A Deeply Buried Narrow-Line Seyfert 1 Nucleus Uncovered in Scattered
  Light
  We present spectropolarimetric and spectrophotometric observations of the
peculiar active galactic nucleus (AGN) SDSS J120300.19+162443.7 (hereafter
J1203+1624) at $z=0.1656$. Its optical total flux spectra clearly show broad
emission lines (BELs) in H$\alpha$ and H$\beta$. After removal of narrow
emission lines (NELs), the full width at half maximum of the lorentzian BEL is
$FWHM_{\rm BEL} \approx 1,270$ km s$^{-1}$, fulfilling the conventional
definition of a narrow line Seyfert 1 (NLS1) galaxy. However, its NELs are
unprecedentedly strong when compared to type 1AGNs. This, together with its
large MIR excess ($g-W_4 = 13.172$ mag), implies that the observer and the
narrow emission line region (NELR) might see a different ionization continuum.
Our optical spectropolarimetry confirms its type 2 nature by detecting a
polarized blue continuum and Balmer BELs ($FWHM_{\rm Polarized~BEL} \approx
1,183$ km s$^{-1}$), with a high polarization degree of $> 20$% in the blue
wing. The mass and Eddington rate of the central black hole is estimated based
on both transmitted and scattered AGN radiation, which is $M_{\bullet} < 2.9
\times 10^7 M_\odot$ and $L_{\rm bol}/L_{\rm Edd} > 1.5$. Severe extinction of
the AGN emission also enables a clear view of the compact host galaxy.
Discovery of J1203+1624 suggests that NLS1 follows AGN unfication scheme,
studying of its analogs could blaze a new trail for exploring the connection
between black hole growth and star formation in the host galaxy. Interesting
features of J1203+1624 like the peculiar NELs, inflowing scattering clouds
within sublimation radius are worth detailed follow-ups in the future.
