LOFAR HBA observations of Perseus

In our 0.3" (0.11kpc) resolution image, we find that the northern extension of the 3C 84 lobe consists of several narrow 1.5-3 kpc parallel strands of emission. In addition, we detect steep-spectrum filaments associated with a previous outburst of the central AGN radio emission filling two known X-ray "ghost" cavities. At 7" resolution (2.6kpc), our images show a complex structured radio mini-halo, with several edges and filaments.

At resolutions of 26" (10kpc) and 80" (29kpc), we discover diffuse radio emission with a 1.1Mpc extent. We classify this emission as a giant radio halo, and its properties are distinct from the inner mini-halo. We also detect two diffuse sources at projected cluster centric radii of 0.7 and 1.0Mpc.

Finally, we observe a 0.9Mpc trail of radio emission from the cluster member galaxy IC 310 that connects it to the giant radio halo. Together with other recent studies of relaxed clusters, our LOFAR observations indicate that cluster-wide radio emission could be (more) common in cool-core clusters. In the case of the Perseus cluster, a past off-axis merger event that preserved the cool core might have generated enough turbulence to produce an extended radio halo observable at low frequencies.