a) Integrated intensity maps of H¹³CO⁺ (J = 1–0) obtained with PdBI and combined with observations from the IRAM 30 m telescope (the scaling goes from  −2σ to 35σ for field N63 and N12, and from  − 2σ to 60σ for all other fields). Contours show the 3 mm continuum emission, where levels are the same as in Paper I. Crosses indicate the location of 1 mm continuum sources reported in Paper I. Dashed circles indicate the primary beam of the PdBI. Gray ellipses in the left lower corner show the synthesized beam. b) Interferometric line-integrated intensity maps of H¹³CO⁺ (J = 1–0). c) Integrated line intensity maps of H¹³CN (J = 1–0) (over all hyperfine components).