RUI: WoU-MMA: Multi-Messenger Astronomy and Astrophysics with Gravitational-Wave Data

RUI：WoU-MMA：利用引力波数据的多信使天文学和天体物理学

• 批准号: 2110576
• 负责人: Shaon Ghosh
• 金额: $ 15万
• 依托单位: Montclair State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-15 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2110576&HistoricalAwards=false
• 关键词: RUI; WoU; MMA; Multi; Messenger

More than a hundred years ago Albert Einstein in his general theory of relativity predicted the existence of gravitational waves, ripples in the fabric of spacetime that propagate at the speed of light. These waves are generated by some of the most violent events in the universe, like colliding neutron stars and coalescing black holes. When two neutron stars collide the matter inside the neutron star is expelled out. Outside the extreme environment of the neutron star this matter is unstable and decays rapidly, radiating electromagnetic waves that can be detected billions of lightyears away. These electromagnetic events are called Kilonova. A kilonova however is a very rare event (roughly happening once per million years) in a Milky Way like galaxy. Thus, to have a reasonable chance of detecting these events we need to be able to see deep into the universe, giving us access to a large number of galaxies. This also means that most of the kilonova that we will be detecting are going to be at the farthest distances that we can reach, and hence will be very faintly observable from Earth. To make matters more complicated, these events also rapidly fade away. Thus, it is very important that observers are looking at the right part of the sky immediately after two neutron stars have collided. Detection of gravitational waves from a coalescing neutron star will allow us to localize the region of the sky and calculate the probability of having an electromagnetic emission as a result of these collisions. The PI will develop components of a low-latency gravitational wave alert infrastructure that will use gravitational wave detections to facilitate follow-up observations using telescopes around the world and in space. Secondly, the structure of neutron stars itself continues to remain a mystery in physics. This is primarily because there is no way of emulating the extreme environment akin to the interior of a neutron star in a laboratory. Gravitational waves reveal to us important clues about the matter inside the neutron star that can be used to improve out understanding of their structure. The PI will develop a technology that will allow combining gravitational wave data from multiple binary neutron star coalescence events to compare different theoretical models of neutron star matter. The tool will also help the user to compare custom-made models, allowing exploratory studies on models that are not currently predicted by any theory. The results of both these projects will provide tools and data to physicists, astronomers, and astrophysicists in the US and around the world to pursue further scientific investigations. The PI, who is a professor at a regional public university, will mentor undergraduate students at his institution, giving them the opportunity to work on large volumes of data and learn statistical techniques. This will prepare them as future scientists, engineers, and/or data analysts in an increasingly data driven world. The PI will engage with the broader public through lectures, outreach exhibits, teacher training programs to ensure dissemination of knowledge acquired.The LIGO-Virgo collaboration has organized three observing runs which have led to more than fifty detection of gravitational waves from binaries of orbiting neutron stars and black holes. With scheduled improvements in the detectors we expect to see as many as ten times more astrophysical events in the next LIGO run (O4). Furthermore, in O4 we expect to see the inauguration of the fourth gravitational wave detector, KAGRA in Japan. Thus, an increased sensitivity of the detectors, greater duty cycle and improved sky-sensitivity due to an extra detector in the network are going to greatly increase the rate detection. The infrastructure currently in place from the last observing run is inadequate to meet this high throughput of events. The PI commits to deliver a low-latency alert infrastructure that is capable of handling the expected increase of low-latency triggers from the gravitational wave detectors. This infrastructure will address the key issues of the last observing run that resulted in delays in the alert process. The PI proposes to develop cyberinfrastructure to process alert streams and provide source-classification and source-properties information to the public in less 10 seconds after detection. Secondly, the PI will also develop a technology that will rapidly combine information from multiple gravitational wave observations of coalescing neutron star binaries to improve the understanding of the internal structure neutron stars. This tool will leverages upon a single parameter estimation study that is agnostic about the nature of the matter inside the neutron star (equation of state). It will then employ a series of valid approximations, to reduce the computational requirement enabling the rapid calculation of the ratio of the evidences (Bayes-factor) of any two models of the neutron star equation of state. This method can then be extended to the computation of joint Bayes-factors of multiple events, giving us a holistic picture about the neutron star equation of state.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.

一百多年前，阿尔伯特·爱因斯坦在他的广义相对论中预言了引力波的存在，引力波是时空结构中以光速传播的涟漪。这些波是由宇宙中一些最剧烈的事件产生的，比如中子星碰撞和黑洞合并。当两颗中子星相撞时，中子星星内部的物质被驱逐出去。在中子星星的极端环境之外，这种物质是不稳定的，并且迅速衰变，辐射出的电磁波可以在数十亿光年之外被探测到。这些电磁事件被称为Kilonova。然而，千诺瓦是一个非常罕见的事件（大约每百万年发生一次）在银河系这样的星系。因此，为了有合理的机会探测到这些事件，我们需要能够看到宇宙深处，让我们能够进入大量的星系。这也意味着我们将要探测到的大部分千诺瓦将位于我们所能到达的最远距离，因此从地球上可以非常微弱地观测到。让事情变得更加复杂的是，这些事件也迅速消失。因此，在两颗中子星相撞后，观测者立即观察天空的正确部分是非常重要的。探测到来自合并中子星星的引力波将使我们能够定位天空的区域，并计算这些碰撞产生电磁辐射的概率。PI将开发低延迟引力波警报基础设施的组件，该基础设施将使用引力波探测来促进使用世界各地和太空望远镜的后续观测。其次，中子星本身的结构在物理学上仍然是一个谜。这主要是因为没有办法在实验室中模拟类似于中子星星内部的极端环境。引力波向我们揭示了关于中子星星内部物质的重要线索，这些线索可以用来提高我们对它们结构的理解。PI将开发一种技术，该技术将允许结合来自多个双中子星星合并事件的引力波数据，以比较中子星星物质的不同理论模型。该工具还将帮助用户比较定制模型，允许对目前未被任何理论预测的模型进行探索性研究。这两个项目的成果将为美国和世界各地的物理学家、天文学家和天体物理学家提供工具和数据，以进行进一步的科学研究。PI是一所地区公立大学的教授，他将指导他所在机构的本科生，让他们有机会处理大量数据并学习统计技术。这将使他们在日益数据驱动的世界中成为未来的科学家，工程师和/或数据分析师。PI将通过讲座，外展展览，教师培训计划与更广泛的公众接触，以确保所获得的知识的传播。LIGO-Virgo合作组织了三次观测运行，导致超过50个来自轨道中子星和黑洞双星的引力波探测。随着探测器的预定改进，我们预计在下一次LIGO运行（O 4）中将看到多达十倍的天体物理事件。此外，在O 4中，我们预计将看到第四个引力波探测器KAGRA在日本的落成典礼。因此，由于网络中的额外检测器而增加的检测器灵敏度、更大的占空比和改进的天空灵敏度将大大提高检测速率。从上一次观测运行开始，目前的基础设施不足以满足事件的高吞吐量。PI承诺提供一个低延迟警报基础设施，能够处理来自引力波探测器的低延迟触发的预期增加。这一基础设施将解决上一次观测运行中导致警报过程延迟的关键问题。PI建议开发网络基础设施，以处理警报流，并在检测后10秒内向公众提供源分类和源属性信息。其次，PI还将开发一种技术，该技术将快速联合收割机结合来自合并中子星星双星的多个引力波观测的信息，以提高对中子星内部结构的理解。这个工具将利用一个单一的参数估计研究，这是不可知的性质的物质内部的中子星星（状态方程）。然后，它将采用一系列有效的近似，以减少计算的要求，使任何两个模型的中子星星状态方程的证据（贝叶斯因子）的比率的快速计算。这种方法可以扩展到多个事件的联合贝叶斯因子的计算，给我们一个关于中子星星状态方程的整体画面。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

项目成果

Rapid model comparison of equations of state from gravitational wave observation of binary neutron star coalescences

• DOI: 10.1103/physrevd.104.083003
• 发表时间: 2021-04
• 期刊: Physical Review D
• 影响因子: 5
• 作者: Shaon Ghosh;Xiaoshu Liu;J. Creighton;I. M. Hernandez;W. Kastaun;G. Pratten

Rapid hierarchical inference of neutron star equation of state from multiple gravitational wave observations of binary neutron star coalescences

从双中子星聚结的多次引力波观测中快速分层推断中子星状态方程

• DOI: 10.1103/physrevd.107.043035
• 发表时间: 2023
• 期刊: Physical Review D
• 影响因子: 5
• 作者: Ray, Anarya;Camilo, Michael;Creighton, Jolien;Ghosh, Shaon;Morisaki, Soichiro
• 通讯作者: Morisaki, Soichiro