A radio structure shaped like a musical treble clef, hidden almost directly behind the plane of the Milky Way, sits inside a galaxy cluster, NASA’s Chandra and the German-Russian eROSITA telescope have shown by spotting its multimillion-degree gas. The cluster is really two clusters that crashed head-on a few hundred million years ago. A team led by Andrea Botteon of Italy’s INAF, publishing in Astronomy & Astrophysics, says an old outburst from a central black hole first filled the region with fast particles that faded, and the collision then squeezed and re-energised them so they shine again in LOFAR radio images. Our take: the clef shape is pure chance, but the physics is a neat two-act story.
2galaxy clusters colliding
few 100 Myrsince the head-on crash
INAFItalian-led study, A&A