A rotating cosmic string loop has detached from its parent string. In the picture, the loop has undergone a few rotations. The whole process is assumed to take place in the early universe so that strings move through a hot plasma. In such an environment, a cosmic string will create vortices in its wake, just as a stick moving through water. I have depicted equal density surfaces of the plasma to highlight the effect of the string on its environment. These are represented by the tubular structures shown in the picture.
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