Comparison with previous studies. Left: black points represent radio halo clusters from the literature, red points are newly discovered radio halos, and blue squares are new candidate radio halos. Right: comparison with Cuciti et al. (2021a) rescaled at 150 MHz assuming α = −1.3. Black points and arrows are radio halos and upper limits from the LOFAR sample, and blue stars and arrows are radio halos and upper limits in Cuciti et al. (2021a). The black solid line is the same as in Fig. 2 (right). The dashed blue line is the correlation obtained for the Cuciti et al. (2021a) sample including radio halos and USSRH.