Radio galaxies in ZFOURGE/NMBS: no difference in the properties of massive galaxies with and without radio-AGN out to z  = 2.25

In order to reproduce the high-mass end of the galaxy mass distribution, some process must be responsible for the suppression of star formation in the most massive of galaxies. Commonly active galactic nuclei (AGN) are invoked to fulfil this role, but the exact means by which they do so is still the...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2016-01, Vol.455 (3), p.2731-2731
Main Authors: Rees, G A, Spitler, L R, Norris, R P, Cowley, M J, Papovich, C, Glazebrook, K, Quadri, R F, Straatman, C MS, Allen, R, Kacprzak, G G, Labbe, I, Nanayakkara, T, Tomczak, A R, Tran, K -V
Format: Article
Language:English
Subjects:
Active galactic nuclei
Astronomy
Constants
Feedback
Galactic evolution
Galaxies
Luminosity
Red shift
Star & galaxy formation
Star formation
Symbols
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Summary:In order to reproduce the high-mass end of the galaxy mass distribution, some process must be responsible for the suppression of star formation in the most massive of galaxies. Commonly active galactic nuclei (AGN) are invoked to fulfil this role, but the exact means by which they do so is still the topic of much debate, with studies finding evidence for both the suppression and enhancement of star formation in AGN hosts. Using the ZFOURGE (FourStar Galaxy Evolution) and NMBS (Newfirm Medium Band Survey) galaxy surveys, we investigate the host galaxy properties of a mass-limited (M greater than or equal to 10... M...), high-luminosity (L... > 10... W Hz...) sample of radio-loud AGN to a redshift of z = 2.25. In contrast to low-redshift studies, which associate radio-AGN activity with quiescent hosts, we find that the majority of z > 1.5 radio-AGN are hosted by star-forming galaxies. Indeed, the stellar populations of radio-AGN are found to evolve with redshift in a manner that is consistent with the non-AGN mass-similar galaxy population. Interestingly, we find that the radio-AGN fraction is constant across a redshift range of 0.25 less than or equal to z < 2.25, perhaps indicating that the radio-AGN duty cycle has little dependence on redshift or galaxy type. We do however see a strong relation between the radio-AGN fraction and stellar mass, with radio-AGN becoming rare below ~10... M... or a halo mass of 10... M... This halo-mass threshold is in good agreement with simulations that initiate radio-AGN feedback at this mass limit. Despite this, we find that radio-AGN host star formation rates are consistent with the non-AGN mass-similar galaxy sample, suggesting that while radio-AGN are in the right place to suppress star formation in massive galaxies they are not necessarily responsible for doing so. (ProQuest: ... denotes formulae/symbols omitted.)
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stv2468