Galaxy And Mass Assembly (GAMA): The absence of stellar mass segregation in galaxy groups and consistent predictions from GALFORM and EAGLE simulations

Kafle, PR, Robotham, ASG, Lagos, CDP, Davies, LJ, Moffett, AJ, Driver, SP, Andrews, SK, Baldry, IK, Bland-Hawthorn, J, Brough, S, Cortese, L, Drinkwater, MJ, Finnegan, R, Hopkins, AM and Loveday, J (2016) Galaxy And Mass Assembly (GAMA): The absence of stellar mass segregation in galaxy groups and consistent predictions from GALFORM and EAGLE simulations. Monthly Notices of the Royal Astronomical Society, 463 (4). pp. 4194-4209. ISSN 0035-8711

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Abstract

We investigate the contentious issue of the presence, or lack thereof, of satellites mass segregation in galaxy groups using the Galaxy And Mass Assembly (GAMA) survey, the GALFORM semi-analytic and the EAGLE cosmological hydrodynamical simulation catalogues of galaxy groups. We select groups with halo mass $12 \leqslant \log(M_{\text{halo}}/h^{-1}M_\odot) <14.5$ and redshift $z \leqslant 0.32$ and probe the radial distribution of stellar mass out to twice the group virial radius. All the samples are carefully constructed to be complete in stellar mass at each redshift range and efforts are made to regularise the analysis for all the data. Our study shows negligible mass segregation in galaxy group environments with absolute gradients of $\lesssim0.08$ dex and also shows a lack of any redshift evolution. Moreover, we find that our results at least for the GAMA data are robust to different halo mass and group centre estimates. Furthermore, the EAGLE data allows us to probe much fainter luminosities ($r$-band magnitude of 22) as well as investigate the three-dimensional spatial distribution with intrinsic halo properties, beyond what the current observational data can offer. In both cases we find that the fainter EAGLE data show a very mild spatial mass segregation at $z \leqslant 0.22$, which is again not apparent at higher redshift. Interestingly, our results are in contrast to some earlier findings using the Sloan Digital Sky Survey. We investigate the source of the disagreement and suggest that subtle differences between the group finding algorithms could be the root cause.

Item Type: Article 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 P. R. Kafle, A. S. G. Robotham, C. del P. Lagos, L. J. Davies, A. J. Moffett, S. P. Driver, S. K. Andrews, I. K. Baldry, J. Bland-Hawthorn, S. Brough, L. Cortese, M. J. Drinkwater, R. Finnegan, A. M. Hopkins, J. Loveday; Galaxy And Mass Assembly (GAMA): the absence of stellar mass segregation in galaxy groups and consistent predictions from GALFORM and EAGLE simulations. Mon Not R Astron Soc 2016; 463 (4): 4194-4209. doi: 10.1093/mnras/stw2290 is available online at: http://dx.doi.org/10.1093/mnras/stw2290 astro-ph.GA; astro-ph.GA; astro-ph.CO Q Science > QB AstronomyQ Science > QC Physics Astrophysics Research Institute Oxford University Press Author 16 Sep 2016 09:04 23 Sep 2018 08:10 10.1093/mnras/stw2290 http://researchonline.ljmu.ac.uk/id/eprint/4161