Collaborative Research: PM: RUI: Searches for Ultralight Bosonic Dark Matter with Atomic Magnetometer Networks

天体物理观测表明，宇宙中高达85%的物质与构成我们日常世界的物质不同。所谓的暗物质是什么？这个问题的答案仍然是个谜。一种可能性是暗物质可能是以大尺度结构的形式存在（许多倍于地球的大小），与普通物质弱耦合。另一种可能性是暗物质可能以不同强度的波的形式存在。如果这样的结构或波穿过地球，它们可能与原子相互作用，产生类似于磁场的效应。这笔拨款将为三所本科院校提供支持，即加州州立大学-东湾、奥伯林学院和巴克内尔大学，与一个国际团队合作寻找这种暗物质。全球光学磁力仪网络（GNOME）是一个由世界各地的15个机构组成的合作项目，这些机构已经建造了能够检测暗物质信号的精密原子磁力仪。来自磁强计网络的数据被分析，以寻找相关性，这些相关性将表明地球通过暗物质结构或波的通道。主要研究人员将与本科生合作，为网络开发更灵敏的探测器，分析网络数据，并与全球合作探测暗物质。这些测量将深入了解暗物质的可能形式，并更好地了解我们宇宙的构成，同时为下一代科学家提供重要的研究经验和培训。暗物质的一个很好的候选者是超轻玻色子，如轴子、类轴子粒子（ALP）或质量非常低（远小于1 eV）的隐藏光子。超轻玻色子场可以形成稳定的宏观配置，例如拓扑缺陷或玻色子星，例如由于自相互作用。即使没有这种效应，玻色子暗物质场也表现出随机波动。此外，灾难性的天体物理事件可能会产生奇异的超轻玻色子场的强烈爆发。在任何一种情况下，当超轻玻色子场穿过地球时，地面探测器将见证瞬态事件，而不是沐浴在均匀的通量中。全球光学磁力计网络（GNOME）是一个由十几个时间同步光学原子磁力计组成的网络，用于搜索对瞬态信号敏感的相关信号，这些信号是由于与超轻玻色子场的自旋相关相互作用而产生的。GNOME磁力计具有多层磁屏蔽，可减少外部磁噪声，但允许大多数类型的玻色子暗物质穿透而不损失灵敏度。一个突出的例外是隐藏的光子，其信号可以通过屏蔽显着减少。为了寻找隐藏的光子暗物质，主要研究人员和本科生研究人员将构建一个新的无屏蔽磁力计网络，该网络基于GNOME架构，位于磁安静环境中。拟议的实验将探索广泛的未开发的参数空间描述超轻玻色子fields.This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。

Astrophysical observations indicate that up to 85% of the matter in the universe is unlike the matter that makes up our everyday world. What is this so-called dark matter? The answer to that question remains a mystery. One possibility is that dark matter could be in the form of large-scale structures (many times the size of the Earth) that couple weakly to ordinary matter. Another possibility is that the dark matter could be in the form of waves of varying intensity. If such structures or waves were to pass through the Earth they might interact with atoms and cause effects similar to those from a magnetic field. This grant will provide support for three undergraduate institutions, California State University – East Bay, Oberlin College, and Bucknell University, to work with an international team to search for dark matter of this kind. The Global Network of Optical Magnetometers to search for Exotic physics (GNOME) is a collaboration of fifteen institutions throughout the world that have constructed precision atomic magnetometers that are capable of detecting such signals from dark matter. The data from the magnetometer network are analyzed to look for correlations that would indicate the Earth’s passage through dark matter structures or waves. The principal investigators will work with undergraduate students to develop more sensitive detectors for the network, analyze the network data, and work with the worldwide collaboration to detect dark matter. These measurements will give insight into the possible forms of dark matter and lead to a better understanding of the makeup of our universe while providing crucial research experience and training for the next generation of scientists. A well-motivated candidate for dark matter consists of ultralight bosons such as axions, axion-like particles (ALPs), or hidden photons with very low mass (much less than 1 eV). Ultralight bosonic fields can form stable, macroscopic configurations such as topological defects or boson stars due to, for example, self-interactions. Even in the absence of such effects, bosonic dark matter fields exhibit stochastic fluctuations. Additionally, it is possible that cataclysmic astrophysical events could produce intense bursts of exotic ultralight bosonic fields. In any of these scenarios, instead of being bathed in a uniform flux, terrestrial detectors will witness transient events when ultralight bosonic fields pass through Earth. The Global Network of Optical Magnetometers to search for Exotic physics (GNOME) is a network of more than a dozen time-synchronized optical atomic magnetometers searching for correlated signals that is sensitive to transient signals due to spin-dependent interactions with ultralight bosonic fields. GNOME magnetometers have multi-layer magnetic shields that reduce external magnetic noise but allow most types of bosonic dark matter to penetrate within with no loss of sensitivity. A prominent exception is hidden photons, whose signals can be significantly reduced by shielding. To search for hidden photon dark matter, the principal investigators and undergraduate researchers will construct a new network of unshielded magnetometers, based on the GNOME architecture, located in magnetically quiet environments. The proposed experiments will probe a wide range of unexplored parameter space describing ultralight bosonic fields.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.