The merging galaxy cluster Abell 3266 at low radio frequencies

Abstract

ABSTRACT We present new low-frequency (ν = 88–216 MHz) observations of the complex merging galaxy cluster Abell 3266. These new observations are taken with the Murchison Widefield Array (MWA) in its Phase II ‘extended’, long-baseline configuration, offering the highest resolution low-frequency view of the cluster to date. We report on the detection of four steep spectrum (α ≲ −1 for Sν ∝ να) extended radio sources within the cluster. We confirm the detection of a ∼570 kpc radio relic to the south of the cluster, and a possible bridge of emission connecting the relic to the cluster core. We also detect two new ultra-steep-spectrum (α ≲ −1.7) fossil plasma sources to the north and west of the cluster centre without associated compact radio emission. A previously detected radio galaxy in the cluster is also found to have a spectrally steepening tail with steep-spectrum components highlighted by the MWA. The timeline of the merger and the overall mass of the system are consistent with clusters hosting giant radio haloes, yet we do not detect a radio halo in Abell 3266. After simulating a range of radio haloes at 216 MHz, we place upper limits on the radio luminosity corresponding to ∼7.2 × 1024 W Hz−1 at 150 MHz assuming the expected 500 kpc radius – up to a factor of 5 lower than expected from scaling relations.