ATCA observations of the MACS-Planck Radio Halo Cluster Project. I. New detection of a radio halo in PLCK G285.0-23.7

Abstract

Aims: We investigate the possible presence of diffuse radio emission in the intermediate redshift, massive cluster PLCK G285.0-23.7 (z = 0.39, M<SUB>500</SUB> = 8.39 × 10<SUP>14</SUP>M<SUB>☉</SUB>). Methods: Our 16 cm-band ATCA observations of PLCK G285.0-23.7 allow us to reach a rms noise level of 11 μJy/beam on the wide-band (1.1-3.1 GHz), full-resolution ( 5 arcsec) image of the cluster, making it one of the deepest ATCA images yet published. We also re-image visibilities at lower resolution in order to achieve a better sensitivity to low-surface-brightness extended radio sources. Results: We detect one of the lowest luminosity radio halos known at z > 0.35, characterised by a slight offset from the well-studied 1.4 GHz radio power vs. cluster mass correlation. Similarly to most known radio-loud clusters (I.e. those hosting diffuse non-thermal sources), PLCK G285.0-23.7 has a disturbed dynamical state. Our analysis reveals a similarly elongated X-ray and radio morphology. While the size of the radio halo in PLCK G285.0-23.7 is smaller than lower redshift radio-loud clusters in the same mass range, it shows a similar correlation with the cluster virial radius, as expected in the framework of hierarchical structure formation. <P />The reduced image (FITS file) is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A116">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A116