Unveiling the submerged part of the iceberg: radio-loud narrow-line
  Seyfert 1s with SKA
  Narrow-line Seyfert 1 galaxies (NLS1) are active galactic nuclei (AGN) known
to have small masses of the central black hole and high accretion rates. NLS1s
are generally radio-quiet, but a small part of them (about 7\%) are radio-loud.
The recent discovery of powerful relativistic jets in radio-loud NLS1s
(RLNLS1s), emitting at high-energy $\gamma$-rays, opened intriguing questions.
The observed luminosity of the jet is generally weak, smaller than blazars,
although when rescaled for the mass of the central black hole, it becomes of
the same order of magnitude of the latter. The weak luminosity, and hence
observed flux, resulted in a small number of known RLNLS1. From a recent survey
of RLNLS1s, it was found that only 8 out of 42 sources had radio flux density
at 1.4 GHz greater than 100 mJy, while 21 out of 42 had flux density smaller
than 10 mJy. In addition, given the strong variability at all wavelengths, with
present-day facilities RLNLS1s can often only be detected during high activity
periods. The Square Kilometer Array (SKA), with its superior sensitivity, will
break this limit, allowing us to unveil a relatively unknown population of
jetted AGN. We present the results of a study aimed at evaluating the scenario
that could emerge after the advent of SKA.
