Animation: Odd Radio Circles

Explanation: What do you call a cosmic puzzle that no one expected to see? In this case, Odd Radio Circle s, aka ORCs. ORC-1 typifies the enigmatic five objects, only visible at radio frequencies , that were serendipitously discovered in 2019 using the new Australia n SKA Pathfinder radio array. The final image in the featured video uses 2021 data from the South Africa n MeerKAT array to reveal more detail. The radio data, assigned turquoise colors, are combined with a Dark Energy Survey optical/ IR map. The animated artist's illustration explores just one idea about the ORC s' origins. If two supermassive black holes merge in the center of a galaxy, the associated shockwave s could generate rings of radio radiation. These grow to fill the video frame. The video zooms out so the expansion the ORC can be tracked until it is about a million light-year s across. Fortunately, the up-coming Square Kilometer Array can help test this and other promising scenarios.