonova models. Automated triggering, with a human in the loop for monitoring, of follow-up systems has also been implemented. In 13 months of science validation, we found several extragalactic fast transients independently of any external trigger, including two supernovae with post-shock cooling emission, two known afterglows with an associated gamma-ray burst (ZTF20abbiixp, ZTF20abwysqy), two known afterglows without any known gamma-ray counterpart (ZTF20aajnksq, ZTF21aaeyldq), and three new fast-declining sources (ZTF20abtxwfx, ZTF20acozryr, ZTF21aagwbjr) that are likely associated with GRB200817A, GRB201103B, and GRB210204A. However, we have not found any objects that appear to be kilonovae. We constrain the rate of GW170817-like kilonovae to R < 900 Gpc(-3) yr(-1) (95% confidence). A framework such as ZTFReST could become a prime tool for kilonova and fast-transient discovery with the Vera Rubin Observatory.