Optical spectroscopy of type-2 LINERs
  Type-2 Low-ionization Narrow Emission-line Regions (LINERs) have been
optically classified with the Palomar data as not presenting a broad component
in the Balmer emission lines associated to the Broad Line Region (BLR) of the
Active Galactic Nuclei (AGN). We unveil the presence of different kinematic
components of emission lines in the nuclear region of a sample of local
(z$\leq$0.022) type-2 LINERs. We focus on the analysis of their true nature by
means of the detection (or not) of a broad component originated in the BLR.
Additionally, we search for the possible presence of non-rotational motions
such as outflows. We have applied a decomposition of the nuclear emission lines
using a spectroscopic analysis of the optical spectra of 9 type-2 LINERs of
intermediate-resolution data retrieved from the Hubble Space Telescope (HST)
archive. The study is completed with archival spectra from the Double
Spectrograph from the Palomar Observatory. The emission line fitting reveals
the presence of a broad component associated to the BLR in 6 out of the 9
galaxies for the space-based data, and for 2 out of the 8 from the ground-based
spectra. The velocity dispersion of two galaxies (NGC 4486 and NGC 4594)
measured in HST/STIS data suggest the presence of outflows. The results
indicate that the spatial resolution plays a major role in the detection of the
BLR, as it appears diluted in the ground-based data (even after removing
stellar contribution). This is also true for the emission line diagnostics, as
the contaminant light contributes to lower emission line ratios towards the
star-forming area of standard BPTs. We propose to reclassify NGC4594 as a
type-1 LINER, since a BLR component is seen in both space- and ground-based
spectra. We find ambiguous results for the BLR component of NGC 4486. The
modest outflow detection in our sample may indicate that they are not as
frequent as for type-1 LINERs.
