Collaborative Proposal: Enhanced Gravitational Wave Search via Simultaneous Advanced LIGO/Virgo and Evryscope Detection

最近，LIGO/Virgo引力波观测站及其相关的电磁（EM）观测站通过引力波（GW）探测到首次双中子星（BNS）并合，开启了多信使天体物理学的新时代。GW170817事件激发了一种新的GW搜索策略，该策略使用同步的全天光学成像测量来提供更高的探测置信度以及源识别/定位。这笔资金将用于先进LIGO/Virgo （aLIGO/Virgo）运行3 （O3）中改进的GW搜索的开发和测试，有可能大幅增加确认的GW探测数量。这将通过利用现有的引力波和光学天文台的投资，在O3期间提供约25%的探测系统数量，并为未来的多信使调查铺平道路，这可能会使探测到的源数量增加四倍，从而显著提高国家利益的科学进展。该研究是多信使天体物理学、广义相对论、数字信号处理和计算的交叉领域，要求青年研究人员对现代天体物理学理论有深入的了解，对引力波仪器有深入的了解，并有机会获得复杂的信号/图像处理算法、计算方法、大数据集操作和高性能计算的第一手经验。本文提出的新型GW搜索是基于aLIGO/Virgo亚阈值触发器与使用Evryscope技术的同步光学成像相结合。每台望远镜以2分钟的节奏同时拍摄整个可观测的夜空。然后，科学家们可以在aLIGO/Virgo误差区域中只选择那些出现在与GW候选者相同的2分钟窗口内的光学瞬变事件，从而将仅GW的误报概率降低到20,000倍以上。任何夜间GW活动。这可以提高边际GW事件的检测置信度，从而提高GW的检测量。GW1708187的光学对应体可以被当前的Evryscope探测到D ~260 Mpc，未来的Evryscope系统可以探测到350 Mpc以上的距离。分析表明，未来的evryscope型探测器网络将使探测到的GW事件数量比仅探测GW事件的数量增加2-4倍。这样一个未来的网络将特别有利于GW源人口研究和GW事件的宇宙学应用。这种方法还将覆盖光学光曲线中最亮的部分，并对所有这些事件进行弧秒级定位，这将极大地改善整个社区的EM后续响应，从而改善解释GW事件含义的天体物理学背景。本文提出的工作是在aLIGO/Virgo O3中进行亚阈值GW搜索，使用Evryscope南北设备同时进行光学覆盖。基于GW170817的GW特性、光学对应以及本文的分析，这样的搜索可以使O3中确认的BNS合并的探测数量增加~25%。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The recent gravitational wave (GW) detection of the first binary neutron star (BNS) merger by the LIGO/Virgo gravitational wave observatories and its associated electromagnetic (EM) counterparts has ushered in a new era of multi-messenger astrophysics. The GW170817 event has inspired a new GW search strategy using simultaneous all-sky optical imaging measurements to provide improved detection confidence as well as source identification/localization. This grant will fund the development and testing of this improved GW search in Advanced LIGO/Virgo (aLIGO/Virgo) operation run 3 (O3), with the potential to substantially increase the number of confirmed GW detections. This will significantly improve the progress of science in the national interest by leveraging the existing investments in gravitational wave and optical observatories to provide an estimated ~25% enhancement in the number of detected systems during O3, and pave the way for future multi-messenger investigations that could potentially quadruple the number of detected sources. The proposed research is at the intersection of the multi-messenger astrophysics, general relativity, digital signal processing and computing, which require young researchers to develop a deep knowledge of modern astrophysical theories, and understanding of gravitational wave instrumentation, and gives them opportunity to get firsthand experience with sophisticated signal/image-processing algorithms, computational methods, manipulation of large data sets and high performance computing.The novel GW search proposed here is based on combining aLIGO/Virgo sub-threshold triggers with simultaneous optical imaging using the Evryscope technique. Evryscope images the entire observable night-time sky simultaneously with 2-minute cadence. Scientists can then select only those optical transient events in the aLIGO/Virgo error region which appear within the same 2-minute window as the GW candidate - reducing the GW-only false alarm probability by factors larger than 20,000. for any night-time GW events. This enables improved detection confidence for marginal GW events and thus enhanced GW detection volume. GW1708187's optical counterpart could be detected by the current Evryscope out to D ~260 Mpc, and future Evryscope-style systems to distances further than 350 Mpc. Analyses show that a future network of Evryscope-style detectors would enhance the number of GW events detected by a factor of ~2-4 compared to GW-only observations. Such a future network would particularly benefit GW source population studies and cosmological applications of GW events. This approach will also provide coverage of the brightest portion of the optical lightcurve, and arcsecond-level localization for all of these events, which will dramatically improve the EM followup response from the community as a whole, leading to improved astrophysical context for interpreting the implications of the GW event. The proposed work here is to carry out a sub-threshold GW search in aLIGO/Virgo O3, using the Evryscope North and South facilities for simultaneous optical coverage. Based on the properties of GW170817's GW properties, optical counterpart, and analyses presented here, such a search could add an additional ~25% more detections to the number of confirmed BNS mergers in O3.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.