Galaxy And Mass Assembly (GAMA): the life and times of L★ galaxies

Robotham, A.S.G.; Liske, J.; Driver, S.P.; Sansom, A.E.; Baldry, I.K.; Bauer, A.E.; Bland-Hawthorn, J.; Brough, S.; Brown, M.J.I.; Colless, M.; Christodoulou, L.; Drinkwater, M.J.; Grootes, M.W.; Hopkins, A.M.; Kelvin, L.S.; Norberg, P.; Loveday, J.; Phillipps, S.; Sharp, R.; Taylor, E.N.; Tuffs, R.J.

doi:10.1093/mnras/stt156

Galaxy And Mass Assembly (GAMA): the life and times of L★ galaxies

Robotham, A.S.G.; Liske, J.; Driver, S.P.; Sansom, A.E.; Baldry, I.K.; Bauer, A.E.; Bland-Hawthorn, J.; Brough, S.; Brown, M.J.I.; Colless, M.; Christodoulou, L.; Drinkwater, M.J.; Grootes, M.W.; Hopkins, A.M.; Kelvin, L.S.; Norberg, P.; Loveday, J.; Phillipps, S.; Sharp, R.; Taylor, E.N.; Tuffs, R.J.

Authors

A.S.G. Robotham

J. Liske

S.P. Driver

A.E. Sansom

I.K. Baldry

A.E. Bauer

J. Bland-Hawthorn

S. Brough

M.J.I. Brown

M. Colless

L. Christodoulou

M.J. Drinkwater

M.W. Grootes

A.M. Hopkins

L.S. Kelvin

Professor Peder Norberg peder.norberg@durham.ac.uk
Professor

J. Loveday

S. Phillipps

R. Sharp

E.N. Taylor

R.J. Tuffs

Abstract

In this work, we investigate in detail the effects the local environment (groups and pairs) has on galaxies with stellar mass similar to the Milky Way (L* galaxies). A volume limited sample of 6150 galaxies are visually classified to determine the emission features, morphological type and presence of a disc. This large sample allows for the significant characteristics of galaxies to be isolated (e.g. stellar mass and group halo mass), and their codependencies determined. We observe that galaxy–galaxy interactions play the most important role in shaping the evolution within a group halo; the main role of halo mass is in gathering the galaxies together to encourage such interactions. Dominant pair galaxies find their overall star formation enhanced when the pair's mass ratio is close to 1; otherwise, we observe the same galaxies as we would in an unpaired system. The minor galaxy in a pair is greatly affected by its companion galaxy, and while the star-forming fraction is always suppressed relative to equivalent stellar mass unpaired galaxies, it becomes lower still when the mass ratio of a pair system increases. We find that, in general, the close galaxy–galaxy interaction rate drops as a function of halo mass for a given amount of stellar mass. We find evidence of a local peak of interactions for Milky Way stellar mass galaxies in Milky Way halo mass groups. Low-mass haloes, and in particular Local Group mass haloes, are an important environment for understanding the typical evolutionary path of a unit of stellar mass. We find compelling evidence for galaxy conformity in both groups and pairs, where morphological type conformity is dominant in groups, and emission class conformity is dominant in pairs. This suggests that group scale conformity is the result of many galaxy encounters over an extended period of time, while pair conformity is a fairly instantaneous response to a transitory interaction.

Citation

Robotham, A., Liske, J., Driver, S., Sansom, A., Baldry, I., Bauer, A., …Tuffs, R. (2013). Galaxy And Mass Assembly (GAMA): the life and times of L★ galaxies. Monthly Notices of the Royal Astronomical Society, 431(1), 167-193. https://doi.org/10.1093/mnras/stt156

Journal Article Type	Article
Publication Date	May 1, 2013
Deposit Date	Jun 3, 2014
Publicly Available Date	Jun 27, 2014
Journal	Monthly Notices of the Royal Astronomical Society
Print ISSN	0035-8711
Electronic ISSN	1365-2966
Publisher	Royal Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	431
Issue	1
Pages	167-193
DOI	https://doi.org/10.1093/mnras/stt156
Keywords	Large-scale structure of Universe.

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This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2013 The Authors Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.