Characterization of a sample of intermediate-type active galactic nuclei. II. Host bulge properties and black hole mass estimates

We present a study of the host bulge properties and their relations with the black hole mass for a sample of 10 intermediate-type active galactic nuclei (AGNs). Our sample consists mainly of early-type spirals, four of them hosting a bar. For 70⁺¹⁰ _-17% of the galaxies, we have been able to determine the type of the bulge, and find that these objects probably harbor a pseudobulge or a combination of classical bulge/pseudobulge, suggesting that pseudobulges might be frequent in intermediate-type AGNs. In our sample, 50% ± 14% of the objects show double-peaked emission lines. Therefore, narrow double-peaked emission lines seem to be frequent in galaxies harboring a pseudobulge or a combination of classical bulge/pseudobulge. Depending on the bulge type, we estimated the black hole mass using the corresponding M _BH-σ* relation and found them within a range of 5.69 ± 0.21 < log M ^σ*_BH < 8.09 ± 0.24. Comparing these M ^σ*_BH values with masses derived from the FWHM of Hβ and the continuum luminosity at 5100 Å from their SDSS-DR7 spectra (M _BH), we find that 8 out of 10 (80⁺⁷ _-17%) galaxies have black hole masses that are compatible within a factor of 3. This result would support that M _BH and M ^σ*_BH are the same for intermediate-type AGNs, as has been found for type 1 AGNs. However, when the type of the bulge is taken into account, only three out of the seven (43⁺¹⁸ _-15%) objects of the sample have their M ^σ* _BH and M _BH compatible within 3σ errors. We also find that estimations based on the M _BH-σ* relation for pseudobulges are not compatible in 50% ± 20% of the objects.