Evolution of compact and fossil groups of galaxies from semi-analytical models of galaxy formation

Abstract

We compare the mean mass assembly histories of compact and fossil galaxy groups in the Millennium dark matter simulation and an associated semi-analytic galaxy formation model. Tracing the halo mass of compact groups (CGs) from z=0 to z=1 shows that, on average, 55 per cent of the halo mass in compact groups is assembled since z~1, compared to 40 per cent of the halo mass in fossil groups (FGs) in the same time interval, indicating that compared to FGs, CGs are relatively younger galaxy systems. At z=0, for a given halo mass, fossil groups tend to have a larger concentration than compact groups. Investigating the evolution of CG's parameters show that they become more compact with time. CGs at z=0.5 see their magnitude gaps increase exponentially, but it takes ~10 Gyr for them to reach a magnitude gap of 2 magnitudes. The slow growth of the magnitude gap leads to only a minority (~41 per cent) of CGs selected at z=0.5 turning into a FG by z=0. Also, while three-quarters of FGs go through a compact phase, most fail to meet the CG isolation criterion, leaving only ~30 per cent of FGs fully satisfying the CG selection criteria. Therefore, there is no strong link of CGs turning into FGs or FGs originating from CGs. The relation between CGs and FGs is thus more complex, and in most cases, FGs and CGs follow different evolutionary tracks.

11 pages, 11 figures, Accepted for publication in ApJ

References in corpus (11)

• The hierarchical formation of the brightest cluster galaxies
• The X-Ray Concentration-Virial Mass Relation
• The Mass Assembly of Fossil Groups of Galaxies in the Millennium Simulation
• The Fossil Phase in the Life of a Galaxy Group
• Compact groups in theory and practice - III. Compact groups of galaxies in the Sixth Data Release of the Sloan Digital Sky Survey
• Compact Groups of Galaxies selected by stellar mass: The 2MASS Compact Group Catalogue
• Mining the gap: evolution of the magnitude gap in X-ray galaxy groups from the 3 square degree XMM coverage of CFHTLS
• Compact groups in theory and practice - I. The spatial properties of compact groups
• Intragroup and Galaxy-Linked Diffuse X-ray Emission in Hickson Compact Groups
• Properties of Hickson Compact Groups and of the Loose Groups within which they are Embedded
• The nature of the nearest compact group of galaxies from precise distance measurements

Cited by in corpus (15)

• Compact Groups of Galaxies in Sloan Digital Sky Survey and LAMOST Spectral Survey: I. The Catalogs
• A finer view of the conditional galaxy luminosity function and magnitude-gap statistics
• Fossil group origins IX. Probing the formation of fossil galaxy groups with stellar population gradients of their central galaxies
• Merger history of central galaxies in Semi-Analytic Models of galaxy formation
• Compact groups from semi-analytical models of galaxy formation -- II: Different assembly channels
• The SAMI Galaxy Survey: Kinematics of stars and gas in brightest group galaxies; the role of group dynamics
• Abundance and group coalescence timescales of compact groups of galaxies in the EAGLE simulation
• Using Strong Gravitational Lensing to Identify Fossil Group Progenitors
• On the reliability of photometric and spectroscopic tracers of halo relaxation
• The Occurrence of Compact Groups of Galaxies Through Cosmic Time
• Fossil group origins X. Velocity segregation in fossil systems
• The Compactness of Galaxy Groups in the Sloan Digital Sky Survey
• Cosmic Pathways for Compact Groups in the Milli-Millennium Simulation
• Compact Groups in GDM Cosmological Simulations
• Evolution of Galaxy Types and HI Gas in Hickson Compact Groups