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

Mahajan, S and Drinkwater, MJ and Driver, S and Kelvin, LS and Hopkins, AM and Baldry, IK and Phillipps, S and Bland-Hawthorn, J and Brough, S and Loveday, J and Penny, SJ and Robotham, ASG (2015) Galaxy And Mass Assembly (GAMA): the unimodal nature of the dwarf galaxy population. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 446 (3). pp. 2967-2984. ISSN 0035-8711

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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 (hμie), central surface brightness (μ0), and S´ersic index (n)), obtained by fitting the light profile of 432 galaxies (0.002 < z 6 0.02; Viking Z-band), and their spectral energy distribution using multi-band photometry in 18 broadbands 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 hμie, 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 starforming 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.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record "Galaxy And Mass Assembly (GAMA): the unimodal nature of the dwarf galaxy population", MNRAS, 446(3), pp.2967-2984 is available online at: http://dx.doi.org/10.1093/mnras/stu2009
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: OXFORD UNIV PRESS
Related URLs:
Date Deposited: 02 Jul 2015 08:47
Last Modified: 07 Sep 2015 14:55
DOI or Identification number: 10.1093/mnras/stu2009
URI: http://researchonline.ljmu.ac.uk/id/eprint/1504

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