Galaxy And Mass Assembly (GAMA)

the bright void galaxy population in the optical and mid-IR

S. J. Penny*, Michael J I Brown, Kevin A. Pimbblet, M. E. Cluver, D. J. Croton, Matt Owers, Rebecca Lange, Mehmet Alpaslan, Ivan Baldry, J. Bland-Hawthorn, Sarah Brough, Simon P. Driver, Benne W. Holwerda, Andrew Hopkins, T. H. Jarrett, Heath Jones, Lee S. Kelvin, M. A. Lara-Lopez, Jochen Liske, Angel Lopez Sanchez & 5 others Jon Loveday, M. Meyer, Peder Norberg, A. S. G. Robotham, M. Rodrigues

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

We examine the properties of galaxies in the Galaxies and Mass Assembly (GAMA) survey located in voids with radii > 10 h -1 Mpc. Utilizing the GAMA equatorial survey, 592 void galaxies are identified out to z ≈ 0.1 brighter than M r = -18.4, our magnitude completeness limit. Using the W versus [N II]/Hα (WHAN) line strength diagnostic diagram, we classify their spectra as star forming, AGN, or dominated by old stellar populations. For objects more massive than 5×10 9 M , we identify a sample of 26 void galaxies with old stellar populations classed as passive and retired galaxies in the WHAN diagnostic diagram, else they lack any emission lines in their spectra. When matched to Wide-field Infrared Survey Explorer mid-IR photometry, these passive and retired galaxies exhibit a range of mid-IR colour, with a number of void galaxies exhibiting [4.6] - [12] colours inconsistent with completely quenched stellar populations, with a similar spread in colour seen for a randomly drawn non-void comparison sample. We hypothesize that a number of these galaxies host obscured star formation, else they are star forming outside of their central regions targeted for single-fibre spectroscopy. When matched to a randomly drawn sample of non-void galaxies, the void and non-void galaxies exhibit similar properties in terms of optical and mid-IR colour, morphology, and star formation activity, suggesting comparable mass assembly and quenching histories. A trend in mid-IR [4.6] - [12] colour is seen, such that both void and non-void galaxies with quenched/passive colours < 1.5 typically have masses higher than 10 10 M , where internally driven processes play an increasingly important role in galaxy evolution.

Original languageEnglish
Pages (from-to)3519-3539
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Volume453
Issue number4
DOIs
Publication statusPublished - 11 Nov 2015

Keywords

  • galaxies: evolution
  • galaxies: general
  • infrared: galaxies
  • DIGITAL SKY SURVEY
  • ACTIVE GALACTIC NUCLEI
  • STAR-FORMATION HISTORIES
  • COLOR-MAGNITUDE RELATION
  • DARK-MATTER MODEL
  • DATA RELEASE 7
  • REDSHIFT SURVEY
  • STELLAR MASS
  • FORMATION RATES
  • RED SEQUENCE

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