Bibcode
Masegosa, J.; Márquez, I.; Ramirez, A.; González-Martín, O.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 527, id.A23
Fecha de publicación:
3
2011
Revista
Número de citas
43
Número de citas referidas
40
Descripción
To get insight into the nature of the ionized gas in the nuclear region
of LINERs, we performed a study of HST Hα imaging of 32 LINERs.
The main conclusion from this analysis is that, for the large majority
of LINERs (84%), an unresolved nuclear source has been identified along
with extended emission with equivalent sizes ranging from a few tens to
a few hundredths of parsecs. Their morphologies do not appear to be
homogeneous, since they are grouped into three classes: nuclear outflow
candidates (42%), core-halo morphologies (25%), and nuclear spiral disks
(14%). Clumpy structures reminiscent of young stellar clusters are not a
common property of LINERs. The remaining five galaxies are too dusty to
allow a clear view of the ionized gas distribution. A size-luminosity
relation was found between the equivalent radius of the Hα
emission and the (2-10 keV) X-ray luminosities. Both ionized gas
morphologies and the size-luminosity relation are indistinguishable from
those of low-luminosity Seyferts, suggesting the same origin for the NLR
of LINERs and Seyferts. A relation between soft X-rays and ionized gas
has also been suggested for the first time in LINERs. From
multiwavelength data, only four out of the 32 LINERs show no evidence of
the AGN nature of their nuclear sources from multiwavelength data, but
extremely obscured AGNs cannot be discarded given the Compton-thick
signatures of their X-ray emission. For the confirmed AGN LINERs, their
Hα imaging favour core-halo and outflow morphologies (65% of the
cases). Finally, their calculated Eddington ratios show that our LINER
sources radiate in the sub-Eddington regime, with core-halo systems
having on average higher Eddington ratios than do outflow candidates.
Appendix and Figs. 2 and 6 are only available in electronic form at http://www.aanda.org