ATCA observations of the MACS-Planck Radio Halo Cluster Project
I. New detection of a radio halo in PLCK G285.0-23.7 ⋆
1 Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Bvd de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
2 School of Chemical & Physical Sciences, Victoria University of Wellington, PO Box 600, 6140 Wellington, New Zealand
3 INAF−Osservatorio di Radioastronomia, via P. Gobetti 101, 40129 Bologna, Italy
4 Department of Physics and Astronomy, UniBO, via Ranzani 1, 40127 Bologna, Italy
5 Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 Leiden, The Netherlands
6 Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
7 Institut d’Astrophysique Spatiale, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Bât. 121, 91405 Orsay Cedex, France
Received: 25 April 2016
Accepted: 17 June 2016
Aims. We investigate the possible presence of diffuse radio emission in the intermediate redshift, massive cluster PLCK G285.0-23.7 (z = 0.39, M500 = 8.39 × 1014M⊙).
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.
Key words: galaxies: clusters: general / galaxies: clusters: individual: PLCK G285.0-23.7 / radio continuum: galaxies / galaxies: clusters: intracluster medium / radiation mechanisms: non-thermal
The reduced image (FITS file) is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A116
© ESO, 2016