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the centre. This further suggests that it takes a significant amount of time after the infall of a galaxy into a cluster until stars are efficiently stripped from it. Keeping this in mind, it is not at all surprising that Murante et al. (2007) find that most of the stripping happens at z < 1. 

We also checked the stellar masses of the galaxies in which the different components (satellite galaxy, BCG, and ICL stars) resided when they fell into the forming cluster. This is illustrated in Fig. 13. The lower panel shows the dis- tribution of all infalling stars according to the stellar mass of the galaxy in which they fell into the cluster. The upper panel shows for each stellar mass bin of the infalling galaxy the fraction of stars that at z = 0 reside in the cluster’s satel- lite galaxies, the BCG, and the ICL. Again, the results were averaged over four clusters to reduce noise in the curves. − 

For stellar masses below ∼ 4 × 10 $^{9}$h $^{1}$M ⊙ , the fraction of stars that get stripped from an infalling galaxy and become intracluster stars strongly increases in our simulations. This is because these objects are poorly resolved, as also shown by our analysis of the convergence of the properties of the satellite galaxy population in Sect. 2.3. However, looking at the lower panel we see that only very few stars fall into the cluster in such small, poorly resolved galaxies. Their disrup- tion does therefore not significantly bias our predictions for the ICL. On the other hand, for more massive and well re- solved galaxies, we find that the fraction of stars that gets 

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liberated and joins the ICL increases with the galaxy’s stel- lar mass. The most massive galaxies are also most likely to merge with the BCG, as can be seen by the strong increase of the BCG fraction. Accordingly, the fraction of stars that remains bound to an infalling galaxy decreases with stellar mass. This can be understood due to the shorter dynami- cal friction timescale for massive galaxies, while at the same time their tidal radius is larger. 

Furthermore, we investigated what fraction of intraclus- ter stars comes from completely dissolved galaxies. We did this by constructing a merger tree. For each SUBFIND (sub- )halo found in one snapshot we searched for the descendant (sub-)halo in the next snapshot that contains the largest number of the object’s original star particles. In case this would yield the cluster’s main halo as descendant, we also check which subhalo of the cluster contains the largest num- ber of the satellite galaxy’s stars. If this subhalo still con- tains more than 10% of the original galaxy’s star particles we consider it as the descendant, and not the cluster’s main halo. This allows us to follow satellite galaxies even when they are strongly tidally stripped between two subsequent simulation snapshots. 

We find that the fraction of intracluster stars that comes from dissolved galaxies, i.e. galaxies that either merged with the BCG or were completely tidally disrupted, depends on halo mass. While we have performed this analysis only for four clusters, we find a systematic trend where this fraction drops from 75% for a 5 × 10 $^{13}$h − $^{1}$M ⊙ group to 22% for a 3 × 10 $^{14}$h − $^{1}$M ⊙ cluster. 

As discussed above, the mean fraction of stars that gets stripped from an infalling galaxy and becomes part of the ICL depends on the mass of the galaxy. On the other hand, this also means that the fraction of intracluster stars may be biased in simulations that do not reproduce the correct galaxy stellar mass function. Getting the latter right in cos- mological hydrodynamical simulations is, however, a long- standing problem which has not yet been solved satisfac- 

