Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Emission line ratios for the Circumgalactic Medium and the "Bimodal"
  Nature of Galaxies   We find significantly different diagnostic emission line ratios for the
circumgalactic gas associated with galaxies of stellar masses above and below
$10^{10.4}$ M$_\odot$ using SDSS spectroscopy. Specifically, in a sample of
17,393 galaxies, intersected by 18,535 lines of sight at projected radii
between 10 and 50 kpc, we stack measured fluxes for nebular strong emission
lines, [O {\small III}] $\lambda$5007, H$\alpha$ and [N {\small II}]
$\lambda6583$, and find that the gas surrounding the lower mass galaxies
exhibits similar line ratios to those of gas ionized by star formation and that
surrounding the higher mass galaxies similar to those of gas ionized by AGN or
shocks. This finding highlights yet another characteristic of galaxies that is
distinctly different above and below this stellar mass threshold, but one that
is more closely connected to the gas accretion behavior hypothesized to be
responsible for this dichotomy.

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The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg