Discovery of a Radio Halo (and Relic) in a M500<2×1014 M⊙ Cluster
Abstract
Radio halos are diffuse synchrotron sources observed in dynamically unrelaxed galaxy clusters. Current observations and models suggest that halos trace turbulent regions in the intracluster medium where mildly relativistic particles are reaccelerated during cluster mergers. Due to the higher luminosities and detection rates with increasing cluster mass, radio halos have been mainly observed in massive systems ( ${M}_{500}\gtrsim 5\times {10}^{14}$ ${M}_{\odot }$ ). Here, we report the discovery of a radio halo with a largest linear scale of750 kpc in PSZ2G145.92-12.53 (z0.03) using LOw Frequency ARray (LOFAR) observations at 120168 MHz. With a mass of ${M}_{500}=(1.9\pm 0.2)\times {10}^{14}$ ${M}_{\odot }$ and a radio power at 150MHz of ${P}_{150}=(3.5\pm 0.7)\times {10}^{23}$ W Hz1, this is the least powerful radio halo in the least massive cluster discovered to date. Additionally, we discover a radio relic with a mildly convex morphology at 1.7 Mpc from the cluster center. Our results demonstrate that LOFAR has the potential to detect radio halos even in low-mass clusters, where the expectation to form them is very low (5) based on turbulent reacceleration models. Together with the observation of large samples of clusters, this opens the possibility to constrain the low end of the powermass relation of radio halos.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2021
- DOI:
- 10.3847/2041-8213/ac0636
- arXiv:
- arXiv:2105.14025
- Bibcode:
- 2021ApJ...914L..29B
- Keywords:
-
- Galaxy clusters;
- Intracluster medium;
- Extragalactic radio sources;
- Radio astronomy;
- Radio interferometry;
- Extended radiation sources;
- Non-thermal radiation sources;
- 584;
- 858;
- 508;
- 1338;
- 1346;
- 504;
- 1119;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 8 pages, 5 figures, 1 table (including appendix). Accepted for publication in ApJL