Аннотация
In order to understand the processes that quench star formation within rich
clusters, we construct a library of subhalo orbits drawn from lambdaCDM
cosmological N-body simulations of four rich clusters. The orbits are combined
with models of star formation followed by quenching in the cluster environment
to predict colours and spectroscopic line indices of satellite galaxies. Simple
models with only halo mass-dependent quenching and without environmental (i.e.
cluster-dependent) quenching fail to reproduce the observed cluster-centric
colour and absorption linestrength gradients. Models in which star formation is
instantly quenched at the virial radius also fail to match the observations.
Better matches to the data are achieved by more complicated bulge-disc models
in which the bulge stellar populations depend only on the galaxy subhalo mass
while the disc quenching depends on the cluster environment. In the most
successful models quenching begins at pericentre, operating on an exponential
timescale of 2 -- 3 Gyr, with the shorter timescale being a better match to
disc colours as a function of cluster-centric radius and the longer being a
better fit to the radial dependence of stellar absorption line indices. The
models thus imply that the environments of rich clusters must impact star
formation rates of infalling galaxies on relatively long timescales - several
times longer than a typical halo spends within the virial radius of a cluster.
This scenario favours gentler quenching mechanisms such as slow "strangulation"
over more rapid ram-pressure stripping.
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