2021/05/28 by A. Botteon, R. Cassano, R. J. van Weeren +12 · 1 voice
Physics and Astronomy · #astro-ph.CO #astro-ph.GA #astro-ph.HE
paper · pdf · doi:10.3847/2041-8213/ac0636
8 pages, 5 figures, 1 table (including appendix). Accepted for publication in ApJL
arxiv created 2021/05/28 · arxiv published 2021/05/28 · arxiv updated 2021/06/30
Radio halos are diffuse synchrotron sources observed in dynamically unrelaxed galaxy clusters. Current observations and models suggest that halos trace turbulent regions in the intra-cluster medium where mildly relativistic particles are re-accelerated during cluster mergers. Due to the higher luminosities and detection rates with increasing cluster mass, radio halos have been mainly observed in massive systems (M500 \gtrsim 5 ×1014 M_\odot). Here, we report the discovery of a radio halo with a largest linear scale of ≃750 kpc in PSZ2G145.92-12.53 (z=0.03) using LOFAR observations at 120-168 MHz. With a mass of M500 = (1.9±0.2) × 1014 M_\odot and a radio power at 150 MHz of P150 = (3.5 ± 0.7) × 1023 W/Hz, 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 re-acceleration models. Together with the observation of large samples of clusters, this opens the possibility to constrain the low end of the power-mass relation of radio halos.