Electron density, n_e, measured from the flux ratio of [SII]λ6716/[SII]λ6731. Top: electron density map. Black contours show the Hα flux, pink contours the radio emission observed with FIRST. Bottom: Integrated [SII]λλ6716,6731 spectra of J2345–0449 extracted from regions with electron densities, n_e, below (left panel) and above 600 cm⁻³ (right panel). Data are shown as black histograms, Gaussian fits as orange lines. The line ratio, r, and its uncertainties is listed above each spectrum.