Kpc-scale radio-jets in narrow-line Seyfert 1 galaxies
  Narrow-Line Seyfert 1 galaxies (NLS1s) are generally believed to be
radio-quiet Active Galactic Nuclei (AGN) with relatively less-massive
(10$^{5}$$-$10$^{8}$~M$_{\odot}$) Super-Massive Black Holes (SMBH). Using the
FIRST radio detections of hitherto the largest sample of 11101
optically-selected NLS1s we find a rather uncommon population of 55 NLS1s with
Kiloparsec-Scale Radio structures (KSRs). We note that the number of NLS1s with
KSRs found in our study is only a lower limit considering the effects of
sensitivity, spatial resolution and projection, and hence, the number of NLS1s
with KSRs may be more common than thought earlier. The NLS1s with KSRs are
distributed across a wide range of redshifts, flux densities and luminosities.
NLS1s with KSRs tend to exhibit steep radio spectra and are likely to be
misaligned version of blazar-like NLS1s. The ratio of IR to radio flux density
(q$_{\rm 22~{\mu}m}$ $=$ log[S$_{\rm 22~{\mu}m}$/S$_{\rm 1.4~GHz}$]) versus
radio luminosity plot suggests that KSRs are mostly powered by AGN, while KSRs
in NLS1s with low radio luminosity (L$_{\rm 1.4~GHz}$ $<$ 10$^{23.5}$
W~Hz$^{-1}$) may have a contribution from circumnuclear starburst. The trend
shown by KSRs in radio luminosity versus radio-size plot indicates that the
radio-jets resulting in KSRs are either in the early phase of their evolution
or inefficient to grow beyond the host galaxy.
