A search for ionised gas outflows in an Halpha imaging atlas of nearby
  LINERs
  Outflows play a major role in the evolution of galaxies. However, we do not
have yet a complete picture of their properties (extension, geometry,
orientation and clumpiness). For low-luminosity Active Galactic Nuclei (AGNs),
in particular, low-ionisation nuclear emission line regions (LINERs), the rate
of outflows and their properties are largely unknown. The main goal of this
work is to create the largest, up-to-date atlas of ionised gas outflow
candidates in a sample of 70 nearby LINERs. We use narrow-band, imaging data to
analyse the morphological properties of the ionised gas nuclear emission of
these galaxies and to identify signatures of extended emission with distinctive
outflow-like morphologies. We obtained new imaging data from ALFOSC/NOT for 32
LINERs. We complemented it with HST archival data for 6 objects and with
results from the literature for other 32 targets. We additionally obtained soft
X-ray data from Chandra archive to compare with the ionised gas. The
distribution of the ionised gas in these LINER shows that $\sim$32% have
bubble-like emission, $\sim$28% show a 'Core-halo', unresolved emission, and
$\sim$21% have a disky-like distribution. Dust lanes prevent a detailed
classification for $\sim$11% of the sample ('Dusty'). If we account for the
kinematical information, available for 60 galaxies, we end up with 48% of the
LINERs with detected outflows/inflows (50% considering only kinematical
information based on Integral Field Spectroscopy). Our results suggest that the
incidence of outflows in LINERs may vary from 41% up to 56%, based on both the
Halpha morphology and the kinematical information from the literature. The
ionised gas is co-spatial with the soft X-ray emission for the majority of
cases ($\sim$60%), so that they may have a common origin. We discuss the use of
Halpha imaging for the pre-selection of candidates likely hosting ionised gas
outflows.
