Domcke Valerie, Garcia-Cely Camilo
Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
Theoretical Physics Department, CERN, 1 Esplanade des Particules, CH-1211 Geneva 23, Switzerland.
Phys Rev Lett. 2021 Jan 15;126(2):021104. doi: 10.1103/PhysRevLett.126.021104.
In the presence of magnetic fields, gravitational waves are converted into photons and vice versa. We demonstrate that this conversion leads to a distortion of the cosmic microwave background (CMB), which can serve as a detector for MHz to GHz gravitational wave sources active before reionization. The measurements of the radio telescope EDGES can be cast as a bound on the gravitational wave amplitude, h_{c}<10^{-21}(10^{-12}) at 78 MHz, for the strongest (weakest) cosmic magnetic fields allowed by current astrophysical and cosmological constraints. Similarly, the results of ARCADE 2 imply h_{c}<10^{-24}(10^{-14}) at 3-30 GHz. For the strongest magnetic fields, these constraints exceed current laboratory constraints by about 7 orders of magnitude. Future advances in 21 cm astronomy may conceivably push these bounds below the sensitivity of cosmological constraints on the total energy density of gravitational waves.
在磁场存在的情况下，引力波会转化为光子，反之亦然。我们证明这种转化会导致宇宙微波背景（CMB）发生畸变，这可以作为一种探测器，用于探测再电离之前活跃的兆赫兹到吉赫兹引力波源。射电望远镜EDGES的测量结果可以表示为在78兆赫兹时，对于当前天体物理学和宇宙学限制所允许的最强（最弱）宇宙磁场，引力波振幅(h_{c}<10^{-21}(10^{-12}))。类似地，ARCADE 2的结果意味着在3 - 30吉赫兹时(h_{c}<10^{-24}(10^{-14}))。对于最强的磁场，这些限制比当前实验室限制超出约7个数量级。21厘米天文学未来的进展可能会将这些界限推到低于宇宙学对引力波总能量密度限制的灵敏度之下。
