tokens: morphologies (Brinchmann et al. 2004 ). The number of non-AGN decreases steadily as B/T increases, however, there is a significant population (12 per cent of the non-AGN sample) with B/T = 1, i.e. pure elliptical galaxies. Of the 181 pure ellipticals that we classify as non-AGN, only four are unclassifiable via the BPT analysis. 114 are BPT-classified as composite, AGN(non-LINER), or low S/N LINER implying that there is some AGN component in these galaxies, but the radio emission is not significantly enhanced to be selected by our method. The remaining 63 non-AGN pure ellipticals are classified by the BPT analysis as either star forming or low S/N star forming, which is consistent with these galaxies being truly non-AGN. Figure 6. The distribution of bulge-to-total light ratios, which we use as a proxy for galaxy morphology, for the non-AGN galaxies (blue), all AGN i.e. our faint AGN + the BH12 AGN (red), and the faint AGN sample only (green). Non-AGN galaxies have predominantly low B/T values, i.e. are morphological spirals, while almost all BH12 AGN and the faint identified in this work have B/T = 1, i.e. are morphological elliptical galaxies. For the AGN samples, we find that there are few sources with disc-like morphologies (89 per cent have B/T ⩾ 0.5), and the majority of the galaxies have B/T=1, 78 per cent for the total AGN sample and 73 per cent for the faint AGN sample. This also agrees with previous studies that show that radio-loud AGN are preferentially found in massive elliptical galaxies (Wilson Colbert 1995 ; Dunlop et al. 2003 ; Kauffmann et al. 2003 ; Kauffmann, Heckman Best 2008 ). We complete our analysis by briefly checking our morphological results with the local colour–magnitude relation. Using the k-corrected g-band and r-band magnitudes from the MPA–JHU catalogue, we split the sample into red and blue galaxies. We then recreate Fig. 1 showing the density of red sequence and blue cloud galaxies (Fig. 7 ). Galaxies identified as AGN (both the BH12 AGN and those in our faint AGN sample) are typically found on the red sequence that is dominated by early-type galaxies (e.g. Bower, Lucey Ellis 1992 ; Kodama Arimoto 1997 ; Blanton Moustakas 2009 ), in agreement with our results using the bulge-to-total light ratios that find that the majority of AGN have early-type morphology. In contrast, the non-AGN galaxies cover a much broader region of the colour–magnitude diagram and are predominantly in the blue cloud that is typically dominated by star-forming spiral galaxies (e.g. Tully et al. 1998 ; Baldry et al. 2004 ). This is again in agreement with our morphological results where we find that the non-AGN galaxies are disc-dominated. Figure 7. Comparison of the SFRs obtained via optical spectro-photometric data from the SDSS, with the FIRST 1.4 GHz luminosities as in Fig. 1 but coloured by position in the colour–magnitude diagram. Galaxies that are found in the blue cloud are mostly purely star-forming galaxies (shown in
ner_tags: 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 O B-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 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-Wavelength 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-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-Citation O O O O O O O O O B-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 O O O B-Formula I-Formula I-Formula O O O O O O O B-Formula 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-Wavelength O O O O O O O O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation 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 B-Wavelength O B-Wavelength O O O B-Dataset I-Dataset 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-Citation O O O O 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 B-Citation I-Citation I-Citation O B-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 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-Citation I-Citation I-Citation I-Citation 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 O O O O O O O O O B-Survey O O B-Survey B-Wavelength I-Wavelength 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