Discovery of a Radio Relic in the Massive Merging Cluster SPT-CL J2023-5535 from the ASKAP-EMU Pilot Survey

Kim Hyeonghan, M. James Jee, Lawrence Rudnick, David Parkinson, Kyle Finner, Mijin Yoon, Wonki Lee, Gianfranco Brunetti, Marcus Brüggen, Jordan D. Collier, Andrew M. Hopkins, Michał J. Michałowski, Ray P. Norris, Chris Riseley

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12 Citations (Scopus)


The ASKAP-EMU survey is a deep wide-field radio continuum survey designed to cover the entire southern sky and a significant fraction of the northern sky up to +30°. Here, we report a discovery of a radio relic in the merging cluster SPT-CL J2023-5535 at z = 0.23 from the ASKAP-EMU pilot 300 square degree survey (800-1088 MHz). The deep high-resolution data reveal a ∼2 Mpc scale radio halo elongated in the east-west direction, coincident with the intracluster gas. The radio relic is located at the western edge of this radio halo stretched ∼0.5 Mpc in the north-south orientation. The integrated spectral index of the radio relic within the narrow bandwidth is α800MHz1088MHz = -0.76 ± 0.06. Our weak-lensing analysis shows that the system is massive (M200 = 1.04 ± 0.36 × 1015 M⊙) and composed of at least three subclusters. We suggest a scenario, wherein the radio features arise from the collision between the eastern and middle subclusters. Our discovery illustrates the effectiveness of the ASKAP-EMU survey in detecting diffuse emissions in galaxy clusters and when completed, the survey will greatly increase the number of merging cluster detections with diffuse radio emissions.

Original languageEnglish
Article number127
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2020 Sept 10

Bibliographical note

Publisher Copyright:
© 2020. The American Astronomical Society. All rights reserved..

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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