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

Smriti Mahajan; Michael J. Drinkwater; S. Driver; Lee S. Kelvin; A. M. Hopkins; I. Baldry; S. Phillipps; J. Bland-Hawthorn; S. Brough; J. Loveday; Samantha J. Penny; A. S. G. Robotham

doi:10.1093/mnras/stu2009

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

Smriti Mahajan, Michael J. Drinkwater, S. Driver, Lee S. Kelvin, A. M. Hopkins, I. Baldry, S. Phillipps, J. Bland-Hawthorn, S. Brough, J. Loveday, Samantha J. Penny, A. S. G. Robotham

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

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 (R_eff), effective surface brightness within R_eff (⟨μ⟩_e), central surface brightness (_μ0) and Sérsic index (n) – obtained by fitting the light profile of 432 galaxies (0.002 < z ≤ 0.02; VikingZ 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, R_eff, SFR, sSFR, M*, M_dust 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.

Original language	English
Pages (from-to)	2967-2984
Journal	Monthly Notices of the Royal Astronomical Society
Volume	446
Issue number	3
Early online date	2 Dec 2014
DOIs	https://doi.org/10.1093/mnras/stu2009
Publication status	Published - 21 Jan 2015

Keywords

Galaxies: dwarf
Galaxies: evolution
Galaxies: fundamental parameters
Galaxies: general
Galaxies: star formation
Galaxies: structure

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10.1093/mnras/stu2009

Mahajan-2014-GAMA-MNRAS-2967
© 2014, the Author(s). This work has been made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at https://doi.org/10.1093/mnras/stu2009
Final published version, 1.74 MB

GAMA Data Release 2
Liske, J. (Creator), Baldry, I. K. (Creator), Driver, S. P. (Creator), Tuffs, R. J. (Creator), Alpaslan, M. (Creator), Andrae, E. (Creator), Brough, S. (Creator), Cluver, M. E. (Creator), Grootes, M. W. (Creator), Gunawardhana, M. L. P. (Creator), Kelvin, L. S. (Creator), Loveday, J. (Creator), Robotham, A. S. G. (Creator), Bamford, S. P. (Creator), Bland-Hawthorn, J. (Creator), Brown, M. J. I. (Creator), Drinkwater, M. J. (Creator), Hopkins, A. M. (Creator), Meyer, M. J. (Creator), Norberg, P. (Creator), Peacock, J. A. (Creator), Agius, N. K. (Creator), Andrews, S. K. (Creator), Bauer, A. E. (Creator), Ching, J. H. Y. (Creator), Colles, M. (Creator), Conselice, C. J. (Creator), Croom, S. M. (Creator), Davies, L. J. M. (Creator), De Propris, R. (Creator), Dunne, L. (Creator), Eardley, E. M. (Creator), Ellis, S. (Creator), Foster, C. (Creator), Frenk, C. S. (Creator), Haußler, B. (Creator), Holwerda, B. W. (Creator), Howlett, C. (Creator), Ibarra, H. (Creator), Jarvis, M. J. (Creator), Jones, D. H. (Creator), Kafle, P. R. (Creator), Lacey, C. G. (Creator), Lange, R. (Creator), Lara-Ĺopez, M. A. (Creator), López-Sánchez, Á. R. (Creator), Maddox, S. (Creator), Madore, B. F. (Creator), McNaught-Roberts, T. (Creator), Moffett, A. J. (Creator), Nichol, R. C. (Creator), Owers, M. S. (Creator), Palamara, D. (Creator), Penny, S. J. (Creator), Phillipps, S. (Creator), Pimbblet, K. A. (Creator), Popescu, C. C. (Creator), Prescott, M. (Creator), Proctor, R. (Creator), Sadler, E. M. (Creator), Sansom, A. E. (Creator), Seibert, M. (Creator), Sharp, R. (Creator), Sutherland, W. (Creator), Vazquez-Mata, J. A. (Creator), van Kampen, E. (Creator), Wilkins, S. M. (Creator), Williams, R. (Creator) & Wright, A. H. (Creator), Galaxy And Mass Assembly (GAMA), 11 Sept 2015
http://www.gama-survey.org/dr2/
Dataset

Cite this

Mahajan, S., Drinkwater, M. J., Driver, S., Kelvin, L. S., Hopkins, A. M., Baldry, I., Phillipps, S., Bland-Hawthorn, J., Brough, S., Loveday, J., Penny, S. J., & 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. https://doi.org/10.1093/mnras/stu2009

@article{002e05fb4af64a8b9cf662e6cb4d7864,

title = "Galaxy And Mass Assembly (GAMA): the unimodal nature of the dwarf galaxy population",

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 S{\'e}rsic index (n) – obtained by fitting the light profile of 432 galaxies (0.002 < z ≤ 0.02; VikingZ 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.",

keywords = "Galaxies: dwarf, Galaxies: evolution, Galaxies: fundamental parameters, Galaxies: general, Galaxies: star formation, Galaxies: structure",

author = "Smriti Mahajan and Drinkwater, {Michael J.} and S. Driver and Kelvin, {Lee S.} and Hopkins, {A. M.} and I. Baldry and S. Phillipps and J. Bland-Hawthorn and S. Brough and J. Loveday and Penny, {Samantha J.} and Robotham, {A. S. G.}",

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doi = "10.1093/mnras/stu2009",

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Mahajan, S, Drinkwater, MJ, Driver, S, Kelvin, LS, Hopkins, AM, Baldry, I, Phillipps, S, Bland-Hawthorn, J, Brough, S, Loveday, J, Penny, SJ & Robotham, ASG 2015, 'Galaxy And Mass Assembly (GAMA): the unimodal nature of the dwarf galaxy population', Monthly Notices of the Royal Astronomical Society, vol. 446, no. 3, pp. 2967-2984. https://doi.org/10.1093/mnras/stu2009

TY - JOUR

T1 - Galaxy And Mass Assembly (GAMA)

T2 - the unimodal nature of the dwarf galaxy population

AU - Mahajan, Smriti

AU - Drinkwater, Michael J.

AU - Driver, S.

AU - Kelvin, Lee S.

AU - Hopkins, A. M.

AU - Baldry, I.

AU - Phillipps, S.

AU - Bland-Hawthorn, J.

AU - Brough, S.

AU - Loveday, J.

AU - Penny, Samantha J.

AU - Robotham, A. S. G.

PY - 2015/1/21

Y1 - 2015/1/21

N2 - 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; VikingZ 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.

AB - 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; VikingZ 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.

KW - Galaxies: dwarf

KW - Galaxies: evolution

KW - Galaxies: fundamental parameters

KW - Galaxies: general

KW - Galaxies: star formation

KW - Galaxies: structure

U2 - 10.1093/mnras/stu2009

DO - 10.1093/mnras/stu2009

M3 - Article

SN - 0035-8711

VL - 446

SP - 2967

EP - 2984

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 3

ER -

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

Abstract

Keywords

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Datasets

GAMA Data Release 2

Cite this