tokens: defined as AGNs all galaxies beyond the left line in the BPT ([NII]/H α ) diagram. In specific cases we refer only to “pure” AGNs, namely galaxies above the curve defined by Kewley et al. (2001) in the BPT ([NII]/H α ) diagram. Also, galaxies classified as PAS or PSB (and RET in the WHAN diagnostic) are always held together. Fig. 3 Nuclear diagnostic diagrams for the whole HRS sample limited to emission-line objects with S ∕ N > 3. In the left BPT diagram panel , the broken separation line between AGNs (red) and TRAN (pink) galaxies is from Kewley et al. (2001) , while the dotted separation line between TRAN (pink) and HII region-like nuclei (blue) is from K03. In the second BPT diagram panel , the extreme starburst classification line is from Kewley et al. (2001) , while the separation between LINER (pink) and SEY (red) is from Kewley et al. (2006) . We note that the pink filled symbols refer to different types of objects in the three diagrams. The third panel reports the BPT diagram for the minority of galaxies (101) with [OI] in emission. In the WHAN diagram the separations between the different classes are from Gavazzi et al. (2011) . Fig. 4 Integrated diagnostic diagrams for emission-line objects with S ∕ N > 3. Brokenseparations in the diagrams are the same as in Fig. 3 . Despite the different populations and classification criteria, the WHAN and the BPT nuclear diagnostics give consistent results (see Table 2 ). Hereafter, two different percentages are always reported, one is the value resulting from one of the [NII]/H α or [SII]/H α BPT diagrams and the other is from the WHAN diagram. Between 53 and 64% of the nuclear spectra are HII region-like nuclei. The remaining percentage is divided between AGNs (21–27%) and PAS (15–21%). The “pure” AGNs are half of the AGNs percentage: 7–13%. These are galaxies ionized by a SMBH. Restricting to the 254 LTGs alone, the statistics is altered (see right columns of Table 2 ): the HII-regions increase to 67–77%; the AGNs become 21–27%; and the PAS spectra decrease to 2–7%. The latter class includes two PSB galaxies: HRS-116 and HRS-195. These two objects show a late-type morphology, with a central bulge and spiral arms, but the SF activity has been stopped suddenly. Also HRS-164 is a LTG with a PAS spectrum: its morphology shows a strong barred structure in the center, but it is an old and red object. A comparison between the nuclear and integrated spectral classifications can be performed among the subsample of HRS galaxies with available nuclear and integrated classification (see Figs. 5 , 7 , and 8 ); the subsample is reported in Table 3 . This comparison provides information about how the excitation properties of galaxies change from the center to the outskirts. As can be seen in the three figures, AGNs represent 18–26% in the nuclear spectra; while in the integrated they decrease to 4–11%. HII-regions are 59–71% in the nuclear classification, becoming 69–84% among the integrated spectra. PAS
ner_tags: O O O O O O O O O O O B-ObservationalTechniques B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O B-ObservationalTechniques B-Wavelength I-Wavelength O O O O O O O O O O O O O B-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O O O O B-Dataset I-Dataset O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula O O O B-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O B-Citation O O O B-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O B-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O O O O B-ObservationalTechniques I-ObservationalTechniques O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O B-ObservationalTechniques O O B-ObservationalTechniques I-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength O B-Wavelength I-Wavelength B-ObservationalTechniques I-ObservationalTechniques O O O O O O B-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O