Collaborative Research: Disentangling the Cosmic Web with Fast Radio Bursts

多年来，天文学家一直试图了解和观察星系之间的扩散气体，也被称为星系际介质（IGM）或-更通俗地说-宇宙网。 加州大学圣克鲁斯分校（UCSC）和玛丽亚·米切尔天文台（MMO）之间的研究合作将使用最近发现的一种称为快速射电暴（FRB）的短天文事件的精确观测来调查并试图解开宇宙网。 该项目将涉及对100多个定位良好的FRB的光学和红外跟踪观测的获取和分析，这些FRB是使用领先的FRB精确定位实验（ASKAP，realfast和DSA-110）发现的，然后用大口径望远镜进行观测。 使用计划的数据集，天文学家将专注于三项主要活动：（i）获得托管FRB的星系的后续成像和光谱学，（ii）解决本星系群中电离气体的分布，以及（iii）解开宇宙网。 该项目将支持UCSC观测天文学全日制博士生的教育和培训。 与此同时，MMO的桥梁计划将为来自代表性不足社区的研究生提供机会，以建立过渡到博士课程所需的技能（例如编程，统计，观察）。宇宙学尺度（~100 Mpc）的数值模拟现在声称可以捕获精确预测IGM天体物理所需的所有突出物理。这些模拟预测，大约50%的气体是在一个温暖的热电离介质（WHIM），冲击加热期间，其崩溃到大规模的结构。尽管对WHIM进行了几十年的观测研究，但它仍然是宇宙中最难以捉摸的重子库。与此同时，在单个暗物质晕的尺度上（~100 - 1000 kpc），理论家们对其中气体的质量和分布进行了辩论。 该计划将利用一个新的机会，通过对FRB事件的全面观测调查来解开宇宙网络。从上述三项观测活动中产生的三个主要研究领域是：（i）确定FRB红移，并为产生这些神秘现象的祖先提供新的见解;（ii）利用观测到的FRB色散测量进行一系列旨在调查我们银河系和M31的晕气体的实验，同时也寻找假定的本群介质;和（iii）直接测试IGM（及其WHIM）的现代范例，并评估暗物质晕的重子分数作为其质量，形态和环境的函数。 为了支持从FRB观测中获得的超出项目重点的广泛科学，该计划获得的所有数据将通过一个或多个渠道传播给社区。该奖项反映了NSF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。

For many years, astronomers have been trying to understand and observe the diffuse gas between galaxies, also known as the intergalactic medium (IGM) or -- more colloquially -- the cosmic web. A research collaboration between the University of California-Santa Cruz (UCSC) and the Maria Mitchell Observatory (MMO) will use precise observations of a recently discovered type of short astronomical event called fast radio bursts (FRBs) to investigate and attempt to disentangle the cosmic web. This project will involve the acquisition and analysis of optical and infrared follow-up observations of over 100 well-localized FRBs, discovered using the leading FRB experiments for precise localization (ASKAP, realfast, and DSA-110) and then observed with large aperture telescopes. Using the planned dataset, the astronomers will focus on three main activities: (i) obtain follow-up imaging and spectroscopy of the galaxies hosting FRBs, (ii) resolve the distribution of ionized gas in the Local Group of galaxies, and (iii) disentangle the cosmic web. The project will support the education and training of a full-time PhD student at UCSC in observational astronomy. The Bridge program at MMO, meanwhile, will provide postgraduate students from underrepresented communities the opportunity to build the skill set (e.g. programming, statistics, observing) needed to transition into a PhD program. Numerical simulations on cosmological scales (~100 Mpc) now purport to capture all of the salient physics required to accurately predict the astrophysics of the IGM. These simulations predict that about 50% of the gas is in a warm-hot ionized medium (WHIM), shock-heated during its collapse onto large-scale structures. Despite several decades of observational searches for the WHIM, however, it remains the most elusive baryonic reservoir of the universe. Meanwhile, on the scales of individual dark matter halos (~100 -- 1000 kpc), theorists debate on the mass and distribution of gas within them. The program will leverage a new opportunity to disentangle the cosmic web through a comprehensive, observational survey of FRB events. The three main research areas arising from the three observational activities listed above are: (i) establish the FRB redshift and provide new insights into the progenitors that generate these enigmatic phenomena; (ii) use the observed FRB dispersion measures to perform a series of experiments designed to survey the halo gas of our Galaxy and M31, while also searching for the putative Local Group medium; and (iii) directly test the modern paradigm for the IGM (and its WHIM) and assess the baryon fraction of dark matter halos as a function of their mass, morphology, and environment. To support the great breadth of science derived from FRB observations beyond the focus of the project, all of the data obtained with this program will be disseminated to the community through one or more channels.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.