J-PLUS: Spectroscopic validation of H<i>α</i> emission line maps in spatially resolved galaxies

Aims . We present a dedicated automated pipeline to construct spatially resolved emission H α +[NII] maps and to derive the spectral energy distributions (SEDs) in 12 optical filters (five broad and seven narrow and medium) of H α emission line regions in nearby galaxies (z &lt; 0.0165) observed by the Javalambre Photometric Local Universe Survey (J-PLUS). Methods . We used the J 0660 filter of 140 Å width centered at 6600 Å to trace H α + [NII] emission, and r and i broad bands were used to estimate the stellar continuum. We created pure emission line images after the continnum subtraction, where the H α emission line regions were detected. This method was also applied to integral field unit (IFU) spectroscopic data from PHANGS-MUSE, CALIFA, and MaNGA surveys by building synthetic narrow bands based on J-PLUS filters. The studied sample includes the cross-matched catalog of these IFU surveys with the J-PLUS third data release (DR3), amounting to two PHANGS-MUSE, 78 CALIFA, and 78 MaNGA galaxies at z &lt; 0.0165, respectively. Results . We compared the H α +[NII] radial profiles from J-PLUS and the IFU surveys, finding good agreement within the expected uncertainties. We also compared the SEDs from the emission line regions detected in J-PLUS images, reproducing the main spectral features present in the spectroscopic data. Finally, we compared the emission fluxes from the J-PLUS and IFU surveys accounting for scale differences, finding a difference of only 2% with a dispersion of 7% in the measurements. Conclusions . The J-PLUS data provide reliable spatially resolved H α +[NII] emission maps for nearby galaxies. We provide the J-PLUS DR3 catalog for the 158 galaxies with IFU data, including emission maps, SEDs of star-forming clumps, and radial profiles.