Panning for gold, but finding helium: Discovery of the ultra-stripped supernova SN 2019wxt from gravitational-wave follow-up observations
Panning for gold, but finding helium: Discovery of the ultra-stripped supernova SN 2019wxt from gravitational-wave follow-up observations
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淘金却发现氦：通过引力波后续观测发现超剥离超新星 SN 2019wxt
DOI：
10.1051/0004-6361/202244751
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发表时间：
2023
影响因子：
6.5
通讯作者：
Agudo I
中科院分区：
文献类型：
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作者：
Agudo I
我们展示了在 S191213g 的密集后续活动中发现的瞬变的多波长观测结果，S191213g 是 LIGO-Virgo Collaboration 报告的引力波 (GW) 事件，在低延迟搜索中可能是双中子星合并。这次搜索产生了 SN 2019wxt，这是一个星系中的年轻瞬变，其天空位置（在 80% GW 轮廓中）和距离（~150 Mpc）似乎与 GW 事件的定位不确定性兼容。最初，瞬变的年龄受到严格限制，其峰值震级相对较弱（Mi∼ −16.7 mag），以及每 5 天 ∼1 mag 的热能带衰减率似乎暗示着一次紧凑的双星合并。然而，SN 2019wxt在光谱上类似于Ib型超新星，对光学近红外演化的分析很快得出结论：虽然它不能与S191213g联系在一起，但它仍然代表了恒星演化的极端结果。通过对光变曲线进行建模，我们估计喷射物质量仅为∼0.1M⊙，其中 56Ni 占其中的∼20%。我们基本上能够重现其光谱演变，其成分主要是氦和氧，并含有微量的钙。我们考虑了可能产生 SN 2019wxt 所观察到的特性的各种祖通道，并得出结论，双星系统中的超剥离起源是最可能的解释。在发现后不久，将引力波事件的真实电磁对应物与 SN 2019wxt 等瞬变现象分开是具有挑战性的：为了描述这种污染程度，我们估计了体积速率密度与 SN 2019wxt 相当的事件发生率，并发现在 O4 警报的典型引力波定位区域内，每周大约会发生一次这样的事件，光度距离为 500 Mpc，超过这个光度距离，它将变得比 SN 2019wxt 更暗。当前电磁后续活动的典型深度。
We present the results from multi-wavelength observations of a transient discovered during an intensive follow-up campaign of S191213g, a gravitational wave (GW) event reported by the LIGO-Virgo Collaboration as a possible binary neutron star merger in a low latency search. This search yielded SN 2019wxt, a young transient in a galaxy whose sky position (in the 80% GW contour) and distance (∼150 Mpc) were plausibly compatible with the localisation uncertainty of the GW event. Initially, the transient’s tightly constrained age, its relatively faint peak magnitude (Mi∼ −16.7 mag), and ther-band decline rate of ∼1 mag per 5 days appeared suggestive of a compact binary merger. However, SN 2019wxt spectroscopically resembled a type Ib supernova, and analysis of the optical-near-infrared evolution rapidly led to the conclusion that while it could not be associated with S191213g, it nevertheless represented an extreme outcome of stellar evolution. By modelling the light curve, we estimated an ejecta mass of only ∼0.1M⊙, with56Ni comprising ∼20% of this. We were broadly able to reproduce its spectral evolution with a composition dominated by helium and oxygen, with trace amounts of calcium. We considered various progenitor channels that could give rise to the observed properties of SN 2019wxt and concluded that an ultra-stripped origin in a binary system is the most likely explanation. Disentangling genuine electromagnetic counterparts to GW events from transients such as SN 2019wxt soon after discovery is challenging: in a bid to characterise this level of contamination, we estimated the rate of events with a volumetric rate density comparable to that of SN 2019wxt and found that around one such event per week can occur within the typical GW localisation area of O4 alerts out to a luminosity distance of 500 Mpc, beyond which it would become fainter than the typical depth of current electromagnetic follow-up campaigns.