SIMBAD references

We study a sample of narrow-line Seyfert 1 galaxies (NLS1) in their optical and radio features to understand the differences between their radio silent, radio-loud, and radio-quiet subclasses. We first show that the different redshift and mass distributions of radio-loud and radio-quiet NLS1s could be ascribed to observational biases. We then present a geometrical model according to which most of the different observational features of radio-loud and radio-quiet NLS1s are ascribed to the orientation of an intrinsically structured jet. We estimate the fraction of intrinsically jetted sources among NLS1s that justifies the observed radio-detected population. Noticeably, under the assumptions of the geometrical model, we derive a fraction of jetted sources significantly larger than in standard AGN.