2020/07/29 by Stefan W. Duchesne, S. W. Duchesne, M. Johnston‐Hollitt +11 · 1 voice · 1 citation
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Cluster (spacecraft) #Computer science #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Giant Metrewave Radio Telescope #LOFAR #Physics #Radio Astronomy Observations and Technology #Radio galaxy #Radio spectrum #Radio telescope #Redshift #Source counts #Spectral index #Spectral line #astro-ph.GA #astro-ph.IM
paper · pdf · doi:10.48550/arxiv.2007.15199
17 pages, 16 figures, accepted for publication in Publications of the Astronomical Society of Australia (PASA)
arxiv created 2020/07/30 · arxiv published 2020/07/30 · arxiv updated 2020/07/31
Diffuse, non-thermal emission in galaxy clusters is increasingly being\ndetected in low-frequency radio surveys and images. We present a new diffuse,\nsteep-spectrum, non-thermal radio source within the cluster Abell 1127 found in\nsurvey data from the Murchison Widefield Array (MWA). We perform follow-up\nobservations with the 'extended' configuration MWA Phase II with improved\nresolution to better resolve the source and measure its low-frequency spectral\nproperties. We use archival Very Large Array S-band data to remove the discrete\nsource contribution from the MWA data, and from a power law model fit we find a\nspectral index of -1.83\±0.29 broadly consistent with relic-type sources.\nThe source is revealed by the Giant Metrewave Radio Telescope (GMRT) at 150 MHz\nto have an elongated morphology, with a projected linear size of 850 kpc as\nmeasured in the MWA data. Using Chandra observations we derive morphological\nestimators and confirm quantitatively that the cluster is in a disturbed\ndynamical state, consistent with the majority of phoenices and relics being\nhosted by merging clusters. We discuss the implications of relying on\nmorphology and low-resolution imaging alone for the classification of such\nsources and highlight the usefulness of the MHz to GHz radio spectrum in\nclassifying these types of emission. Finally, we discuss the benefits and\nlimitations of using the MWA Phase II in conjunction with other instruments for\ndetailed studies of diffuse, steep-spectrum, non-thermal radio emission within\ngalaxy clusters.\n