Bibcode
Comerón, S.; Elmegreen, B. G.; Salo, H.; Laurikainen, E.; Holwerda, B. W.; Knapen, J. H.
Bibliographical reference
Astronomy and Astrophysics, Volume 571, id.A58, 16 pp.
Advertised on:
11
2014
Journal
Citations
40
Refereed citations
35
Description
We have produced 3.6 μm + 4.5 μm vertically integrated radial
luminosity profiles of 69 edge-on galaxies from the Spitzer Survey of
Stellar Structure in Galaxies (S4G). 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 (ℳCMC, ℳT,
and ℳT). We obtained atomic disc masses
(ℳg) 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,
(ℳCMC + ℳT)/(ℳt +
ℳg), does not depend on the total galaxy mass as
described by circular velocities (vc). We also find that the
higher the vc, 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.
Appendix A is available in electronic form at http://www.aanda.org
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