Characteristics of the galaxies selected with a DP feature in their emission lines. From left to right: first panel: flux ratio ϕ_max/ϕ_min of the stronger line divided by the weaker line for the individual emission lines Hαλ6565, [OIII]λ5008, Hβλ4863 and [NII]λ6585. We display the Hαλ6565 and [OIII]λ5008 emission line ratios of the objects found in Maschmann & Melchior (2019) with blue and re hatched surfaces. The other panels display parameters computed on the stacked spectra (see Sect. 2.2.2). Second panel: velocity difference Δv between the two peak components taken from the stacking procedure. Third (resp. fourth) panel: amplitude (resp. velocity dispersion) ratio of the stronger and weaker line components of the stacked spectra.