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Occurrence of Compact Groups of Galaxies through Cosmic Time

Wiens, Christopher D. and Wenger, Trey V. and Tzanavaris, Panayiotis and Johnson, Kelsey E. and Gallagher, S. C. and Xiao, Liting (2019) Occurrence of Compact Groups of Galaxies through Cosmic Time. Astrophysical Journal, 873 (2). Art. No. 124. ISSN 1538-4357.

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We use the outputs of a semianalytical 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 nondwarf galaxies (M > 5 × 10^8 h^(−1) M ⊙) in CGs peaks near z ~ 2 for the default set and in the range of z ~ 1–3 for other parameter sets. This percentage declines rapidly at higher redshifts (z ≳ 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, ≾3% of nondwarf 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 ≾16% of nondwarf 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Wenger, Trey V.0000-0003-0640-7787
Tzanavaris, Panayiotis0000-0001-5737-5055
Johnson, Kelsey E.0000-0001-8348-2671
Xiao, Liting0000-0003-2703-449X
Additional Information:© 2019 The American Astronomical Society. Received 2017 April 26; revised 2019 January 23; accepted 2019 January 25; published 2019 March 12. We thank the referee, G. Mamon, for detailed input that improved the presentation in this paper. C.D.W. thanks the University of Virginia Small Research Grants for undergraduates for their support of this project. T.V.W is supported by the NSF through the Grote Reber Fellowship Program administered by Associated Universities, Inc./National Radio Astronomy Observatory, the D.N. Batten Foundation Fellowship from the Jefferson Scholars Foundation, the Mars Foundation Fellowship from the Achievement Rewards for College Scientists Foundation, and the Virginia Space Grant Consortium. K.E.J. is grateful to the David and Lucile Packard Foundation for their generous support. S.C.G. thanks the Natural Science and Engineering Research Council of Canada and the Ontario Early Researcher Award Program for support. P.T. acknowledges support by NASA ADAP 14-ADAP14-0200 (PI Tzanavaris).
Funding AgencyGrant Number
University of VirginiaUNSPECIFIED
Associated Universities, Inc.UNSPECIFIED
National Radio Astronomy ObservatoryUNSPECIFIED
Jefferson Scholars FoundationUNSPECIFIED
Virginia Space Grant ConsortiumUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Natural Science and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Ontario Early Researcher AwardUNSPECIFIED
Subject Keywords:galaxies: evolution – galaxies: groups: general – galaxies: interactions – galaxies: statistics
Issue or Number:2
Record Number:CaltechAUTHORS:20190313-092913460
Persistent URL:
Official Citation:Christopher D. Wiens et al 2019 ApJ 873 124
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:93762
Deposited By: Tony Diaz
Deposited On:13 Mar 2019 17:03
Last Modified:03 Oct 2019 20:57

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