THE EVOLUTION OF CENTRAL GROUP GALAXIES IN HYDRODYNAMICAL SIMULATIONS

Journal Article · Wed Jan 20 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/709/1/218· OSTI ID:21392343

Feldmann, R; Carollo, C M ^[1]; Mayer, L; Lake, G ^[2]; Renzini, A ^[3]; Quinn, T; Stinson, G S ^[4]; Yepes, G ^[5]

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1. Institute for Astronomy, ETH Zuerich, Wolfgang-Pauli-Strasse 16, 8093 Zuerich (Switzerland)
2. Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zuerich (Switzerland)
3. INAF Osservatorio Astronomico di Padova, Vicolo Dell'Osservatorio, 5, 35122 Padova (Italy)
4. Astronomy Department, University of Washington, Seattle, WA 98195-1580 (United States)
5. Grupo de Astrofisica, Universidad Autonoma de Madrid, 28049 Madrid (Spain)

We trace the evolution of central galaxies in three approx10{sup 13} M{sub sun} galaxy groups simulated at high resolution in cosmological hydrodynamical simulations. In all three cases, the evolution in the group potential leads, at z = 0, to central galaxies that are massive, gas-poor early-type systems supported by stellar velocity dispersion and which resemble either elliptical or S0 galaxies. Their z approx 2-2.5 main progenitors are massive (M{sub *} approx (3-10) x 10{sup 10} M{sub sun}), star-forming (20-60 M{sub sun} yr{sup -1}) galaxies which host substantial reservoirs of cold gas (approx5 x 10{sup 9} M{sub sun}) in extended gas disks. Our simulations thus show that star-forming galaxies observed at z approx 2 are likely the main progenitors of central galaxies in galaxy groups at z = 0. At z approx 2 the stellar component of all galaxies is compact, with a half-mass radius <1 kpc. The central stellar density stays approximatively constant from such early epochs down to z = 0. Instead, the galaxies grow inside out, by acquiring a stellar envelope outside the innermost approx2 kpc. Consequently the density within the effective radius decreases by up to 2 orders of magnitude. Both major and minor mergers contribute to most (70{sup +20}{sub -15}%) of the mass accreted outside the effective radius and thus drive an episodical evolution of the half-mass radii, particularly below z = 1. In situ star formation and secular evolution processes contribute to 14{sup +18}{sub -9}% and 16{sup +6}{sub -11}%, respectively. Overall, the simulated galaxies grow by a factor approx4-5 in mass and size since redshift z approx 2. The short cooling time in the center of groups can foster a 'hot accretion' mode. In one of the three simulated groups this leads to a dramatic rejuvenation of the central group galaxy at z < 1, affecting its morphology, kinematics, and colors. This episode is eventually terminated by a group-group merger. Mergers also appear to be responsible for the suppression of cooling flows in the other two groups. Passive stellar evolution and minor galaxy mergers gradually restore the early-type character of the central galaxy in the cooling flow group on a timescale of approx1-2 Gyr. Although the average properties of central galaxies may be set by their halo masses, our simulations demonstrate that the interplay between halo mass assembly, galaxy merging, and gas accretion has a substantial influence on the star formation histories and z = 0 morphologies of central galaxies in galaxy groups.

• OSTI ID: 21392343
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 709; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COOLING TIME
EVOLUTION
GALAXIES
MORPHOLOGY
RED SHIFT
SIMULATION
STAR EVOLUTION
STARS