Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Structural and Stellar Population Properties vs. Bulge Types in Sloan
  Digital Sky Survey Central Galaxies   This paper studies pseudo-bulges (P-bulges) and classical bulges (C-bulges)
in Sloan Digital Sky Survey central galaxies using the new bulge indicator
$\Delta\Sigma_1$, which measures relative central stellar-mass surface density
within 1 kpc. We compare $\Delta\Sigma_1$ to the established bulge-type
indicator $\Delta\langle\mu_e\rangle$ from Gadotti (2009) and show that
classifying by $\Delta\Sigma_1$ agrees well with $\Delta\langle\mu_e\rangle$.
$\Delta\Sigma_1$ requires no bulge-disk decomposition and can be measured on
SDSS images out to $z = 0.07$. Bulge types using it are mapped onto twenty
different structural and stellar-population properties for 12,000 SDSS central
galaxies with masses 10.0 < log $M_*$/$M_{\odot}$ < 10.4. New trends emerge
from this large sample. Structural parameters show fairly linear log-log
relations vs. $\Delta\Sigma_1$ and $\Delta\langle\mu_e\rangle$ with only
moderate scatter, while stellar-population parameters show a highly non-linear
"elbow" in which specific star-formation rate remains roughly flat with
increasing central density and then falls rapidly at the elbow, where galaxies
begin to quench. P-bulges occupy the low-density end of the horizontal arm of
the elbow and are universally star-forming, while C-bulges occupy the elbow and
the vertical branch and exhibit a wide range of star-formation rates at fixed
density. The non-linear relation between central density and star-formation
rate has been seen before, but this mapping onto bulge class is new. The wide
range of star-formation rates in C-bulges helps to explain why bulge
classifications using different parameters have sometimes disagreed in the
past. The elbow-shaped relation between density and stellar indices suggests
that central structure and stellar-populations evolve at different rates as
galaxies begin to quench.

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The categories of this paper are: nlin
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: plasm-ph
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The categories of this paper are: math
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: q-bio
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: physics
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The categories of this paper are: chem-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg