Rotation–activity relations studied for our sample, as discussed in Sect. 5.1. Top left: normalized X-ray luminosity L_X/L_bol as function of the Rossby number Ro for 113 M dwarfs. The corresponding best-fit relation from Reiners et al. (2014) is plotted in thick grey lines. Top right: normalized Hα luminosity L_Hα/L_bol as function of Ro for 196 M dwarfs. The best-fit broken power-law relation from Newton et al. (2017) is displayed in grey. Bottom left: normalized Ca II H&K emission () as function of Ro for 144 stars. The marked outlier J14257+236W was not included in our fit. Best-fit relations from Astudillo-Defru et al. (2017a) and Boudreaux et al. (2022) are overplotted. Bottom right: average magnetic field strength ⟨B⟩ versus Ro for 162 stars. In all plots, earlier-, mid-, and later-type M dwarfs (i.e., M_⋆ > 0.35 M_⊙, 0.35 M_⊙ > M_⋆ > 0.2 M_⊙, < 0.2 M_⊙) are denoted by large blue, medium-sized orange, and small red circles, respectively. Stars with non-debated period values are fitted with broken power laws, shown in broken dashed lines in black (whole sample), blue (> 0.35M_⊙), and green (≤0.35 M_⊙). Stars with debated periods are marked by black ‘X’s, and with provisional periods they are marked by black ‘+’s. Known SBs are represented by magenta asterisks. Where applicable, best-fit rotation-activity relations for subsamples within defined mass ranges are overlaid (black dotted lines: whole sample, blue dashed lines: > 0.35 M_⊙, red dash-dotted lines: ≤0.35 M_⊙).