Discovery of a Radio Relic in the Massive Merging Cluster SPT-CL J2023-5535 from the ASKAP-EMU Pilot Survey
Abstract
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 ${\alpha }_{800\,\mathrm{MHz}}^{1088\,\mathrm{MHz}}=-0.76\pm 0.06$ . Our weak-lensing analysis shows that the system is massive ( ${M}_{200}=1.04\pm 0.36\times {10}^{15}\,{M}_{\odot }$ ) 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2020
- DOI:
- 10.3847/1538-4357/aba742
- arXiv:
- arXiv:2007.08244
- Bibcode:
- 2020ApJ...900..127H
- Keywords:
-
- Galaxy clusters;
- Weak gravitational lensing;
- Radio continuum emission;
- Radio telescopes;
- X-ray astronomy;
- 584;
- 1797;
- 1340;
- 1360;
- 1810;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted to ApJ