Distribution of radio core prominence at 144 MHz and 1.4 GHz. Left panel: The distribution of the radio core prominence at 144 MHz, CP₁₄₄ of the core-D AGNs sample, and the final sample of 69 candidate restarted galaxies as discussed in Sect. 3.5. The CP₁₄₄ was estimated using the peak core flux densities measured directly from the LOFAR 6″ image and the total flux densities measured from the LOFAR 18″ image. We note that J105922.02+523902.1 with CP₁₄₄ = 5.0 is excluded in this plot for illustration purposes. However, this source is identified as a broad line AGNs in Sect. 3.4 and excluded from the final sample of candidate restarted galaxies presented in Sect. 3.5. Right panel: The distribution of the radio core prominence at 1.4 GHz, CP₁₄₀₀ of the final sample of 69 candidate restarted galaxies as discussed in Sect. 3.5. The distribution of limits (63 upper and six lower limits) is shown in olive color (see text for details). The mean and median values of the CP distribution are 0.35 and 0.26 respectively. We note that the candidate restarted galaxies selected based on steep spectrum core (SSC), inverted spectrum core (ISC), and ultra-steep spectrum (USS) of extended emission presented in Sect. 3.5 are also included in both plots.