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Initial Perturbations on Ultra-Small Scales and Primordial Black Holes in the Era of Gravitational-Wave Astronomy

引力波天文学时代超小尺度和原始黑洞的初始扰动

基本信息

批准号：
1820861
负责人：
Yacine Ali-Haimoud
金额：
$ 21万
依托单位：
New York University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-15 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1820861&HistoricalAwards=false
关键词：
Initial Perturbations Ultra Small Scales

项目摘要

This award funds the research activities of Professor Yacine Ali-Haimoud at New York University.After decades of increasingly detailed observations, it is well established that the Universe contains a large amount of unknown matter that interacts little, if at all, with known forms of matter. Understanding the nature of this "dark matter" is one of the major unsolved problems in physics. Primordial black holes (PBH's) are fascinating dark-matter candidates. PBH's could have formed in the infant Universe, before the first stars even existed. Professor Ali-Haimoud aims to develop tests of PBH's by predicting their effect on maps of the early Universe and examining the gravitational waves they would emit, and by comparing these predictions with observations. In addition, he will develop a novel way to study the initial conditions of the Universe by quantifying their impact on certain cosmological phase transitions. As such, this research serves the national interest by promoting the progress of fundamental science in the United States. This research will also have significant broader impacts. Professor Ali-Haimoud will include the results of this research in his graduate and undergraduate physics courses and will also directly engage students in these investigations. In addition, he will develop a course for underserved New York City high-school students on the physics of sailing in which he hopes to foster enthusiasm for physics by drawing parallels between sailing and gravitational waves and black holes. More specifically, the first and main focus of this research is to establish robust limits on the abundance of PBH's of about one to one thousand solar masses through their impact on cosmic microwave background (CMB) anisotropies, and especially their gravitational-wave signals for the Laser Interferometer Gravitational-Wave Observatory (LIGO). Professor Ali-Haimoud will extend his analytic calculations of the merger rate of PBH binaries to realistic mass distributions, estimate the resulting stochastic gravitational-wave background accounting for high eccentricities, and establish through numerical simulation whether PBH binaries formed in the early Universe are significantly affected by non-linear structures. He will also extend his work on CMB limits by estimating the self-consistent luminosity of accreting PBH's, and by studying the nature of accretion (spherical vs. disk-like). The second project involves exploring an entirely new idea: the impact of small-scale baryon perturbations on the global recombination history. This effect can probe the currently unconstrained small-scale baryon isocurvature perturbation. Professor Ali-Haimoud will explore this idea quantitatively by studying perturbed radiative transfer in the Lyman-alpha line during recombination.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.

该奖项资助纽约大学Yacine Ali-Haimoud教授的研究活动。经过几十年越来越详细的观察，我们已经确定，宇宙中含有大量的未知物质，它们与已知形式的物质几乎没有相互作用，如果有的话。了解这种“暗物质”的本质是物理学中尚未解决的主要问题之一。原始黑洞（PBH’s）是令人着迷的暗物质候选者。PBH可能在早期宇宙中形成，甚至在第一批恒星存在之前。Ali-Haimoud教授的目标是通过预测PBH对早期宇宙地图的影响，检查它们可能发射的引力波，并将这些预测与观测结果进行比较，来开发PBH的测试。此外，他将开发一种新的方法来研究宇宙的初始条件，通过量化它们对某些宇宙相变的影响。因此，这项研究通过促进美国基础科学的进步来服务于国家利益。这项研究还将产生更广泛的重大影响。Ali-Haimoud教授将把这项研究的结果纳入他的研究生和本科生物理课程，并将直接让学生参与这些研究。此外，他还将为缺乏教育的纽约市高中生开设一门帆船物理学课程，他希望通过将帆船运动与引力波和黑洞进行比较，来培养他们对物理学的热情。更具体地说，本研究的首要重点是通过PBH对宇宙微波背景（CMB）各向异性的影响，特别是对激光干涉仪引力波天文台（LIGO）的引力波信号的影响，建立大约1到1000个太阳质量的PBH丰度的可靠限制。Ali-Haimoud教授将把他对PBH双星合并率的解析计算扩展到现实的质量分布，估计由此产生的高偏心率的随机引力波背景，并通过数值模拟确定早期宇宙中形成的PBH双星是否受到非线性结构的显著影响。他还将通过估计吸积PBH的自洽光度，以及研究吸积的性质（球形与盘状）来扩展他在CMB极限方面的工作。第二个项目涉及探索一个全新的想法：小尺度重子扰动对全球重组历史的影响。这种效应可以探测到目前无约束的小尺度重子等曲率扰动。Ali-Haimoud教授将通过研究重组过程中Lyman-alpha线的扰动辐射传递来定量地探索这一想法。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。