LOFAR VLBI Observations of Coma a - Nearby Laboratory of Massive Galaxy and Black Hole Formation

Black hole-created radio jets frequently interact violently with their host galaxies at z > 2, creating stars. Coma A (3C277.3) is one of few luminous low-redshift radio sources where jet-galaxy interactions deflect the jet and induce star formation - a nearby laboratory of massive galaxy formation. We present the first LOFAR VLBI radio image of Coma A and compare it with VLT/MUSE optical images and Chandra X-ray maps. Remarkable features of the radio emission are clumpiness, multiple filaments and the relation of the radio to the optical and X-ray morphologies. The optical continuum image shows a swarm of galaxies apparently merging with Coma A, similar to high-redshift radio protoclusters. Three optical clumps are probable remnants of a merging galaxy, fragmented by collision with the jet. We suggest that magnetic turbulence in Coma A-type radio-emitting clumps, could trigger radio jets in quiescent black holes and that positive feedback from radio jets could contribute to the structure of the high-redshift cosmic web. A prediction of such a scenario is that the morphologies of high-redshift extended radio sources are oriented preferentially along cosmic web filaments, with important implications for how the first supermassive black holes formed.