Evidence of bar--driven secular evolution in the gamma--ray narrow--line
  Seyfert 1 galaxy FBQS J164442.5+261913
  We present near--infrared (NIR) imaging of FBQS J164442.5+261913, one of the
few $\gamma$--ray emitting Narrow Line Seyfert 1 ($\gamma-$NLSy1) galaxies
detected at high significance level by $Fermi$--LAT. This study is the first
morphological analysis performed of this source and the third performed of this
class of objects. Conducting a detailed two--dimensional modeling of its
surface brightness distribution and analysing its $J-K_s$ colour gradients, we
find that FBQS J164442.5+261913 is statistically most likely hosted by a barred
lenticular galaxy (SB0). We find evidence that the bulge in the host galaxy of
FBQS J164442.5+261913 is not classical but pseudo, against the paradigm of
powerful relativistic jets exclusively launched by giant ellipticals. Our
analysis, also reveal the presence of a ring with diameter equalling the bar
length ($r_{bar} = 8.13\ \textrm{kpc}\pm 0.25$), whose origin might be a
combination of bar--driven gas rearrangement and minor mergers, as revealed by
the apparent merger remnant in the $J$--band image. In general, our results
suggest that the prominent bar in the host galaxy of FBQS J164442.5+261913 has
mostly contributed to its overall morphology driving a strong secular
evolution, which plays a crucial role in the onset of the nuclear activity and
the growth of the massive bulge. Minor mergers, in conjunction, are likely to
provide the necessary fresh supply of gas to the central regions of the host
galaxy.
