Galaxy And Mass Assembly (GAMA): the unimodal nature of the dwarf galaxy population

Mahajan, Smriti, Drinkwater, Michael J., Driver, S., Kelvin, Lee S., Hopkins, A. M., Baldry, I., Phillipps, S., Bland-Hawthorn, J., Brough, S., Loveday, J., Penny, Samantha J. and Robotham, A. S. G. (2015) Galaxy And Mass Assembly (GAMA): the unimodal nature of the dwarf galaxy population. Monthly Notices of the Royal Astronomical Society, 446 3: 2967-2984. doi:10.1093/mnras/stu2009

Author Mahajan, Smriti
Drinkwater, Michael J.
Driver, S.
Kelvin, Lee S.
Hopkins, A. M.
Baldry, I.
Phillipps, S.
Bland-Hawthorn, J.
Brough, S.
Loveday, J.
Penny, Samantha J.
Robotham, A. S. G.
Title Galaxy And Mass Assembly (GAMA): the unimodal nature of the dwarf galaxy population
Journal name Monthly Notices of the Royal Astronomical Society   Check publisher's open access policy
ISSN 0035-8711
Publication date 2015-01-21
Year available 2014
Sub-type Article (original research)
DOI 10.1093/mnras/stu2009
Open Access Status DOI
Volume 446
Issue 3
Start page 2967
End page 2984
Total pages 18
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Language eng
Formatted abstract
In this paper we aim to (i) test the number of statistically distinct classes required to classify the local galaxy population and (ii) identify the differences in the physical and star formation properties of visually distinct galaxies. To accomplish this, we analyse the structural parameters – effective radius (Reff), effective surface brightness within Reff (〈μ〉e), central surface brightness (μ0) and Sérsic index (n) – obtained by fitting the light profile of 432 galaxies (0.002 < z ≤ 0.02; Viking Z band), and their spectral energy distribution using multiband photometry in 18 broad-bands to obtain the stellar mass (M*), the star formation rate (SFR), the specific SFR (sSFR) and the dust mass (Mdust), respectively. We show that visually distinct, star-forming dwarf galaxies (irregulars, blue spheroids and low-surface-brightness galaxies) form a unimodal population in a parameter space mapped by 〈μ〉e, μ0, n, Reff, SFR, sSFR, M*, Mdust and (g − i). The SFR and sSFR distribution of passively evolving (dwarf) ellipticals on the other hand, statistically distinguish them from other galaxies with similar luminosity, while the giant galaxies clearly segregate into star-forming spirals and passive lenticulars. We therefore suggest that the morphology classification scheme(s) used in literature for dwarf galaxies only reflect the observational differences based on luminosity and surface brightness among the apparent distinct classes, rather than any physical differences between them.
Keyword Galaxies: dwarf
Galaxies: evolution
Galaxies: fundamental parameters
Galaxies: general
Galaxies: star formation
Galaxies: structure
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID DST-13-0058
Institutional Status UQ
Additional Notes Published online ahead of print 2 Dec 2014

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
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