Making Intracluster Light - The Role of Groups

• Tidal stripping of stars from galaxies orbiting in clusters...(eg, Merritt 1982, 1984; Richstone & Malumuth 1983; Malumuth & Richstone 1984; Calcaneo-Roldan etal 2000)
  

• ...exacerbated by high speed collisions of galaxies. (Moore et al 1996, 1998)

But clusters accrete hierarchically: galaxies are added in groups, not one by one.
The Mice, living in the outskirts of the Coma cluster. (courtesy John Hibbard) So how does the interplay between local (group-scale) interactions and the cluster field impact tidal stripping?	Merger of cluster-accreted pair (Mihos in prep)

Collisionless simulation of the formation of ICL (Mihos et al 2006; Rudick et al 2006; expanding on techniques of Dubinski 1998) Identify z=0 galaxy cluster (log M ~ 14) in cosmological simulation. Track particles back to z=2. Excise galaxy-scale halos, replace w/ hi-res E/S galaxy models (> 10% MMW). Galaxy insertion follows HOD scheme (eg, Berlind & Weinberg). Galaxy type set by local galaxy density. ~ 120 galaxies, resolution in stars ~ 300 pc. Resimulate to z=0. Make quantitative maps of ICL (Rudick et al 2006).

• Much ICL spawned in group environment, then completely liberated as groups fall together to form clusters.
• Morphology and luminosity tied to dynamical evolution
• Amount of ICL grows as cluster evolves and accretes
  
• Morphology: Initially significant substructure (streams, plumes); later a smooth, diffuse ICL as the tidally stripped ICL "mixes" in the cluster environment.