Cosmic Strings from Simulation to Observation

该奖项资助了Ken D教授的研究活动。宇宙弦是非常细的物体，甚至是宇宙学长度的基本物体，它可能存在于我们的宇宙中，也可能不存在。宇宙弦的探测将提供一个窗口，让我们了解任何加速器都无法到达的能量下的基础物理学。 对宇宙超弦网络的观测可以证实弦理论的正确性。 除了LIGO和VIRGO天文台最近发现的引力波爆发外，很可能还有一个始终存在的引力波“背景”。 宇宙弦的环是可能对这种背景有贡献的来源之一，而对背景的观测是发现宇宙弦的一个重要途径。 Olum教授将研究宇宙弦环的形状和运动在其生命过程中如何变化，以及这如何影响它们发出的引力波成为这种背景的一部分。 如果引力波背景被发现，这项研究将帮助我们区分它是来自宇宙弦还是其他来源，并确定宇宙弦网络的性质，如果它是背景的来源。 因此，这一方向的研究通过进一步发展美国的基础科学来促进国家利益。 奥伦教授还将让研究生参与他的工作，从而培养未来几代的研究物理学家。 这项工作还将把宇宙的研究与自然基本定律的研究联系起来。更技术性的是，奥伦教授将分析宇宙弦环上的引力反作用，看看反作用如何改变尖点和扭结等特征。 他将模拟宇宙弦环的真实种群，看看它们的形状在反作用下如何演变，并计算由此产生的引力发射光谱，以与观测结果进行比较。 他还将研究各向异性引力波发射时回路获得的速度，即所谓的“火箭效应”。该奖项反映了NSF的法定使命，并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，被认为值得支持。

This award funds research activities of Professor Ken D. Olum in the Tufts Institute of Cosmology at Tufts University.Cosmic strings are microscopically thin or even fundamental objects of cosmological length, which may or may not exist in our universe. Detection of cosmic strings would provide a window into fundamental physics at energies beyond the reach of any accelerator. Observation of a cosmic superstring network could provide a confirmation of the correctness of string theory. In addition to the bursts of gravitational waves that have recently been discovered by the LIGO and VIRGO observatories, there is likely to be a "background" of gravitational waves that is always present. Loops of cosmic strings are one of the sources that may contribute to this background, and observation of the background is an important way in which cosmic strings might be discovered. Professor Olum will study how the shape and motion of cosmic string loops changes during their lives and how this affects their emission of gravitational waves that become part of this background. If and when the gravitational wave background is discovered, this research will help us to distinguish whether it comes from cosmic strings or some other source, and to determine the properties of the cosmic string network if it is the source of the background. As such, research in this direction advances the national interest by further the development of basic sciences in the United States. Professor Olum will also involve graduate students in his work and thereby train future generations of research physicists. This work will also connect studies of the universe with studies of the fundamental laws of nature.More technically, Professor Olum will analyze gravitational back-reaction on cosmic string loops, to see how features such as cusps and kinks are modified by back-reaction. He will simulate realistic populations of cosmic string loops to see how their shapes evolve under back-reaction and compute the resulting gravitational emission spectrum for comparison with observations. He will also study the velocities acquired by loops in reaction to anisotropic gravitational wave emission, the so-called "rocket effect".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.