The Occurrence of Compact Groups of Galaxies Through Cosmic Time
| Autor: | Wiens, Christopher D., Wenger, Trey V., Tzanavaris, Panayiotis, Johnson, Kelsey E., Gallagher, S. C., Xiao, Liting |
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| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | ApJ (2019) 873 124 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.3847/1538-4357/ab053e |
| Popis: | We use the outputs of a semi-analytical model of galaxy formation run on the Millennium Simulation to investigate the prevalence of 3D compact groups (CGs) of galaxies from $z = 11$ to 0. Our publicly available code identifies CGs using the 3D galaxy number density, the mass ratio of secondary+tertiary to the primary member, mass density in a surrounding shell, the relative velocities of candidate CG members, and a minimum CG membership of three. We adopt "default" values for the first three criteria, representing the observed population of Hickson CGs at $z = 0$. The percentage of non-dwarf galaxies ($M > 5 \times 10^{8}h^{-1}\ M_{\odot}$) in CGs peaks near $z \sim 2$ for the default set, and between $z \sim 1 - 3$ for other parameter sets. This percentage declines rapidly at higher redshifts ($z \gtrsim 4$), consistent with the galaxy population as a whole being dominated by low-mass galaxies excluded from this analysis. According to the most liberal criteria, $\lesssim 3\%$ of non-dwarf galaxies are members of CGs at the redshift where the CG population peaks. Our default criteria result in a population of CGs at $z < 0.03$ with number densities and sizes consistent with Hickson CGs. Tracking identified CG galaxies and merger products to $z = 0$, we find that $\lesssim 16\%$ of non-dwarf galaxies have been CG members at some point in their history. Intriguingly, the great majority ($96\%$) of $z = 2$ CGs have merged to a single galaxy by $z= 0$. There is a discrepancy in the velocity dispersions of Millennium Simulation CGs compared to those in observed CGs, which remains unresolved. Comment: Revised version to match published version. Uses likeapj.cls (v1.1.5), likeapj.bst style files, 11 pages, 7 figures, 1 table. Compact group detection code available at https://github.com/cdw9bf/CompactGroup ; LaTex style files available at https://github.com/qtast/likeapj/releases/latest ; Data acquisition code available at https://github.com/tvwenger/millennium-tap-query |
| Databáze: | arXiv |
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