Open AccessSimulating galaxy clusters – II. Global star formation histories and the galaxy populations
Author(s) -
Romeo Alessio D.,
Portinari Laura,
SommerLarsen Jesper
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09239.x
Subject(s) - physics , astrophysics , astronomy , brightest cluster galaxy , galaxy formation and evolution , elliptical galaxy , galaxy cluster , lenticular galaxy , interacting galaxy , luminosity function , galaxy , galaxy merger , luminosity
We performed N ‐body + hydrodynamical simulations of the formation and evolution of galaxy groups and clusters in a Λ cold dark matter cosmology. The simulations invoke star formation, chemical evolution with non‐instantaneous recycling, metal‐dependent radiative cooling, strong starbursts and (optionally) active galactic nucleus (AGN) driven galactic superwinds, effects of a meta‐galactic ultraviolet field and thermal conduction. The properties of the galaxy populations in two clusters, one Virgo‐like ( T ∼ 3 keV) and one (sub)Coma‐like ( T ∼ 6 keV) , are discussed. The global star formation rates of the cluster galaxies are found to decrease very significantly from redshift z = 2 to 0, in agreement with observations. The total K ‐band luminosity of the cluster galaxies correlates tightly with total cluster mass, and for models without additional AGN feedback, the zero‐point of the relation matches the observed one fairly well. Compared to the observed galaxy luminosity function (LF), the simulations nicely match the number of intermediate‐mass galaxies ( −20 ≲ M B ≲−17 , smaller galaxies being affected by resolution limits) but they show a deficiency of bright galaxies in favour of an overgrown central dominant (cD) galaxy. High‐resolution tests indicate that this deficiency is not simply due to numerical ‘overmerging’. The redshift evolution of the LFs from z = 1 to 0 is mainly driven by luminosity evolution, but also by merging of bright galaxies with the cD. The colour–magnitude relation of the cluster galaxies matches the observed ‘red sequence’, although with a large scatter, and on average galaxy metallicity increases with luminosity. As the brighter galaxies are essentially coeval, the colour–magnitude relation results from metallicity rather than age effects, as observed. On the whole, a top‐heavy initial mass function appears to be preferably required to reproduce also the observed colours and metallicities of the stellar populations.