The Formation of Intracluster Light

CWRU collaborators: John Feldmeier, Heather Morrison, Paul Harding
CWRU students: Cameron McBride (Pittsburgh), Nathan Kaib (Washington), Steve Rodney (Hawaii)

When did it form? How did it form?
  • Early cluster collapse or late accretion?
  • Low luminosity galaxies or high?
  • Coherent substructure or diffuse ICL?
  • Metallicity and kinematic properties?
  • Correlations with cluster properties?

Theoretical work has largely focused on tidal stripping of individual galaxies in a fixed potential well (eg Merritt 1983; Richstone & Malamuth 1983; Moore etal 1996; Calcaneo-Roldan etal 2000) and ignored two important effects: preprocessing in groups, and heating by substructure (Gnedin 2003).

Full cosmologically-motivated simulations are needed to study the phenomenon (eg Dubinski etal 2000; Napolitano etal 2003; Mihos etal 2003).



Numerical Simulations:

We use a similar technique to Dubinski (2000):
  • LCDM cosmological simulation
  • ID clusters and subhalos at high redshift (z=3)
  • substitute individual galaxy models (to 0.1 L*)
  • evolve (collisionlessly) to z=0


We see significant kinematic and spatial substructure at early times; at late times much has been mixed/heated away. However, significant substructure remains even at z=0 at low surface brightnesses.
(Mihos etal 2003)


Simulations also suggest a link between a cluster's dynamical state and its ICL properties. Is this observed?

Observational studies of ICL (Feldmeier etal (2002, 2003), Feldmeier etal IAU poster):
  • Deep imaging of Abell clusters of differing Bautz-Morgan types to search for ICL
  • KPNO 2.1m (soon: CWRU Burrell Schmidt for nearby clusters)
  • Limiting surface brightness: muV = 26-27 (S/N = 5), 28-29 (S/N = 1)


Abell 1413 (BM Type I: cD)
Raw Image
 Smooth Isophote subtracted image



Abell 1413 shows slight excess over r1/4 law.


Abell 1914 (BM Type II: several luminous galaxies)





Speculation/Comments:
  • ICL morphology seems linked to cluster type
  • Weak correlation beween ICL amount and cluster type
  • Only seeing tip of the iceberg!
  • PNe will be a powerful tool (deep equivalent surface brightness, plus kinematics)
(compilation from Ciardullo etal IAU poster)