Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SDSS IV MaNGA - Spatially resolved diagnostic diagrams: A proof that
  many galaxies are LIERs   We study the spatially resolved excitation properties of the ionised gas in a
sample of 646 galaxies using integral field spectroscopy data from SDSS-IV
MaNGA. Making use of Baldwin-Philips-Terlevich diagnostic diagrams we
demonstrate the ubiquitous presence of extended (kpc scale) low ionisation
emission-line regions (LIERs) in both star forming and quiescent galaxies. In
star forming galaxies LIER emission can be associated with diffuse ionised gas,
most evident as extra-planar emission in edge-on systems. In addition, we
identify two main classes of galaxies displaying LIER emission: `central LIER'
(cLIER) galaxies, where central LIER emission is spatially extended, but
accompanied by star formation at larger galactocentric distances, and `extended
LIER' (eLIER) galaxies, where LIER emission is extended throughout the whole
galaxy. In eLIER and cLIER galaxies, LIER emission is associated with radially
flat, low H$\alpha$ equivalent width of line emission ($<$ 3 \AA) and stellar
population indices demonstrating the lack of young stellar populations,
implying that line emission follows tightly the continuum due to the underlying
old stellar population. The H$\alpha$ surface brightness radial profiles are
always shallower than $\rm 1/r^{2}$ and the line ratio
[OIII]$\lambda$5007/[OII]$\lambda$3727,29 (a tracer of the ionisation parameter
of the gas) shows a flat gradient. This combined evidence strongly supports the
scenario in which LIER emission is not due to a central point source but to
diffuse stellar sources, the most likely candidates being hot, evolved
(post-asymptotic giant branch) stars. Shocks are observed to play a significant
role in the ionisation of the gas only in rare merging and interacting systems.

3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn