Centre for Astrophysics Research, School of Physics, Engineering and Computer Science, University of Hertfordshire, Hatfield, UK.
Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA, USA.
Nature. 2023 Sep;621(7979):483-486. doi: 10.1038/s41586-023-06346-4. Epub 2023 Sep 6.
Magnetic fields are fundamental to the evolution of galaxies, playing a key role in the astrophysics of the interstellar medium and star formation. Large-scale ordered magnetic fields have been mapped in the Milky Way and nearby galaxies, but it is not known how early in the Universe such structures formed. Here we report the detection of linearly polarized thermal emission from dust grains in a strongly lensed, intrinsically luminous galaxy that is forming stars at a rate more than 1,000 times that of the Milky Way at redshift 2.6, within 2.5 Gyr of the Big Bang. The polarized emission arises from the alignment of dust grains with the local magnetic field. The median polarization fraction is of the order of 1%, similar to nearby spiral galaxies. Our observations support the presence of a 5-kiloparsec-scale ordered magnetic field with a strength of around 500 μG or lower, oriented parallel to the molecular gas disk. This confirms that such structures can be rapidly formed in galaxies, early in cosmic history.
磁场对星系的演化至关重要，在星际介质和恒星形成的天体物理中起着关键作用。已经在银河系和附近的星系中绘制出了大尺度有序磁场，但尚不清楚这种结构在宇宙早期是如何形成的。在这里，我们报告了在一个强烈的引力透镜作用下、具有内在光度的星系中尘埃颗粒的线性偏振热辐射的探测，该星系在大爆炸后 2.5 亿年内，以比银河系高 1000 多倍的速率形成恒星。偏振发射源于尘埃颗粒与局部磁场的对齐。中值偏振分数约为 1%，与附近的螺旋星系相似。我们的观测结果支持存在一个 5 千帕尺度的有序磁场，其强度约为 500 μG 或更低，与分子气体盘平行。这证实了这样的结构可以在星系中迅速形成，在宇宙历史的早期。
