Observational constraints on the optical and near-infrared emission from the neutron star–black hole binary merger candidate S190814bv
Observational constraints on the optical and near-infrared emission from the neutron star–black hole binary merger candidate S190814bv
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DOI：
10.1051/0004-6361/202037669
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发表时间：
2020-02
影响因子：
6.5
通讯作者：
K. Ackley;L. Amati;C. Barbieri;F. Bauer;S. Benetti;M. Bernardini;K. Bhirombhakdi;M. Botticella-M.-Bottice
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文献类型：
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作者：
K. Ackley;L. Amati;C. Barbieri;F. Bauer;S. Benetti;M. Bernardini;K. Bhirombhakdi;M. Botticella-M.-Bottice
上下文。引力波天文学已迅速走向成熟，成为现代天体物理学的一个基本观测窗口。已经探测到几十个黑洞（BH）双星的合并，而可能包括中子星（NS）的事件数量仍然有限。2019年8月14日，LIGO和Virgo干涉仪探测到一个标记为S190814bv的高意义事件。对GW数据的初步分析表明，这一事件可能是由BH和NS组成的紧凑双星系统合并造成的。目标。在本文中，我们展示了我们广泛的搜索活动，旨在揭示S190814bv潜在的光学和近红外电磁对应物。我们在数据中没有发现令人信服的电磁对应物。因此，我们使用我们的非检测来限制可能在合并期间和之后由双星产生的假定流出物的性质。方法。由于对S190814bv的三个探测器的观测，并考虑到信号的特征，LIGO和处女座合作组织在低延迟下提供了相对狭窄的定位- 50%（90%）可信区域为5度2(23度2)-尽管距离相对较大，为267±52 Mpc。引力波源的电磁对应物在超大型望远镜合作成员进行了密集的多历元、多仪器观测活动，以确定该事件可能的光学和近红外对应物。此外，ATLAS、GOTO、GRAWITA-VST、Pan-STARRS和VINROUGE项目也对该事件进行了搜索。在本文中，我们描述了这些群体的联合观测活动。结果。我们的观察使我们能够限制任何对等体的存在，并讨论可能由NS-BH合并产生的千新星（KN）的含义，以及未来搜索的策略。我们的宽视场观测的典型深度为r ~ 22，覆盖了大部分预计的天空定位概率（高达99.8%，取决于所考虑的夜晚和过滤器）。K ~ 21)。近红外)。我们在星系目标观测的子集中达到了更深的极限，这些观测覆盖了星系质量加权局域概率的50%。总的来说，我们的观测结果使我们能够排除具有大抛射质量M > 0.1 M⊙的KN，置信度很高（> 90%），并且我们可以在观测的子样本中排除更小的质量。这不利于中子星在合并过程中潮汐式的分裂。结论。尽管这项运动涉及到敏感的仪器，但考虑到S190814bv的距离，我们无法达到足够深的限制，以限制在很大一部分局部概率上与AT 2017gfo光度相当的KN。这表明，未来几百兆秒差距的事件（可能是常见的）将只有具有高灵敏度和大视场的大型设施才能探测到。以星系为目标的观测可以在定位概率的相关部分上以较小的资源投入达到所需的深度，但是为了获得相当完整的覆盖，即使在像这次事件一样好的定位情况下，要定位的星系数量也是很大的。
Context. Gravitational wave (GW) astronomy has rapidly reached maturity, becoming a fundamental observing window for modern astrophysics. The coalescences of a few tens of black hole (BH) binaries have been detected, while the number of events possibly including a neutron star (NS) is still limited to a few. On 2019 August 14, the LIGO and Virgo interferometers detected a high-significance event labelled S190814bv. A preliminary analysis of the GW data suggests that the event was likely due to the merger of a compact binary system formed by a BH and a NS. Aims. In this paper, we present our extensive search campaign aimed at uncovering the potential optical and near infrared electromagnetic counterpart of S190814bv. We found no convincing electromagnetic counterpart in our data. We therefore use our non-detection to place limits on the properties of the putative outflows that could have been produced by the binary during and after the merger. Methods. Thanks to the three-detector observation of S190814bv, and given the characteristics of the signal, the LIGO and Virgo Collaborations delivered a relatively narrow localisation in low latency – a 50% (90%) credible area of 5 deg2 (23 deg2) – despite the relatively large distance of 267 ± 52 Mpc. ElectromagNetic counterparts of GRAvitational wave sources at the VEry Large Telescope collaboration members carried out an intensive multi-epoch, multi-instrument observational campaign to identify the possible optical and near infrared counterpart of the event. In addition, the ATLAS, GOTO, GRAWITA-VST, Pan-STARRS, and VINROUGE projects also carried out a search on this event. In this paper, we describe the combined observational campaign of these groups. Results. Our observations allow us to place limits on the presence of any counterpart and discuss the implications for the kilonova (KN), which was possibly generated by this NS–BH merger, and for the strategy of future searches. The typical depth of our wide-field observations, which cover most of the projected sky localisation probability (up to 99.8%, depending on the night and filter considered), is r ∼ 22 (resp. K ∼ 21) in the optical (resp. near infrared). We reach deeper limits in a subset of our galaxy-targeted observations, which cover a total ∼50% of the galaxy-mass-weighted localisation probability. Altogether, our observations allow us to exclude a KN with large ejecta mass M ≳ 0.1 M⊙ to a high (> 90%) confidence, and we can exclude much smaller masses in a sub-sample of our observations. This disfavours the tidal disruption of the neutron star during the merger. Conclusions. Despite the sensitive instruments involved in the campaign, given the distance of S190814bv, we could not reach sufficiently deep limits to constrain a KN comparable in luminosity to AT 2017gfo on a large fraction of the localisation probability. This suggests that future (likely common) events at a few hundred megaparsecs will be detected only by large facilities with both a high sensitivity and large field of view. Galaxy-targeted observations can reach the needed depth over a relevant portion of the localisation probability with a smaller investment of resources, but the number of galaxies to be targeted in order to get a fairly complete coverage is large, even in the case of a localisation as good as that of this event.