Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for the concurrent growth of thick discs and central mass
  concentrations from S$^4$G imaging   We have produced $3.6\mu{\rm m}+4.5\mu{\rm m}$ vertically integrated radial
luminosity profiles of 69 edge-on galaxies from the Spitzer Survey of Stellar
Structure in Galaxies (S$^4$G). We decomposed the luminosity profiles into a
disc and a central mass concentration (CMC). These fits, combined with
thin/thick disc decompositions from our previous studies, allow us to estimate
the masses of the CMCs, the thick discs, and the thin discs ($\mathcal{M}_{\rm
CMC}$, $\mathcal{M}_{\rm T}$, and $\mathcal{M}_{\rm T}$). We obtained atomic
disc masses ($\mathcal{M}_{\rm g}$) from the literature. We then consider the
CMC and the thick disc to be dynamically hot components and the thin disc and
the gas disc to be dynamically cold components. We find that the ratio between
the mass of the hot components and that of the cold components,
$(\mathcal{M}_{\rm CMC}+\mathcal{M}_{\rm T})/(\mathcal{M}_{\rm
t}+\mathcal{M}_{\rm g})$, does not depend on the total galaxy mass as described
by circular velocities ($v_{\rm c}$). We also find that the higher the $v_{\rm
c}$, the more concentrated the hot component of a galaxy. We suggest that our
results are compatible with having CMCs and thick discs built in a short and
early high star forming intensity phase. These components were born thick
because of the large scale height of the turbulent gas disc in which they
originated. Our results indicate that the ratio between the star forming rate
in the former phase and that of the formation of the thin disc is of the order
of 10, but the value depends on the duration of the high star forming intensity
phase.

36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat